Dissertations / Theses on the topic 'Fermented food'

Akamu is a lactic acid bacteria fermented cereal-based food that complements infant diets in most African countries. Uncontrolled fermentation increases the variability in quality and safety of akamu. This study was aimed at the controlled fermentation of akamu with selected lactic acid bacteria (LAB), investigation of the probiotic potential of the LAB and the effect of variation in production method on the product quality and sensory properties. PCR-DGGE analysis of traditional akamu samples revealed LAB community dominated by Lactobacillus fermentum, L. plantarum, L. delbrueckii subsp. bulgaricus and L. helveticus. Isolated yeasts were Candida tropicalis, C. albicans, Clavispora lusitaniae and Saccharomyces paradoxus. The isolated Lactobacillus plantarum strains (NGL5 and NGL7) fermented irradiated ground maize slurries and produced significant levels of lactic acid (>73 mmol L-1) and low pH ≤3.63 displaying inhibitory activity against Salmonella enterica serovar Enteritidis NCTC 5188, Escherichia coli 1077 (NCTC 11560), Bacillus cereus NCIMB 11925, Staphylococcus aureus NCTC 3750 and Listeria monocytogenes NCTC 7973 in MRS agar and E. coli 1077 in maize slurry fermentation. Viability of both strains of L. plantarum at pH 2 after 3 h was reduced from ≥8.26±0.05 to ≤4.94±0.49 Log10 CFU mL-1 while incubation in 0.3% bile allowed growth to 5.73±0.13 and 7.93±0.12 Log10 CFU mL-1 after 6 h for NGL5 and NGL7 respectively. Auto-aggregation of the L. plantarum strains at 37oC (≥25 after 5 h) correlated with adhesion to hydrocarbons (<15, 26, 33 and 64% for Hexane, Hexadecane, Ethyl acetate and Chloroform respectively). The strains failed to exhibit gelatinase or haemolytic activity but adhered to porcine mucin (OD403 nm ≥0.63 with viability ≥6.52 Log10 CFU mL-1) and Caco-2 cells (≥5.13 Log10 CFU mL-1). The ash, mineral (Ca, K, Mg, Na, S and Zn), IDF, SDFP and TDF content of the L. plantarum fermented ground maize slurries were significantly (p≤0.05) higher than that of the traditional akamu but the peak and final viscosities (139.5 and 68.5 cP respectively) were significantly (p≤0.05) the least. The aroma, appearance, colour, flavour and texture of the resultant porridges were liked moderately by 75% of the assessors. This study demonstrated that fermentation with the L. plantarum strains would contribute towards product safety and the L. plantarum strains possessed some probiotic potential that could be beneficial to the consumers particularly in those developing countries were the main staple foods are fermented cereals.

Dissertation 'consists of a selection of 71 publications produced over the period 1975-2001, which were drawn from the more complete list of 198 original research papers, review articles and books published over the same period' -- declaration.
Thesis (PhD Food Sc )--Stellenbosch University, 2001.
ENGLISH ABSTRACT: One of the curious facts about the food industry is that many of the processes in use today were being practised, in some form or other, by the Roman legions as they marched across Europe and beyond. Certainly they were familiar with the basic techniques of fermentation, and much current research into fermented foods is concerned with understanding the fundamental nature of these traditional processes, and how the individual stages in a particular fermentation can be better controlled. Recent developments in the dairy industry have tended to reflect this pattern and, over the years, my research group has done much to support the expanding markets for yoghurt and similar fermented milks. Our evaluation of the polysaccharide-producing characteristics of starter cultures, for example, encouraged yoghurt manufacturers to match physical properties to the perceived demands of consumers, and most culture suppliers followed this lead by labelling their products with precise designations as to their potential for imparting viscosity to a retail item. Similarly, my group was the first to record the unique physical properties of the concentrated yoghurt, labneh, C 230 g 1-1 total solids) that had been made for hundreds of years by draining whey from natural yoghurt hanging in a cloth or animal-skin bag. This detailed analysis of the product facilitated the application of ultra-filtration to natural yoghurt to generate a product with a quality that matched traditionallabneh and, today, factories in the Middle East, Greece and elsewhere are using modern membrane-filtration plants to satisfy a growing market demand. Our success in publicising the attractive properties of concentrated yoghurt encouraged me to devote time to yet another 'historical' concept, namely the apparent 'health benefits' derived by small communities in Eastern Europe from consuming kefir and koumiss. In the West, the flavour and texture of these latter products have never been accepted, but employing similar cultures to produce 'health-promoting' bio-yoghurts opened an entirely new avenue for research. As clinical evidence in support of the prophylactic and therapeutic properties of Lactobacillus acidophilus and a species of Bifidobacterium became available, so it became apparent that the therapeutic advantage that accompanies the regular ingestion of 'bio-yoghurts' depended on the survival of these microfloras over the stipulated shelf-lives of the retail vehicles. However, no laboratory medium was immediately available for the simultaneous enumeration of Lb. acidophilus and Bifidobacterium along with the yoghurt cultures, i.e. Streptococcus thermophilus and Lactobacillus delbrueckii sub-sp. bulgaricus. Designing such a medium became a priority for one of my students, and, even today, the procedures that he derived are being used by consumer groups that monitor the performance of the major dairy companies in England. If the improved quality of yoghurts and 'bio-yoghurts' had a major impact on consumer perceptions of fermented milks, the food sector in England gradually became aware of an even more dramatic change in consumer attitudes. Thus twenty years ago, cheese meant 'Cheddar' but, following a 'deluge' of television publicity about the attractions of 'exotic' catering, housewives began demanding mozzarella and mascarpone for lavish desserts, Feta to sprinkle over salads and Halloumi to grill or fry. In turn, exporting countries like Italy, Greece and Cyprus came under intense pressure to increase supplies of top quality products. Local manufacturers soon realised, however, that there was little information available concerning the scientific basis to the procedures employed to make some of these traditional cheeses, and my research group was selected by Funding Agencies in Greece and Cyprus to act as a focus for a series of studies of Feta and Halloumi cheese. The need to eliminate pathogens from the storage brines of Feta cheese without killing the yeasts and bacteria associated with maturation became an important consideration for exporters, and one of my students exploited a novel procedure employing furocoumarins and long-wave ultra-violet light to achieve the desired selective inactivation. At present, the economics of commercial application are somewhat dubious but, as soon as cheap, synthetic, non-toxic furocoumarins become more readily available, the system may well merit re-evaluation. We did confirm, however, that the metabolic activities of the yeasts and bacteria typically isolated from storage brines are essential for flavour development in Feta cheese, and that similar microfloras are instrumental in the development of the important charactistics of traditional Halloumi cheese. In particular, a new species of lactic acid bacterium, Lactobacillus cypricasei, was isolated from samples of the traditional ovine cheese, but whether or not the species has a unique role(s) in the maturation process remains an open question. Clearly there is still much to learn but, if the activities of my reseach group have added just a little to the scientific background essential for future studies of cheese and fermented milks, then their completion will have been worthwhile.
AFRIKAANSE OPSOMMING: Een van die merkwaardigste feite omtrent die voedselindustrie is dat baie van die prosesse wat vandag gebruik word, in een of ander vorm deur die Romeinse magte gebruik is toe hulle deur Europa marsjeer het. Basiese fermentasie tegnieke was aan hulle bekend, en heelwat huidige navorsing oor gefermenteerde voedsel is gemik daarop om die fundamentele natuur van hierdie tradisionele prosesse te verstaan en hoe die individuele stappe in 'n spesifieke fermentasie beter beheer kan word. Onlangse ontwikkelinge in die suiwelindustrie reflekteer hierdie patroon, en my navorsingsgroep het oor die jare heelwat gedoen om die groeiende markte vir joghurt en soortgelyke gefermenteerde melk te ondersteun. Ons evaluasie van die polisakkariedproduserende eienskappe van suursels het byvoorbeeld joghurtvervaardigers gehelp om fisieke eienskappe daar te stel wat verbruikers tevrede sal stel. Meeste verskaffers van kulture het hierdie voorbeeld gevolg deur hul produkte so te etiketteer dat duidelik gewys word watter potensiaal dit het om viskositeit aan die finale produk te verleen. Verder was my groep die eerste om die unieke fisiese eienskappe van die gekonsentreerde joghurt, labneh (230 g 1-1 totale vastestowwe) te bepaal, wat vir honderde jare gemaak is deur die wei van natuurlike joghurt te dreineer deur dit in "n materiaal- of diervelsak te hang. "n Gedetailleerde analise van hierdie tradisionele produk het bygedra tot die gebruik van ultrafiltrasie op natuurlike joghurt om "n produk te gee met dieselfde kwaliteit as tradisionele labneh. Vandag gebruik fabrieke in die Midde Ooste, Griekeland en elders moderne membraan-filtrasie aanlegte om in die groeiende vraag na die produk te voorsien. Ons sukses met die bekendmaking van die aantreklike eienskappe van gekonsentreerde joghurt het my aangespoor om tyd te spandeer aan nog 'n sogenaamde "historiese" konsep, naamlik die skynbare gesondheidsvoordele van klein gemeenskappe in Oos-Europa wat kefir en koumiss verbruik. In die Weste is die smaak en tekstuur van hierdie produkte nooit werklik aanvaar nie, maar om soortgelyke kulture te gebruik om "gesondheidsbevorderende" bio-joghurt te produseer, het 'n hele nuwe navorsingsveld daargestel. Soos kliniese bewyse van die terapeutiese en voorkomende voordele van Lactobacillus acidophilus en 'n spesie van Bifidobacterium bekend gemaak is, het dit duidelik geword dat die terapeutiese voordele wat saamgaan met die gereelde inname van "bio-joghurts", afhang van die oorlewing van hierdie mikroflora oor die gestipuleerde rakleeftyd van die kommersiële produkte. Geen laboratorium medium was egter onmiddellik beskikbaar vir die gelyktydige telling van Lb. actdophilus en Bifldobacterium tesame met die joghurt kulture Streptococcus thermophilus en Lb. delbrueckii sub-sp. bulgaricus. Die ontwikkeling van so 'n medium het een van my studente se prioriteit geword, en selfs vandag word die prosedures wat deur hom ontwikkel is, gebruik deur verbruikersgroepe wat die optrede van groot suiwelmaatskappye in Engeland monitor. lndien die verbeterde kwaliteit van joghurts en bio-joghurts 'n groot impak gehad het op verbruikers se persepsie van gefermenteerde melk oor Wes-Europa heen, het die voedselsektor in Engeland bewus geraak van selfs 'n meer dramatiese verandering in verbruikers se houding. Twintig jaar terug het kaas "Cheddar" beteken, maar na 'n stortvloed televisie advertensies oor die aanloklikheid van eksotiese geregte, het daar by huisvroue 'n vraag ontstaan na Mozzarella en Mascarpone vir nageregte, Feta oor slaai en Halloumi om te bak of te braai. Italië, Griekeland en Siprus wat hierdie produkte uitgevoer het, het onder kwaai druk gekom om groter hoeveelhede, top-kwaliteit produkte te lewer. Plaaslike vervaardigers het gou agtergekom dat min inligting beskikbaar was oor die wetenskaplike basis van die prosedures wat gebruik word om hierdie tradisionele kase te maak en my navorsingsgroep is deur befondsingsagentskappe in Griekeland en Siprus genader om studies te doen oor sekere aspekte van die vervaardiging van Feta en Halloumi kaas. Dit het vir beide in- en uitvoerders belangrik geword om die patogene te elimineer uit die soutoplossing waarin Fetakaas gestoor word, sonder om die giste en bakterieë wat rypwording aanhelp, te dood. Een van my studente het 'n innoverende prosedure ontwikkel wat furocoumarins en lang-golf-ultra-violet lig gebruik om selektiewe inaktivering te kry. Op die oomblik is daar effense onsekerheid oor die ekonomiese implikasies van die kommersiële toepassing, maar sodra goedkoop, sintetiese, nie-toksiese furocoumarins geredelik beskikbaar word, moet die sisteem weer geëvalueer word. Ons het egter bevestig dat die metaboliese aktiwiteite van die giste en bakterieë in die stooroplossing noodsaaklik is vir geurontwikkeling in Feta kaas en dat soortgelyke mikrofloras instrumenteel is in die ontwikkeling van die belangrike karaktereienskappe van tradisionele Halloumi kaas. 'n Unieke melksuurbakterium, Lactobacillus cypricasei, is uit monsters tradisionele skaap Halloumi geïsoleer, maar of hierdie spesie 'n unieke rol speel in die verouderingsproses is nog 'n ope vraag. Duidelik is daar nog baie om te leer, maar indien my navorsingsgroep se aktiwiteite slegs 'n klein bydrae gemaak het tot die wetenskaplike agtergrond wat essensieel is vir toekomstige navorsing, was die voltooiing daarvan die moeite werd.

The study presented here was to investigate the traditional production of the Ugandan fermented cereal beverage, Obushera. The effects of germination and malting of sorghum grains under different steeping treatment were first investigated. The traditional preparation of Obushera beverage was carried out and course of fermentation monitored. The viscosity of Obushera was very low throughout the fermentation process. The microflora responsible for the fermentation of Obushera were identified. After considerable research and conduction of tests were carried out, it was found that there was no detectable quantity of alcohol in Obushera. It was also confirmed that that there were no strains of alcohol producing yeasts, such as Saccharomyces sp. found in the Obushera.

The study presented here was to investigate the traditional production of the Ugandan fermented cereal beverage, Obushera. The effects of germination and malting of sorghum grains under different steeping treatment were first investigated. The traditional preparation of Obushera beverage was carried out and course of fermentation monitored. The viscosity of Obushera was very low throughout the fermentation process. The microflora responsible for the fermentation of Obushera were identified. After considerable research and conduction of tests were carried out, it was found that there was no detectable quantity of alcohol in Obushera. It was also confirmed that that there were no strains of alcohol producing yeasts, such as Saccharomyces sp. found in the Obushera.
Master of Science (Hons) (Food Science)

Negli ultimi anni le molecole bioattive con attività antimicrobica come tossine killer, batteriocine e agenti antifungini sono state impiegate per ridurre o inibire la crescita e lo sviluppo di funghi, lieviti e batteri indesiderati in alternativa o in combinazione con i composti sintetici antimicrobici negli alimenti e nelle bevande fermentate. La presente ricerca riguarda il ruolo e la caratterizzazione di molecole bioattive prodotte da lieviti appartenenti alle specie Metschnikowia pulcherrima, Tetrapisispora phaffii, Kluyveromyces wickerhamii, Wickerhamomyces anomalus. Dopo la caratterizzazione dei composti bioattivi prodotti da questi lieviti e lo studio dell'interazione tra le molecole antimicrobiche naturali e i lieviti/ le muffe sensibili, abbiamo voluto valutare il loro possibile impiego per combattere microrganismi contaminanti nell’agricoltura biologica e nel settore vinicolo. Nella prima parte della tesi è stata valutata l’azione inibente di sette ceppi di M. pulcherrima nei confronti di lieviti enologici principalmente coinvolti nel processo di vinificazione come Pichia, Candida, Hanseniaspora, Kluyveromyces, Saccharomycodes, Torulaspora, Brettanomyces e Saccharomyces. Un’efficace azione antagonista dei ceppi di M. pulcherrima è stata osservata nei confronti di lieviti indesiderati appartenenti ai generi Pichia, Brettanomyces e Hanseniaspora, mentre tale attività antimicrobica non si evidenziava nei confronti di Saccharomyces cerevisiae. Il secondo argomento trattato ha riguardato l’isolamento del gene che codifica Kpkt, la tossina killer prodotta da Tetrapisispora phaffii che possiede un’ampia attività antimicrobica nei confronti di vari lieviti alterativi del vino. La distruzione del gene ha provocato una perdita completa del fenotipo killer confermando così che TpBgl2p esercita un'attività antimicrobica. Il risultato ottenuto è la base per valutare la possibilità di esplorare la produzione eterologa della proteina che potrebbe essere utilizzata in campo enologico per ridurre le contaminazioni nel vino in sostituzione della SO2. Nella terza parte della tesi, l’attenzione è stata focalizzata sul danno indotto dalle tossine Kwkt and Pikt, prodotte rispettivamente da Kluyveromyces wickerhamii e Wickerhamomyces anomalus, coinvolte nel biocontrollo dei lieviti spoilage Brettanomyces/ Dekkera in vinificazione. L’effetto delle micocine è stato comparato con quello dell’anidride solforosa, generalmente usata come composto sintetico antimicrobico negli alimenti e nelle bevande fermentate. I risultati hanno mostrato diversi meccanismi di controllo della crescita di B. bruxellensis tra le due tossine e tra le tossine killer e il biossido di zolfo, anche se l'attività antimicrobica di quest’ultimo è fortemente influenzata dal fattore pH. Nella quarta parte della tesi è stata valutata l'interazione tra diversi lieviti ad attività antimicrobica e alcuni funghi filamentosi che in genere colonizzano i frutti maturi. Preliminarmente è stato eseguito uno screening in piastra per valutare l’eventuale effetto inibente di 42 lieviti verso 5 muffe, che causano i principali danni in frutta e verdura durante il periodo di post-raccolta. In una seconda fase, dieci ceppi selezionati sono stati testati per la loro attività inibitoria efficace contro le muffe in test in vivo su uva, limoni, arance, fragole e ciliegie. I risultati indicano che, tra i ceppi saggiati la migliore e interessante attività antagonista nei confronti delle muffe testate, è stata mostrata da due ceppi appartenenti a Wickerhamomyces anomalus e Metschnikowia pulcherrima.
In recent years, the bioactive compounds with antimicrobial activity such as yeast killer toxins, bacteriocins and natural antifungal agents are employed to reduce or inhibit the growth and the development of undesired fungi, yeasts or bacteria. Their use was proposed in alternative or in combination to the addition of synthetic antimicrobial agent in food and fermented beverage. The present research focused on the antimicrobial role and the characterization of bioactive molecules produced by yeast strains belonging to Metschnikowia pulcherrima, Tetrapisispora phaffii, Kluyveromyces wickerhamii, Wickerhamomyces anomalus species. Following a characterization of the antimicrobial compounds produced by these yeasts and investigating on the interaction between natural antimicrobial molecules and sensitive yeasts/moulds, the present study focused the attention on their use to combat contaminating microorganisms in “organic” agriculture and in wine industry. In the first part of the present thesis seven different strains of M. pulcherrima were screened to evaluate the growth inhibition of the main oenological yeasts such as Pichia, Candida, Hanseniaspora, Kluyveromyces, Saccharomycodes, Torulaspora, Brettanomyces and Saccharomyces involved in winemaking process. The effective antagonistic actions of M. pulcherrima strains was showed on undesired wild spoilage yeasts, such as the Pichia, Brettanomyces and Hanseniaspora genera, while Saccharomyces cerevisiae was not affected by the antimicrobial action of M. pulcherrima. The objective of the second part of this study was the isolation of the gene encoding Kpkt, a killer toxin produced by Tetrapisispora phaffii. The gene disruption caused a complete loss of the killer phenotype thus confirming that TpBgl2p exerts an effective killer activity and that the gene is effectively involved in the expression of the zymocin. The result obtained gives the basis to explore the heterologous production of the protein that could be used as starter in enological field to reduce wine contamination. In the third part of the thesis, the attention was focused on the damage induced by Kwkt and Pikt killer proteins, produced by Kluyveromyces wickerhamii and Wickerhamomyces anomalus, involved in the biocontrol of Brettanomyces/ Dekkera spoilage yeast in the wine industry. The effect of mycocins was also compared with sulfur dioxide, generally used as antiseptic in food and beverage industries. The results showed different mechanisms of control of B. bruxellensis growth within the two mycocins. Different mechanisms of action were also found between killer toxins and sulfur dioxide that is strongly influenced by pH. In the fourth part of this work it was evaluated the interaction between several yeasts that exhibit antimicrobial activity and some filamentous fungi that generally colonize mature fruits. Preliminarily, a plate screening was performed to assess inhibitory effect of 42 yeasts against 5 moulds, main spoilage microorganisms in vegetables and fruits during postharvest. In a second step, ten selected strains were tested for their effective inhibitory activity against moulds in vivo assay on grapes, lemons, oranges, strawberries and cherries. Results indicated that the best antagonistic activity was exhibited by Wickerhamomyces anomalus and Metschnikowia pulcherrima species that produced a significant reduction of moulds.

La domestication est un modèle idéal pour étudier les processus évolutifs car elle implique des événements d'adaptation récents avec une sélection forte. Les champignons sont de bons organismes modèles pour étudier la domestication et plus généralement l’adaptation, grâce à leurs petits génomes et leur facilité de manipulation. Ils sont utilisés depuis longtemps pour la transformation alimentaire, par exemple P. camemberti et P. roqueforti pour la fabrication du fromage, et la levure Saccharomyces pour la fermentation du vin et de la bière. Chez ces champignons, des caractéristiques bénéfiques ont été acquises pour la transformation alimentaire, et les transferts horizontaux de gènes se sont révélés être un moyen essentiel d’adaptation rapide dans l’environnement alimentaire. Ici, j’ai étudié principalement l’adaptation de deux espèces de Penicillium relativement distantes phylogénétiquement - P. nalgiovense et P. salamii, toutes deux utilisées pour la maturation de la viande séchée. J’ai étudié si ces champignons ont été domestiqués, c’est-à-dire si les populations alimentaires se sont adaptées à l’environnement de la viande séchée, et s’il y a eu une différenciation génétique par rapport à d’autres populations; j’ai aussi recherché si des traces génomiques d’adaptation pouvaient être détectées. En analysant des génomes complets, j’ai trouvé peu de diversité génétique et de structure de population chez P. salamii et encore moins chez P. nalgiovense. Des expériences ont montré que les populations de P. salamii et P. nalgiovense provenant de viande séchée présentaient des taux de protéolyse et de lipolyse plus faibles et des couleurs différentes de celles des populations de viande non séchée. De plus, nous avons trouvé des transferts de gènes horizontaux partagés par P. salamii et P. nalgiovense et absents chez d’autres espèces de Penicillium. En résumé, ces résultats indiquent une évolution convergente et une adaptation des populations de P. salamii et P. nalgiovense à la viande séchée. J'ai également étudié les conséquences de la domestication chez le champignon utilisé pour la production de fromages bleus, P. roqueforti, montrant une faible fertilité des souches fromagères par rapport aux souches non fromagères. Les résultats de la thèse soulignent donc l'importance des transferts de gènes horizontaux pour une adaptation rapide chez les champignons et renforcent l'idée que les champignons domestiqués pour la production de nourriture sont de bons modèles pour étudier l'adaptation et l'évolution
Domestication is an ideal model to study evolutionary processes due to the recent adaptation events and strong selection it implies. Fungi in particular are good model organisms to study domestication and more generally adaptation, with their small genomes and experimental tractability. Fungi have been used for food production, e.g., P. camemberti and P. roqueforti for cheesemaking, and Saccharomyces yeast for wine and beer fermentation. In these fungi, beneficial traits have been acquired for food production, and horizontal gene transfers (HGTs) have been shown to be a major way to rapid adaptation in food environment. Here, I mainly studied the adaptation of food Penicillium fungi using two distantly related Penicillium species - P. nalgiovense and P. salamii, both used for dry-cured meat maturation, to assess whether these fungi have been domesticated, i.e., whether food populations adapted to the dry-cured meat environment, whether were genetically differentiated from other populations, and whether we could find genomic footprints of adaptive events. Using genome sequencing, we found little diversity and population structure in P. salamii and even less in P. nalgiovense. Experiments showed that both P. salamii and P. nalgiovense dry-cured meat populations had lower proteolysis and lipolysis rates and different colors from non-dry-cured meat populations. Furthermore, we found HGTs shared by P. salamii and P. nalgiovense while lacking in other Penicillium species. Altogether, these results indicate convergence evolution and adaptation in P. salamii and P. nalgiovense dry-cured meat populations, as was previously found in cheese Penicillium fungi. I also studied the consequences of domestication in the blue cheese fungus P. roqueforti, showing lower fertility of cheese strains compared to non-cheese strains. The results of the thesis thus point out the importance of HGTs for rapid adaptation in fungi and reinforce the view that fungi are ideal models to study adaptation and evolution

Thesis (M.Sc.)(Hons)--University of Western Sydney, Hawkesbury,1998.
"Thesis submitted in partial fulfillment of the requirements for the Degree of Master of Science (Honours) in Food Science." Includes bibliographical references.

Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第22499号
農博第2403号
新制||農||1077(附属図書館)
学位論文||R2||N5279(農学部図書室)
京都大学大学院農学研究科応用生物科学専攻
(主査)教授 佐藤 健司, 教授 菅原 達也, 准教授 豊原 治彦
学位規則第4条第1項該当

Os produtos lácteos probióticos e/ou simbióticos são líderes dentro do mercado de alimentos funcionais e prioridade de pesquisa em diversos países. A presença de bactérias probióticas viáveis e em alto número no produto durante sua vida de prateleira é condição essencial para assegurar o efeito probiótico. As bactérias probióticas apresentam crescimento lento no leite. O uso de co-culturas e a suplementação do leite são técnicas para superar esta dificuldade. O presente trabalho teve como objetivo verificar as condições de crescimento de Lactobacillus rhamnosus e Lactobacillus acidophilus em cultura mista com Streptococcus thermophilus em leite suplementado com hidrolisado de caseína e proteína concentrada de soro em diversas proporções (3,05 a 17,05g/L). Os parâmetros cinéticos velocidade de acidificação, tempo para atingir a velocidade máxima, tempo para atingir pH 5,0 e tempo para atingir pH 4,5 foram analisados, assim como as características físico-quimicas dos leites fermentados e a viabilidade das bactérias probióticas. A metodologia de superfície de resposta foi empregada visando otimizar a suplementação. O desempenho dos probióticos foi comparado com o leite fermentado pelas bactérias normais do iogurte nas mesmas condições. Ambos suplementos afetaram a acidificação do leite, sendo possível reduzir o tempo de fermentação. Em todos os ensaios, o nível de probióticos obtido esteve acima de 106 UFC/mL, valor mínimo de microorganismos viáveis sugerido por diversos autores para obter o efeito benéfico. Foi possível identificar modelos matemáticos preditivos.
Dairy products containing probiotics and/or symbiotics are leader in the functional foods market and, priority in research worldwide. The use of casein hydrolysate and co-cultures are useful to lower fermentation time, and, in addition, it enhances the probiotic stability. The aim of the work was to verify the growing conditions of Lactobacillus rhamnosus and Lactobacillus acidophilus in mixed cultures with Streptococcus thermophiles in milk supplemented with casein hydrolysate and whey protein with different amounts (3,05 to 17,05g/L). Response surface methodology was used to establish adequate relationship of casein hydrolysate and whey protein contents aiming their optimization. The performance of probiotic bacteria was compared with those of yogurt bacteria. The supplements influenced milk acidification. In all experiments, probiotic levels were higher than 106 cfu/mL, the minimal viable number suggested by many authors to have therapeutic benefits. Mathematical models were developed.

Thesis (MScFoodSc)--Stellenbosch University, 2001.
ENGLISH ABSTRACT: The preservation of various fresh fish products is achieved by either smoking, salting, canning, freezing or fermenting a highly perishable raw product. Since many of these facilities are not readily available, the use of fermentation as a means of preserving the product has been extensively practiced. However, the fermentation of fish is a time consuming practise and only by accelerating the process would it be possible to ensure the production of a more cost effective and readily available safe end-product. The quality of the fermented fish product is partially determined by the fermentation conditions and the metabolic activity of the microbes present. The rapid identification of the microbes present during the fermentation would enable the selection of possible starters to ensure an accelerated production of high quality fermented fish products. This study was thus undertaken to develop identification fingerprints for bacteria isolated from fermented fish products. A 1300 bp fragment of the 16S rRNA genes of each of the bacteria previously isolated was successfully amplified using the PCR technique. The isolates included strains of the genera Bacillus, Staphylococcus, Sphingomonas, Kocuria, Brevibacillus, Cryseomonas, Vibrio, Stenotrophomonas and Agrobacterium. The data obtained can, therefore, be used in the identification of these microbes isolated from other similar fermented fish products. The fingerprints could also be used to assist in determining the dominant microbial populations responsible for the characteristic qualitative changes occurring in the fish product during fermentation. The microbial composition of a fermenting fish product partially determines the quality of the end-product, therefore, the use of selected bacterial starters could result in the accelerated production of a microbial safe fermented fish product. A further objective of this study was to accelerate the production of a fermented fish product by inoculating macerated trout with either selected lactic acid bacteria (LAB) or with selected bacteria with high proteolytic activity over a 30 day fermentation period. The LAB included a combination of Lactobacillus plantarum, Lactococcus diacetylactis and Pediococcus cerevisiae strains, whereas the bacteria with high proteolytic activity included strains of Kocuria varians, Bacillus subtilis, two strains of B. amyloliquefaciens and a combination of these bacterial species. The quality of the fermented product was determined using changes in product pH, titratable acidity (%TA) and free amino nitrogen (FAN) formation as efficiency parameters. The data obtained during the fermentation of the macerated trout showed that the selected starters did not have a significant effect on the pH decrease in the product over a 30 day fermentation period. The LAB strains did not have a significant effect on the %TA of the fermenting fish product, yet the presence of these bacteria appeared to limit the FAN production in the product. The bacteria with high proteolytic activity resulted in slightly enhanced %TA values and a higher FAN content in the fermented product. It was also determined that the LAB and Kocuria varians, in contrast to the Bacillus spp. inoculums, did not survive the fermentation conditions well, possibly due to the low pH environment. The presence of the starter bacteria in the fermenting fish mixture at the end of the fermentation was also successfully determined with the use of the PCR-RFLP technique. The fermented fish product, obtained at the end of the fermentation period, had a good aroma and compared favourably to similar commercially available fermented fish products. The use of different microbial starters could in future enable the production of a diverse range of high quality products, which could be produced and marketed locally.
AFRIKAANSE OPSOMMING: Die preservering van ‘n verskeidenheid vars vis produkte word bereik deur die hoogs bederfbare produk te rook, te sout, te blik, te vries of te fermenteer. Aangesien baie van hierdie fasiliteite nie geredelik beskikbaar is nie, is die gebruik van fermentasie as ‘n preserverings metode al ekstensief beoefen. Die fermentasie van vis is egter 'n tydsame proses en slegs deur die versnelling van die proses sal dit moontlik wees om die produksie van ‘n meer koste effektiewe en geredelike beskikbare veilige eindproduk te verseker. Die kwaliteit van die gefermenteerde vis produk word gedeeltelik bepaal deur die fermentasie kondisies en die metaboliese aktiwiteit van die mikrobes teenwoordig. Die vinnige identifikasie van die mikrobes teenwoordig gedurende die fermentasie sal die seleksie van moontlike suursels om die versnelde produksie van hoë kwaliteit gefermenteerde vis produkte moontlik maak. Hierdie studie is dus onderneem om identifikasie vingerafdrukke vir bakteriee wat gei'soleer is van gefermenteerde vis produkte moontlik te maak. ‘n 1300 bp fragment van die 16S rRNA gene van elkeen van die bakteriee wat voorheen gei'soleer is, is suksesvol geamplifiseer deur die PCR tegniek. Die isolate sluit in stamme van die genera Bacillus, Staphylococcus, Sphingomonas, Kocuria, Brevibacillus, Cryseomonas, Vibrio, Stenotrophomonas en Agrobacterium. Die data kan dus gebruik word in die identifikasie van hierdie mikrobes as dit gei'soleer word van ander gefermenteerde vis produkte. Die vingerafdrukke kan ook gebruik word om die dominante mikrobiese populasies wat verantwoordelik is vir die kenmerklike kwalitatiewe veranderinge wat plaasvind in die vis produk gedurende die fermentasie, te identifiseer. Die mikrobiese samestelling van ‘n fermenterende vis produk bepaal gedeeltelik die kwaliteit van die eindproduk, daarom kan die gebruik van geselekteerde bakteriese suursels die versnelde produksie van ‘n mikrobies veilige gefermenteerde vis produk teweeg bring. ‘n Verdere doel van hierdie studie was om die produksie van ‘n gefermenteerde vis produk te versnel deur fyngemaakte forel met of geselekteerde melksuurbakteriee of met geselekteerde bakteriee met hoë proteolitiese aktiwiteit te inokuleer oor ‘n 30 dag fermentasie periode. Die melksuurbakteriee het ingesluit ‘n kombinasie van Lactobacillus plantarum, Lactococcus diacetylactis en Pediococcus cerevisiae, terwyl die bakterieë met hoë proteolitiese aktiwiteit stamme van Kocuria varians, Bacillus subtilis, twee stamme van Bacillus amyloliquefaciens en ‘n kombinasie van hierdie bakteriese stamme ingesluit het. Die kwaliteit van die gefermenteerde produk is bepaal deur die veranderinge in die pH, titreerbare suur (%TS) en vrye amino stikstof (VAS) vorming van die produk as effektiwiteits parameters te gebruik. Die data wat verkry is gedurende die fermentasie van die fyngemaakte forel het gedui daarop dat die geselekteerde suursels nie ‘n merkwaardige effek op die afname in pH in die produk oor ‘n 30 dag fermentasie periode het nie. Die melksuurbakteriee het nie ‘n merkwaardige effek op die %TS van die gefermenteerde vis produk gehad nie, terwyl dit geblyk het dat die teenwoordigheid van hierdie bakterieë die produksie van VAS in die produk belemmer het. Die bakteriee met hoe proteolitiese aktiwiteit het ‘n effense verhoogde %TS en ‘n hoër VAS inhoud in die gefermenteerde produk veroorsaak. Dit is ook bepaal dat die melksuurbakteriee en Kocuria varians, in teenstelling met die Bacillus spp. inokulums, nie die fermentasie kondisies goed oorleef het nie, moontlik as gevolg van die lae pH omgewing. Die teenwoordigheid van die suursel bakteriee in die fermenterende vis mengsel aan die einde van die fermentasie is ook suksesvol bepaal met die PKR-RFLP tegniek. Die gefermenteerde vis produk, verkry aan die einde van die fermentasie periode, het ‘n goeie aroma gehad en het goed vergelyk met soortgelyke kommersieel beskikbare gefermenteerde vis produkte. Die gebruik van verskillende mikrobiese suursels kan in die toekoms die produksie van ‘n diverse reeks hoë kwaliteit produkte wat plaaslik geproduseer en bemark kan word moontlik maak.

Thesis (MSc Food Sc)--Stellenbosch University, 2000.
ENGLISH ABSTRACT: Maas is a traditional fermented milk drink of the indigenous people of Southern Africa and can thus be used to uplift the nutritional status of the South African population, especially for the lower income groups. Furthermore, the problem of lactose intolerance among the Black population can also be addressed by the consumption of Maas. The objective of this study was to screen mesophylic lactic acid bacterial strains (25 in total) from the University of Stellenbosch Food Science Culture Collection for suitable metabolite production and then to produce traditional Maas with a starter culture combination that produces a distinctive acid and traditional flavour. The representative 25 single lactic acid starter strains were identified as Lactococcus lactis subsp. leetis biovar diacetylactis (12 strains), L. leetis subsp. leetis (four strains) and L. leetis subsp. cremoris (nine strains). These strains were inoculated into pasteurised full cream milk and activated for 8 h at 22°C. Pasteurised full cream milk was then inoculated with each of the activated starter strains, incubated at 22°C for 16 h and assessed for acid production abilities (pH = 4.6) under controlled time-temperature conditions. The results of this study showed that nine of the single strains, L. lactis subsp. leetis biovar diacetylactis (S1, S2, S3 and S5), L. teetis subsp. lactis (S13, S15 and S16) and two L. leetis subsp. cremoris strains (S17 and S22), produced sufficient acid, rendering them suitable for the use as starters in the production of traditional Maas. A pH range of 4.3 - 5.1 was reached by the nine single strains after 16 h at 22°C. Two-strain starter combinations were then formed by combining the most suitable single L. leetis subsp. leetis biovar diacetylactis, L. lactis subsp. lactis and L. lactis subsp. cremoris strains, respectively. From the data, it was concluded that acceptable Maas could be produced with four two-strain combinations (S3S 17, S3S22, S5S17 and S5S22). This selection was again based on suitable acid and metabolite production, as well as on sensory evaluation of the final product. These four two-strain combinations produced sufficient acid to reach a pH in the 4.6 - 4.8 range, and showed a high metabolite concentration for the most suitable compounds and formed a thick, smooth and creamy body texture after 16 h at 22°C. Three-strain combinations formed between the two-strain starter combinations and L. leetis subsp. teetis strains (813, 815 and 816), were also evaluated. With these combinations a lack of a pronounced Maas flavour was found. Thus, it was decided to add aroma producing strains of the species Leuconostoc mesenteroides subsp. dextranicum (strain L1) and L. mesenteroides subsp. citrovorum (strain L2) to the three-strain combinations. Four culture combinations (A, B, C and D) were then formed by combining the selected Leuconostoc strains (L1 and L2) with the most suitable Lactococcus strains (83,817,813 and 822). These combinations produced sufficient acid to reach the pH 4.5 - 4.6 range after 14 h at 22°C. Acetaldehyde was the major flavour metabolite formed in the Maas made with these four combinations, with concentrations ranging between 26.6 - 89.3 mg.l ̄ ¹, while other flavour metabolites (ethanol, acetone, diacetyl and 2-butanone) were present at lower concentrations. It was found that three of the four culture combinations (A, C and D) were characterised by a superior, but delicate flavour and a typical characteristic Maas body texture. Fruit flavoured Maas was subsequently prepared with the three most suitable culture combinations (A, C and D) using 11 flavours and a sensory evaluation performed. The statistically evaluated data showed that the appearance, smoothness, flavour intensity, sweetness and overall acceptability were influenced by the type of fruit flavour and the culture combination. Fruit flavour 4 (banana) was the most preferred flavour. The sensory panellists also indicated that the culture combination C gave the best overall acceptability over a three week study period. Data on the shelf-life study of natural unflavoured Maas, prepared with the three culture combinations (A, C and D), showed that the Maas still had an acceptable appearance, taste and good microbiological quality after 15 d at refrigerated temperatures.
AFRIKAANSE OPSOMMING: Maas is 'n tradisionele gefermenteerde melkdrankie onder die inheemse bevolking van Suid-Afrika en kan gebruik word om die voedingstatus van die Suid-Afrikaanse bevolking te verhoog, veral vir die laer inkomste groepe. Bowendien, kan die probleem van laktose intoleransie onder die Swart gemeenskap ook aangespreek word deur die verbruik van Maas. Die doel van hierdie studie was om enkelstam mesofiliese melksuur bakterieë (25 in totaal) van die Universiteit van Stellenbosch Voedselwetenskap Kultuur Versameling te ondersoek vir geskikte metaboliet produksie en tradisionele Maas met 'n kenmerkende suurheid en tradisionele geur met 'n geskikte kultuur kombinasie te produseer. Die toonaangewende 25 enkelstamme is Lactococcus lactis subsp. leetis biovar diacetylactis (12 stamme), L. lactis subsp. lactis (vier stamme) en L. lactis subsp. cremoris (nege stamme). Hierdie stamme was in gepasteuriseerde volroom melk geïnokuleer en geaktiveer vir 8 h teen 22°C. 'n Inokulum van die onderskeie geaktiveerde stamme is hierna in gepasteuriseerde volroom melk geplaas, vir 16 h teen 22°C geïnkubeer en hul vermoë om suur te produseer (pH = 4.6) onder beheerde tyd-temperatuur kondisies is bepaal. Die resultaat van die studie het aangedui dat nege enkelstamme, naamlik L. leetis subsp. lactis biovar diacetylactis (S1, S2, S3 en S5), L. lactis subsp. leetis (S13, S15 en S16) en twee L. leetis subsp. cremoris (S 17 en S22), geskikte suurheidsvlakke vir die produksie van Maas bereik het. 'n pH vlak van 4.3 - 5.1 is na 16 h teen 22°C deur hierdie nege enkelstamme bereik. Twee-stam kombinasies is onderskeidelik gevorm tussen die geskikte enkel L. lactis subsp lactis biovar diacetylactis, L. lactis subsp. lactis en L. lactis subsp. cremoris stamme. Die gevolgtrekking gemaak uit die data, is dat aanvaarbare Maas voorberei kan word met vier van die twee-stam kombinasies (S3S17, S3S22, S5S17 en S5S22) op grond van suurvorming, metaboliet produksie en sensoriese evaluasie. Hierdie vier kombinasies het genoegsame suur geproduseer om 'n pH vlak van 4.6 - 4.8 bereik, hoë metaboliet konsentrasies geproduseer en 'n dik, gladde en romerige tekstuur aangeneem na 16 h teen 22°C. Drie-stam kombinasies is gevorm tussen die onderskeie twee-stam kombinasies en L. lactis subsp. lactis stamme (813,815 en 816) en ook geëvalueer. Die tekort aan 'n skerp Maas geur in die drie-stam kombinasies het daartoe gelei dat Leuconostoc mesenteroides subsp. dextranicum (stam L1) en L. mesenteroides subsp. citrovorum (stam L2) bygevoeg is. Vier kultuur kombinasies (A, B, C en D) is gevorm deur die geselekteerde Leuconostoc stamme (L1 en L2) te kombineer met die mees gepaste Lactococcus stamme (83, 817, 813 en 822). Hierdie kombinasies het genoegsame suur geproduseer wat 'n pH vlak van 4.5 - 4.6 na 14 h teen 22°C bereik het. In die Maas wat met bovermelde kombinasies gemaak is, was die asetaldehied die mees geproduseerde geur metaboliet teen konsentrasies van 26.6 - 89.3 mg.l ̄ ¹. Ander geur metaboliete (etanol, asetoon, diasetiel, 2-butanoon) is in laer konsentrasies geproduseer. Daar is gevind dat drie uit die vier kultuur kombinasies (A, C en D) 'n superieur, delikate geur wat 'n tipies karakteristiek van die Maas gehad het. Vrugte gegeurde Maas geproduseer met die drie kultuur kombinasies (A, C en D) deur 11 geursels te gebruik, is sensories geëvalueer. Die statistiese geëvalueerde data het getoon dat die voorkoms, gladheid, geur intensiteit, soetheid en die algehele aanvaarbaarheid beïnvloed is deur die tipe vrugte geursels en die kultuur kombinasies. Die vrugte geursel 4 (piesang) het voorkeur geniet. Die sensoriese paneellede het ook aangedui dat kultuur kombinasie C die algehele mees aanvaarbare Maas geproduseer het oor die studie periode van drie weke. Data van die rakleeftyd van die natuurlike ongegeurde Maas wat geproduseer is met die drie kultuur kombinasies (A, C en D) het aangedui dat die Maas na 15 d by yskas temperatuur steeds 'n aanvaarbare voorkoms, smaak en goeie mikrobiologiese kwaliteit gehad het.

Peanuts are a valuable agricultural commodity and roasted peanut flavor is the driving force for consumer purchase and consumption. The development of off-flavors is a major concern to the peanut industry and physiological differences (i.e. oil and sugar content) among the different maturity classes can influence the presence and/or absence of specific flavors. Fruity fermented (FF) is a common off-flavor found in peanuts and is developed when peanuts are cured at excessive temperatures (>35ºC). Previous literature has characterized FF off-flavor using descriptive sensory analysis; however, there is little information on FF off-flavor using consumer evaluation. The peanut plant has an indeterminate flowering pattern meaning a range of maturities are present at harvest and the immature and mature peanuts differ in roasting and flavor quality. Immature peanuts tend to have more FF off-flavor than mature peanuts which results in a FF distribution within large peanut lots. The flowering pattern and heterogeneous distribution of immature and mature seed make it challenging to obtain an accurate determination of FF off-flavor in a bulk lot. Establishing links between flavor and volatile flavor compounds can be obtained by using sensory and instrumental analyses. Currently, there is little research published on the volatile components that contribute to naturally occurring FF off-flavor. The objectives of this research were to: i) characterize consumer?s perception of FF off-flavor, ii) measure the variability and determine the FF distribution in bulk lots, iii) and identify the volatile compounds responsible for naturally occurring FF off-flavor using sensory and instrumental analyses. Descriptive sensory analysis was conducted to determine the no FF and FF samples used for the consumer study. Two-hundred and eight consumers evaluated a control (no FF off-flavor), low (1.0 FF) intensity, and a high (3.0 FF) intensity using two different scaling techniques: category and line scales. Results indicated FF off-flavor negatively impacts consumer acceptance of peanuts and the line scales were more sensitive and showed more differences among the samples compared to the category scale. The second study investigated the distribution of FF off-flavor in peanut lots and the results indicated that FF intensity varied from lot to lot and within a single bulk lot. Solvent assisted flavor evaporation (SAFE), solidphase microextraction (SPME), gas chromatography-olfactometry (GC-O), gas chromatography-mass spectrometry (GC-MS), and model systems were conducted to identify the compounds responsible for naturally occurring FF off-flavor. Volatile analysis indicated that ethanol and the esters previously reported as causing FF off-flavor were not detected in natural FF samples by solvent extractions; however, they were present in natural and artificially created Georgia Green and Flavor Runner 458 samples by headspace extractions. These findings emphasizes that the use of laboratory created samples should not be used to identify off-flavor sources in peanuts. Additionally, the use of analytical techniques to identify FF off-flavor in bulk lots cannot be achieved using ethanol or esters as indicators.

Three New Zealand marine species, hoki (Macruronus novaezealandiae), kahawai (Arripis trutta) and trevally (Pseudocaranx dentex) were used to develop model fermented fish sausage. The formulation comprised fish mince, carbohydrate, minced garlic and salt in a mass ratio of 1 (fish): 0.15: 0.05: 0.03, respectively. The carbohydrate source was cooked rice or glucose. (Endogenous lactic acid bacteria (LAB) failed to ferment rice). Folate was also added to the mixture as a factor. The mixtures were extruded into 50 mL plastic syringes, where the needle end of the barrel had been excised by lathe. The lubricated barrel was overfilled to 60 mL, capped with a layer of ParafilmTM and aluminium foil, sealed tightly by rubber band and incubated at 30°C. Over time the piston was progressively advanced to yield samples for microbiological, physical, and chemical analysis. Over 96 hours an increase in the LAB count was observed with a concomitant decrease in pH. After fermentation was complete, the samples contained around 8.77 log cfu LAB g-1 with the pH range from 4.38 to 5.08. The microbiological and pH behaviour of each species varied between preparations. Hardness, adhesiveness, springiness and cohesiveness of the treatments increased with fermentation, except for hoki. The treatments showed different colour characteristics with fermentation. The light reflectance (L* values) of the trevally and kahawai treatments increased, while the a* (redness) and b* (yellowness) values decreased. Hoki exhibited smaller colour changes except for yellowness, which increased markedly. Proteolysis, measured colorimetrically by soluble peptide bonds, was greatest for trevally. Lipid oxidation, measured by the thiobarbituric acid method, was least for hoki, notably the species with the lowest fat content. Biogenic amines, which are a general quality indicator of fermented products, increased during fermentation. The trevally treatment generated the highest concentration of amines, but these values were lower than those reported for fermented fish sausage in Southeast Asia. Notably there were no important difference between folate treatments and those without folate. The results point to commercial opportunities and further research with New Zealand marine species, especially trevally. To improve the product quality and to show geographical exclusivity, further research could be done by using starter culture, and a New Zealand staple carbohydrate source such as kumara and potato, and spices and herbs which are commonly used in New Zealand, such as rosemary, thyme and sage or specific to New Zealand, such as horopito. In addition, sensory studies should also be performed before the products could be tested in the market.

First grade and second grade Nampla, commercially produced Thai fish sauces, were analyzed for their chemical and microbiological composition. First grade commercially produced Nampla contained higher amounts of total nitrogen, formol nitrogen, free and total amino acids compared to second grade sauce. Most of the essential amino acids were present in both grades of sauces. Low microbial counts of halotolerant microorganisms were observed in both sauces. The use of trypsin and chymotrypsin to accelerate the rate of fish sauce fermentation produced from herring, one of the underutilized fish species in Quebec, was investigated. Results showed that supplementation with trypsin and chymotrypsin increased significantly the rate of proteolysis, the amounts of total nitrogen, formol nitrogen and free amino acids in the final fish sauces (p 0.05). (Abstract shortened by UMI).

Thesis (MSc Food Sc )--Stellenbosch University, 2000.
ENGLISH ABSTRACT: Fermented fish products are popular food products mainly consumed and produced in Southeast Asia. These products are not produced in South Africa, and those available to the public are imported. The main action during the production and fermentation of this sort of product, is that of proteolysis, either by the bacteria or enzymes naturally present in the fish. The prevalent microbes present in six fermented fish samples from Bangkok (Thailand) and seven from Khon Kaen (Thailand), were determined, and using numerical methods, clustered into similarity groups using the calculated dendrogram .distance (Do) technique to determine their relation to reference strains. Forty-seven different bacterial strains were isolated, but no yeasts, moulds or lactic acid bacteria were found. Five Gram-negative, oxidase-positive species, five different Staphylococcus species and nine different endospore-forming species of the genus Bacillus, were isolated and identified using the API systems. The data indicated that members of the genus Bacillus were the prevalent organisms in all the products examined. The isolates were also scanned for general enzyme activity using the API Zym technology, and the production of proteases was investigated using the Standard Methods Caseinate and the Universal Protease Substrate methods. It was found that most of the isolated organisms produced protease, which is of major importance in the production of fermented fish products. Proteolytic cultures from the fermented fish products, as well as lactic acid starters, were used in the production of a fermented fresh water fish product. Production parameters including: glucose, inoculum, moisture content and incubation time, were evaluated in order to select optimum fermentation conditions. Fermentation efficiency was determined by measuring the final pH, titratable acid and the free amino nitrogen content. Optimum efficiency was obtained with 5% (w/w) added glucose at a moisture level of 150 ml water per 100 g fish. A factorial design (3 x 3 x 3) was used to indicate viable trends to facilitate optimisation of the fermentation process. The main effects, two-factor and three-factor interactions were calculated. Optimum trends obtained were a glucose concentration of 5% (wlw) , inoculum concentration of 1x10⁸ kve.ml ̄ ¹, an incubation period of 15 days and temperature of 30°C. Three lactic acid starters (226 - Lactobacillus plantarum, 140 - Lactococcus diacetylactis and 407 - Pediococcus cerevisiae) were selected as they produced some of the best fermentation results and are safe to use in food. It was found that a combination of all three strains (226, 140 and 407) yielded the best results. By using the above parameters, an acceptable product was produced in terms of consistency, colour and aroma. Further studies need to be conducted to optimise the safety of the product as well as the flavour, both chemically and sensorically optimisation of the product.
AFRIKAANSE OPSOMMING: Gefermenteerde visprodukte is populere voedselprodukte in die lande van Suidoos-Asie. Die produkte word nie in Suid-Afrika geproduseer nie, maar slegs ingevoer. Die hoof aksie tydens die fermentasie proses is proteolise deur die bakteriee en ensieme wat natuurlik teenwoordig is in vis. Die oorheersende mikrobes teenwoordig in ses gefermenteerde vis produkte van Bangkok (Thailand) en sewe van Khon Kaen (Thailand), is bepaal. Numeriese metodes is gevolg om die isolate in groepe te sorteer en te groepeer deur gebruik te maak van die berekende dendrogram afstand (Do) tegniek om hul verwantskap ten opsigte van die verwysingsorganisme te bepaal. Sewe-en-veertig verskillende bakteriee is ge·isoleer, maar geen fungi of melksuurbakteriee is ge·identifiseer nie. Vyf Gram-negatiewe, oksidase-positiewe spesies, vyf verskillende Staphylococcus spesies en nege verskillende endospoorvormende spesies van die genus Bacillus, is geisoleer en ge·identifiseer deur gebruik te maak van die API CHB sisteme. Die data het getoon dat lede van die genus Bacillus die oorheersende organismes was. Die isolate is daarna ondersoek vir algehele ensiemaktiwiteit deur van die API Zym tegnologie gebruik te maak. Daar is veral klem gelê op die protease aktiwiteit en dit is gemeet deur van die "Standard Methods Caseinate Agar" metode asook die "Universal Protease Substrate" metodes gebruik te maak. Daar is gevind dat die oorgrote meerderheid organismes proteolitiese ensieme produseer wat belangrik is in die produksie van gefermenteerde visprodukte. Kulture wat ge·isoleer is uit gefermenteerde visprodukte asook melkssuurkulture is gebruik vir die produksie van 'n gefermenteerde varswater visproduk. Produksieparameters insluitende: glukose-, inokulum- en voginhoud asook inkubasie tyd is ondersoek om die optimum fermentasie kondisies te bepaal. Optimum effektiwiteit is gevind by 'n 5% glukose konsentrasie en vogvlakke van 150 ml water per 100 9 vis. 'n Faktoriale ontwerp (3 x 3 x 3) is gebruik om die optimum kondisies te bepaal. Die hoof effekte asook die twee faktor en drie faktor interaksies is bereken. Optimum neigings is gevind by 'n glukose konsentrasie van 5%, inokulum konsentrasie van 1x10⁸ kve.ml ̄ ¹, 'n inkubasie tydperk van 15 dae en temperatuur van 30°C. Drie melksuurbakteriee (226 - Lactobacillus plantarum, 140 - Lactococcus diacetylactis en 407 - Pediococcus cerevisiae) is gekies aangesien hulle die beste resultate gelewer het en veilig vir gebruik in voedselprodukte is. Daar is gevind dat die drie melksuurkulture saam in kombinasie die beste fermentasie resultate opgelewer het. Deur gebruik te maak van die bogenoemde fermentasie kondisies, kon 'n aanvaarbare produk, in terme van kleur en geur, gelewer word. Verdere studies moet gedoen word om die veiligheid asook die geur, chemies asook sensories, te optimiseer.

Thesis (MSc Food Sc)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: A wide variety of traditionally and commercially fermented milks are commonly consumed in various countries of Sub-Saharan Africa. Commercially fermented milk is produced on an industrial scale according to well-managed, standardised production processes and starters are used to initiate fermentation. Traditionally fermented milk is prepared domestically and fermentation occurs spontaneously at ambient temperatures. Lactic acid bacteria (LAB) are responsible for milk fermentation during which they convert the milk carbohydrates to lactic acid, carbon dioxide, alcohol and other organic metabolites. Acetic acid bacteria (AAB), yeasts and mycelial fungi have also been isolated from fermented milks. In this study the microbial consortium present in three traditionally fermented milks, namely omashikwa from Namibia, masse from Mozambique and chekapmkaika from Uganda and two commercially fermented milks, namely chambiko from Malawi and omaere from Namibia, were isolated and enumerated on six different selective media that included MSR + C (specific for lactobacilli), KCA + TTC (specific for lactococci), KCA + V (specific for leuconostocs), MRS + E (specific for AAB), MEA (specific for mycelial fungi) and YPD (specific for yeasts). No significant differences were found between the enumeration values obtained for the three chambiko samples, as well as for enumeration values obtained for the two omaere samples on each of the selective media, indicating low sample variance. Significant differences between enumeration values obtained for the three omashikwa samples were found on all six selective media. Significant differences between enumeration values of the three masse samples and both the chekapmkaika samples were also observed on the selective media. In addition to this, significant differences were observed between average enumeration values obtained for each media between the masse and chekapmkaika, the chambiko and omaere, as well as when the traditional and commercial milks were compared. According to the average enumeration values obtained on each media selective for LAB, the highest bacterial counts were detected on KCA + TTC medium for omaere (2.3 x 106 cfu.ml-1), KCA + V for chambiko (1.8 x 105 cfu.ml-1), KCA + TTC for omashikwa and MRS + C for masse and chekapmkaika (6.2 x 106 and 2.0 x 103 cfu.ml-1, respectively). After isolation and enumeration of the microbes present in each milk, bacterial isolates on the media selective for LAB and AAB were obtained according to the Harrison Disk method. These isolates were identified by amplifying a 1.5 kilobase (kb) part of the 16S ribosomal RNA (rRNA) gene using the polymerase chain reaction (PCR), followed by DNA sequencing. The isolates were identified by comparing the sequences obtained to sequences listed in the NCBI database using the BLAST algorithm and searching for the closest relative. The main LAB group present in the omaere was lactococci (94%), in chambiko and chekapmkaika it was lactobacilli (30% and 45%, respectively), in omashikwa it was enterococci (43%) and in masse it was leuconostocs (68%). The same microbial species were present on a number of the selective media used in this study. Lactococcus spp., Enterococcus spp. and Lactobacillus spp. were isolated from MRS + C, KCA + TTC, KCA + V and MRS + E and Leuconostoc spp. were isolated from MRS + C, MRS + E and KCA + V. Hygienic standards during traditional milk fermentation is often poor and, therefore, microbial contaminants were isolated from the traditional milk and these included Acinetobacter johnsonii and Klebsiella pneumoniae from KCA + V, Mesorhizobium loti, Acinetobacter radioresistens, Escherichia coli, Staphylococcus spp., Kluyvera georgiana, Enterobacter spp. and Klebsiella oxytoca from KCA + TTC, Staphylococcus spp. from MRS + C and Bacillus spp. from MRS + E. Since the media used for the isolation of the LAB and AAB in this study were not selective further identification of the enumerated microbes is of importance for the identification of the microbial groups present in each fermented milk. The data obtained in this study clearly shows that fermented milks from Sub-Saharan Africa vary significantly from each other in terms of microbial numbers, microbial diversity and the dominant microbial groups present. The microbial diversity of the traditionally fermented milks was more diverse than the microbial diversity of the commercially fermented milks. LAB strains isolated from these traditionally fermented milks can be used to develop novel starters and as a result new commercially fermented dairy products with unique aromas, tastes and characteristics can be produced.
AFRIKAANSE OPSOMMING: 'n Wye verskeidenheid tradisioneel en kommersieel gefermenteerde melk produkte word algeneem verbruik in verskeie lande van Sub-Sahara Afrika. Kommersieel gefermenteerde melk word geproduseer op groot skaal, deur deeglik bestuurde gestandardiseerde produksieprosesse en 'n beginkultuur word gebruik om fermentasie te inisieer. Tradisioneel gefermenteerde melk word tuis gemaak en fermentasie gebeur spontaan by kamertemperatuur. Melksuurbakterieë (MSB) is verantwoordelik vir melkfermentasie waartydens die bakterieë koolhidrate omskakel na melksuur, koolstofdioksied, alkohol en ander organiese sure. Asetaatsuurbakterieë (ASB), giste en miseliale fungi is ook al van gefermenteerde melk geïsoleer. In hierdie studie is die mikrobiese konsortium teenwoordig in drie soorte tradisioneel gefermenteerde melk, naamlik omashikwa van Namibië, masse van Mosambiek en chekapmkaika van Uganda en twee soorte kommersieel gefermenteerde melk, naamlik chambiko van Malawi en omaere van Namibië, geïsoleer en getel op ses verskillende selektiewe groeimedia insluitend MRS + C (spesifiek vir lactobacilli), KCA + TTC (spesifiek vir lactococci), KCA + V (spesifiek vir leuconostocs), MRS + E (spesifiek vir ASB), MEA (spesifiek vir miseliale fungi) en YPD (spesifiek vir giste). Geen betekenisvolle verskille is gevind tussen die mikrobiese tellings verkry vir die drie chambiko monsters nie, sowel as tussen die mikrobiese tellings verkry vir die twee omaere monsters, op elk van die selektiewe groeimedia, wat dui op lae monster variansie. Betekenisvolle verskille is gevind tussen die mikrobiese tellings verkry vir die drie omashikwa monsters op al ses selektiewe groeimedia. Betekenisvolle verskille is ook waargeneem tussen die mikrobiese tellings van die drie masse monsters en beide die chekapmkaika monsters op die selektiewe groeimedia. Daarbenewens is betekenisvolle verskille waargeneem tussen gemiddelde mikrobiese tellings verkry vir elke groeimedium tussen die masse en chekapmkaika, die chambiko en omaere asook toe die tradisionele en kommersiële melk produkte met mekaar vergelyk is. Volgens die gemiddelde mikrobiese tellings verkry op elk van die groeimedia selektief vir MSB, is die hoogste mikrobiese telling waargeneem op KCA + TTC medium vir omaere (2.3 x 106 kve.ml-1), KCA + V vir chambiko (1.8 x 105 kve.ml-1), KCA + TTC vir omashikwa en MRS + C vir masse en chekapmkaika (6.2 x 106 en 2.0 x 103 kve.ml-1, respektiewelik). Na die isolasie en tel van die mikrobes teenwoordig in elke melk is bakteriese isolate op die media selektief vir MSB en ASB verkry volgends die Harrison Disk metode. Hierdie isolate is geïdentifiseer deur amplifikasie van „n 1.5 kilobasis (kb) gedeelte van die 16S ribosomale RNS (rRNS) geen deur gebruik te maak van die polimerase kettingreaksie gevolg deur DNS klonering. Die isolate is geïdentifiseer deur die gekloneerde insetsels se volgordes te vergelyk met volgordes beskikbaar op die NCBI webwerf deur van die BLAST algoritme gebruik te maak en die naas verwante insetsel op te spoor. Die hoof MSB groep teenwoordig in die omaere was lactococci (94%), in chambiko en chekapmkaika was dit lactobacilli (30% en 45%, respektiewelik), in die omashikwa was dit enterococci (43%) en in die masse was dit leuconostocs (68%). Dieselfde mikrobiese spesies was teenwoordig op verskeie van die selektiewe groeimedia gebruik in hierdie studie. Lactococcus spp., Enterococcus spp. en Lactobacillus spp. is geïsoleer van MRS + C, KCA + TTC, KCA + V en MRS + E en Leuconostoc spp. is geïsoleer van MRS + C, MRS + E en KCA + V. Higiëniese standaarde tydens tradisionele melkfermentasie is dikwels swak en dus is mikrobiese kontaminante geïsoleer van die tradisionele melk produkte insluitend Acinetobacter johnsonii en Klebsiella pneumoniae van KCA + V, Mesorhizobium loti, Acinetobacter radioresistens, Escherichia coli, Staphylococcus spp., Kluyvera georgiana, Enterobacter spp. en Klebsiella oxytoca van KCA + TTC, Staphylococcus spp. van MRS + C en Bacillus spp. van MRS + E. Aangesien die media wat gebruik is vir die isolasie van die MSB en ASB in hierdie studie nie selektief was nie, is verdere identifikasie van die getelde mikrobes belangrik vir die identifikasie van die mikrobiese groepe teenwoordig in elke melk. Die data verkry in hierdie studie dui aan dat gefermenteerde melk produkte van Sub-Sahara Afrika betekenisvol van mekaar verskil in terme van mikrobiese getalle, mikrobiese diversiteit en die dominante mikrobiese groepe teenwoordig. Die mikrobiese diversiteit van die tradisioneel gefermenteerde melk produkte was meer divers as die mikrobiese diversiteit van die kommersieel gefermenteerde melk produkte. MSB spesies geïsoleer van hierdie tradisioneel gefermenteerde melk produkte kan gebruik word om nuwe beginkulture te ontwikkel en gevolglik kan nuwe kommersieel gefermenteerde suiwelprodukte met unieke aromas, smake en eienskappe geproduseer word.

Master of Science
Food Science
Terry Houser
The objective of this research was to evaluate the effect of natural nitrites on objective color of vacuum packaged fresh pork. Sections of longissimus dorsi muscle (approximately 18 cm) were injected with solutions containing 0, 3, 6, 9 or 12 ppm of natural nitrite. Sections were sliced into chops (2.54 cm) and individually vacuum packaged. Raw chop surface L*, a* and b* values were measured at 1, 5, 15 and 30 days post packaging. At 1, 15 and 30 days post packaging chops were cooked and surface L*, a* and b* values were measured. Hue and Chroma values were calculated for all color measurements. Linear and quadratic contrasts were evaluated on treatments for all measured and calculated color values. A linear (P<0.05) increase was detected on the L* values for days of vacuum storage treatment, all other raw color measurements and calculations for levels of natural nitrite and days of vacuum package storage were found to be quadratic (P<0.05). Cooked L* and Hue values for days of vacuum storage were found to decrease linearly (P<0.05), all other days of storage and levels of nitrite treatments were found to be quadratic (P<0.05) in relationship to the measured and calculated cooked color values. All raw chops containing nitrite had higher a* and Chroma values at all evaluation days than those containing no added nitrite. Raw chops containing nitrite had lower L*, higher b* and Hue values than the 0 ppm chops (P<0.05). Raw chops containing natural nitrite were darker, redder, more yellow and more intense in color than those without nitrite. The longer the chops were vacuum packaged and then cooked, the lower the L* values were (P<0.05). Cooked chops containing nitrite were redder, less yellow and lower in Hue and Chroma values than cooked chops with no added nitrite P(<0.05). These results indicate that low levels of nitrite can alter fresh and cooked pork color during vacuum storage. To balance the increased redness and darkness of the raw chops with the increased redness of the cooked chops, 3 ppm of natural nitrite was found to be the optimal treatment.

Thesis (MSc)--Stellenbosch University, 2002.
ENGLISH ABSTRACT: Developing countries such as South Africa are in dire need of nutritionally adequate dairy food and beverage sources that are ambient stable due to minimal access to refrigeration. One such product is Kefir, a naturally fermented milk beverage that originated in Caucasian China many centuries ago. The microorganisms responsible for fermentation of the milk are held together in a carbohydrate matrix in the form of small grains. These grains are then removed from the beverage prior to consumption, and added to fresh milk for new fermentations. This beverage holds great potential for large scale development due to the self-propagating nature of the grains, the lack of sophisticated equipment and knowledge necessary for production, and the appealing sensory characteristics of this beverage. This study was therefore performed as an initial investigation to determine the optimum fermentation conditions for large-scale grain production and optimal sensory appeal. Kefir grain production was found to be proportional to incubation temperature in the range studied (18°, 22°, 25° and 30°C), with maximum grain biomass increases of 500% for the Kefir incubated at 30°C over the 10 d trial. During fermentation of Kefir grains in milk, lactic acid and other metabolites are produced. Lactic acid results in coagulation of the milk, necessary to provide the characteristic texture and flavour of Kefir, as well as exerting a preservative effect. Lactic acid production was found to be strongly proportional to both incubation temperature and inoculum concentration. The samples containing 2% (w/v) Kefir grain inoculum concentration that were incubated at 25°C for 24 h were found to have optimum lactic acid levels for good quality Kefir (pH of 4.4 - 4.6 and TA of 1.0 - 1.15%). The other metabolites produced during Kefir fermentation are responsible for the specific flavour of Kefir, and include acetaldehyde, diacetyl, ethanol, acetone and 2-butanone. These compounds were studied using headspace gas chromatography over the fermentation period, which yielded good resolution and separation of all these compounds, however, only acetaldehyde, ethanol and acetone were found to be major metabolites in this study, These analytical results were then further compared to sensory results for key identified attributes, as obtained from a trained sensory panel, to enable recommendations for optimum fermentation conditions to be made. The studied attributes included sourness, sweetness, butteriness, creaminess, yoghurt flavour, cowiness, effervescence, yeastiness, smoothness and overall acceptability. It was apparent from this study that correlations between analytical and sensory data could be drawn, and that panellists were particularly accurate in detecting the attribute sourness resulting from the accumulated lactic acid in the Kefir. Overall acceptability also seemed to be intricately linked to the attribute creaminess, hence the regular literature references to full-cream Kefir as optimum for best sensory appeal. From this study, it was evident that Kefir with optimal sensory appeal is obtained with incubation for 18 h at moderate temperatures (22° or 25°C) and grain inoculum concentrations (0.8% w/v).
AFRIKAANSE OPSOMMING: In ontwikkelende lande soos Suid-Afrika, bestaan daar 'n groot behoefte aan voedsame suiwelprodukte wat stabiel is by kamer temperatuur aangesien 'n groot deel van die bevolking beperkte toegang tot verkoelingsfasiliteite het. Een so 'n produk is Kefir, 'n natuurlike gefermenteerde suiwelproduk wat sy oorsprong eeue gelede in China gehad het. Die mikroorganismes wat verantwoordelik is vir die fermentasie, is saamgebind in 'n koolhidraat matriks in die vorm van klein korrels. Hierdie korrels word verwyder uit die drankie voordat dit gedrink word, en word dan weer by vars melk bygevoeg vir 'n verdere fermentasie. Hierdie gefermenteerde produk het baie potensiaal vir massa-produksie, omdat die korrels natuurlik vermeerder, geen gesofistikeerde toerusting of kennis nodig is nie, en die finale produk hoogs aanvaarbare sensoriese eienskappe het. Die doel van die studie was om 'n inleidende ondersoek uit te voer om die optimum fermentasie toestande vir massakweking van korrels en die mees aanvaarbare sensoriese eienskappe te bepaal. Uit hierdie studie is gevind dat Kefirkorrel vermeerdering proporsioneel is tot die verhoging in inkubasie temperatuur in die gebied 18°, 22°, 25° en 30°C, met maksimum biomassa toenames van tot 500% vir Kefir wat vir 10 dae by 30°C geïnkubeer was. Gedurende fermentasie van Kefirkorrels in melk, word melksuur en ander metaboliete gevorm. Melksuur lei tot die verlaging van die pH van die melk, en veroorsaak stolling, wat noodsaaklik is vir die kenmerkende tekstuur en geur van Kefir, maar dien ook as 'n preserveermiddel. Daar is ook gevind dat melksuur produksie 'n direkte verband het met die inkubasie temperatuur en inokulum konsentrasie. Die monsters met Kefirkorrel inokulum konsentrasie van 2% (miv) wat vir 24 h by 25°C geïnkubeer is, het die optimale melksuur konsentrasies vir goeie kwaliteit Kefir bevat (pH van 4.4 - 4.6 en TA van 1.0 - 1.15%). Ander metaboliete wat belangrike geurkomponente van Kefir is, is asetaldehied, diasetiel, etanol, asetoon en 2-butanoon. Hierdie metaboliete is bepaal en geëvalueer met bodamp gaschromatografiese tegnieke gedurende die fermentasie, wat 'n goeie resolusie en skeiding gelewer het. In hierdie studie is slegs asetaldehied, etanol en asetoon as hoof Kefir metaboliete gevind. Die analitiese data is verder vergelyk met die sensoriese data van die hoof sensoriese komponente, soos bepaal deur 'n opgeleide sensoriese paneel, om die mees gunstigde fermentasie parameters te bepaal. Die geëvalueerde eienskappe was suurheid, soetheid, botterigheid, romerigheid, joghurt geur, koeismaak, gas inhoud, gisagtigheid, gladheid en algehele aanvaarbaarheid. Uit hierdie data is gevind dat daar wel 'n sterk korrelasie bestaan tussen die analitiese en sensoriese resultate, en dat paneellede in staat was om die suurheid, as gevolg van die gevormde melksuur, te bepaal. Algehele aanvaarbaarheid is definitief gekoppel aan romerigheid, daarom word volroommelk Kefir verkies bo die wat met afgeroomde melk berei is. Die data uit hierdie studie het ook getoon dat Kefir met optimale sensoriese eienskappe verkry is na 'n inkubasietyd van 18 h by "matige temperature" (22° of 25°C) en 'n Kefirkorrel inokulum van 0.8% (mIv).

A challenge study to validate a 5 log10 CFU/g reduction of non-O157 Shiga-toxin producing Escherichia coli (STEC) in dry fermented sausage (DFS) was performed. A 4.49 ± 0.474 log10 CFU/g was achieved over two trials. The results indicated that the process was not effective in reducing the pathogen to the level required of most pathogens by the USDA. Lactobacillus salivarius L28 (L28) was screened in vitro for the ability to inhibit STEC utilizing the paper disk diffusion method. This strain is a known bacteriocin producer. The results revealed that L28 would be a good candidate for use as a protective culture as large zones of inhibition were noted against the STEC. No zones of inhibition were noted against the commercial starter culture; therefore, it would not adversely impact the quality of the DFS. The supplementary L28 strain was added to a commercial starter culture to provide an additional hurdle in the protection against STEC. The sausage trial showed the additional strain did not offer a significant difference in reduction of the pathogen (p > 0.05). Further study will be required before L28 could be considered for use as a bioprotective culture.

Thesis (PhD Food Sc)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: The fermentation of milk has been known for millennia and leads to nutritious and prolonged shelf-life dairy products. In Southern Africa, traditional fermented dairy products have the same value as local staple foods and are consumed as a part of or as a whole meal. However, the retail price and the technology make many commercialised fermented dairy products unaffordable to the majority of the population. There is thus a need for a healthy nutritious low-cost easily prepared fermented dairy product. A product that could be the answer to the above need, is Kefir. The principle advantage is that the Kefir beverage is made from reusable Kefir grains, which unfortunately are not easily available and grow slowly. Kefir grains can only be obtained from pre-existing grains, which presents a problem in the marketing of the grains. A mass culturing technique was developed to produce large masses of grains but preparation of Kefir using these grains results in a product (MG Kefir) lacking in the sensory attributes of Traditional Kefir. Thus, the overall objective of this research was to determine the impact of environmental factors on the metabolic profiles of Kefir produced using different Kefir grains and this was then followed by the subsequent enrichment of Kefir prepared with mass cultured grains so as to obtain a Kefir beverage that has improved organoleptic qualities. To determine the impact of environmental factors Traditional and MG Kefir were prepared under controlled and uncontrolled conditions. Traditional Kefir was found to give the best beverage and was thus considered as the control. Under controlled conditions the optimum incubation temperature for the production of Kefir was 22ºC as over-acidification was observed at 25ºC. The metabolic profiles of both Traditional and MG Kefir showed that both contained acetaldehyde, ethanol, acetone, diacetyl and acetic acid. In addition, the metabolic profiles revealed that an inadequate ratio of diacetyl to acetaldehyde as well as the lack of ethyl acetate was responsible for the flavour defect in MG Kefir. In order to overcome this defect, citrate and ascorbate (0.015 % w.v-1) were added during Kefir fermentation to enhance the diacetyl and ethyl acetate production. This addition showed a positive impact on diacetyl but not on ethyl acetate production. Improvement of the overall flavour of Kefir was observed as the ratios of diacetyl to acetaldehyde were higher (0.21 – 0.5) in the samples with added citrate and ascorbate than in the samples without (0.12 – 0.17). The production of ethyl acetate in MG Kefir was enhanced by combining the effects of longer incubation (24 h + 18 h at 22ºC), addition of ethanol and acetic acid at 0.79% (m.v-1) and the addition of either Lactococcus lactis ssp. diacetylactis biovar diacetylactis 318 or Candida kefyr 1283. The best yields were obtained in samples containing C. kefyr 1283 and only added ethanol (9.22 mg.L-1), indicating that ethanol is an important factor in ethyl acetate production by Kefir starter strains and suggesting that the absence of ethyl acetate is an indication that the grains do not contain a yeast capable of producing sufficient ethyl acetate. During this investigation, the impact of ethyl acetate on the organoleptic quality of Kefir during storage at refrigerated and room temperatures were also studied. The results indicated that refrigerated Kefir contained up to 40 mg.L-1 of ethyl acetate and was not found defective and thus ethyl acetate was considered a positive contributor to Kefir flavour. This is of particular interest as ethyl acetate is a potent flavour compound at concentrations below 5 mg.L-1. Improvements of MG Kefir’s flavour were successful and will be of value for commercial Kefir production where the main aim is to optimise the flavour of Kefir. However, stabilising the grain microbial consortium was found to be important as it is responsible, over time, for both stable and acceptable Kefir. Acceptability of Traditional, MG and other Kefirs (Candi-Kefir and Lacto-Kefir) prepared with microbially stabilised MG was evaluated by 85 consumers. Results indicated that pH (r = 0.978; p < 0.05) was a significant driver of liking for flavour, especially for female consumers (r = 0.982; p < 0.05). In addition, three clusters, each characterised by different liking attributes were identified. Cluster I generally disliked all the products whereas slight acidic Kefir such as Candi-Kefir (7.63) and Lacto-Kefir (7.09) were preferred by Cluster III. Cluster II showed preference to Kefir with moderate acidity and high ethanol content. In that regard, Traditional Kefir obtained the best score (7.50) and MG Kefir the lowest score (4.87). The sensory study is of value as it led to the identification of the drivers of consumers liking by the different types of consumers. In the course of this project, near infrared reflectance spectroscopy was developed as a rapid method to estimate lactic and acetic acids, which are the organic acids responsible for acidity in Kefir, as well as pH and titratable acidity (TA). The results showed that the calibration models for lactic acid (RPD = 2.57 – 3.16), pH (RPD = 2.90) and TA (RPD = 2.60) were good for screening purposes (2 < RPD < 3); indicating that these models would show if the concentrations of lactic acid, the pH or the TA varied from the normal range. This study has demonstrated that the flavour of MG Kefir, prepared with enriched grains, was successfully improved and has provided some understanding on the preference liking of Kefir, an unknown fermented dairy product to South African consumers.
AFRIKAANSE OPSOMMING: Die fermentering van melk is al vir millennia bekend en lei tot voedsame suiwelprodukte met 'n verlengde raklewe. In Suidelike Afrika het tradisioneel gefermenteerde suiwelprodukte dieselfde waarde as plaaslike stapelvoedsels en word dit as 'n maaltyd of as deel van 'n maaltyd geëet. Die kleinhandelsprys en tegnologie van kommersieel gefermenteerde suiwelprodukte maak hierdie produkte egter onbekostigbaar vir die grootste deel van die populasie. Daar is dus 'n behoefte aan 'n gesonde, voedsame, goedkoop, maklik-om-te-berei gefermenteerde suiwelproduk. 'n Moontlike produk om aan die bogenoemde te voldoen is Kefir. Die hoof voordeel is dat die Kefir drankie van herbruikbare Kefirkorrels gemaak word, maar ongelukkig is hierdie korrels nie vrylik beskikbaar nie, en vermeerder dit stadig. Kefirkorrels kan net van reeds bestaande korrels verkry word wat problematies is vir die bemarking van hierdie korrels. 'n Massakwekingstegniek is ontwikkel vir die produksie van groot hoeveelhede korrels maar die voorbereiding van Kefir met hierdie korrels lei tot 'n produk (MG Kefir) wat sensories minder aanvaarbaar is as tradisionele Kefir. Die hoofdoel van hierdie navorsing was dus om die invloed van omgewingsfaktore op die metaboliese profiele van Kefir, berei deur gebruik te maak van verskillende Kefirkorrels, te bepaal. Dit is gevolg deur die verryking van Kefir berei van massagekweekte korrels om 'n Kefir drankie met verbeterde organoleptiese kwaliteite te verkry. Tradisionele en MG Kefir is voorberei onder gekontroleerde en ongekontroleerde toestande om die impak van omgewingsfaktore te bepaal. Die beste drankie is van tradisionele Kefir verkry en is dus beskou as die kontrole. Die optimum temperatuur vir die produksie van Kefir onder gekonroleerde toestande is 22ºC aangesien oor-versuring by 25ºC waargeneem is. Die metaboliese profiele van beide tradisionele en MG Kefir het gewys dat beide produkte asetaldehied, etanol, asetoon, diasetiel en asynsuur bevat. Die metaboliese profiele het verder gewys dat 'n onvoldoende diasetiel tot asetaldehied verhouding sowel as 'n tekort aan etielasetaat verantwoordelik was vir 'n geur defek in MG Kefir. Om hierdie defek te oorkom is sitraat en askorbaat (0.015% m.v-1) tydens Kefir fermentasie bygevoeg om diasetiel en etielasetaat produksie te verhoog. Hierdie byvoeging het 'n positiewe effek gehad op diasetiel produksie, maar nie op die produksie etielasetaat nie. 'n Verbetering in die algehele geur van Kefir is waargeneem aangesien die diasetiel tot asetaldehied verhoudings hoër (0.21 – 0.5) was in die monsters met bygevoegde sitraat en askorbaat as in die monsters daarsonder (0.12 – 0.17). Die produksie van etielasetaat in MG Kefir is verhoog deur die effekte van 'n verlengde inkubasie tydperk (24 h + 18 h by 22ºC), die byvoeging van etanol en asynsuur teen 0.79% (m.v-1) en die byvoeging van óf Lactococcus lactis ssp. diacetylactis biovar diacetylactis 318 óf Candida kefyr 1283 te kombineer. Die beste opbrengs is verkry in monsters wat C. kefyr 1283 en slegs etanol (9.22 mg.L-1) bevat het. Dit dui daarop dat etanol 'n belangrike faktor is vir etielasetaat produksie in Kefir beginstamme en wys moontlik op die afwesigheid van etielasetaat wat daarop dui dat die korrels nie 'n gis bevat wat bevoeg is om genoegsame hoeveelhede etielasetaat te produseer nie. Tydens hierdie ondersoek is die impak van etielasetaat op die organoleptiese kwaliteit van Kefir gedurende opberging by verkoelde- en kamertemperatuur ook bestudeer. Die resultate het gewys dat verkoelde Kefir tot 40 mg.L-1 etielasetaat bevat het sonder dat dit defektief was. Etielasetaat is dus beskou as 'n positiewe bydraer in terme van Kefir geur. Dit is van besondere belang aangesien etielasetaat 'n sterk geurkomponent teen konsentrasies laer as 5 mg.L-1 is. Verbeteringe in MG Kefir se geur was suksesvol en sal van waarde wees vir kommersiële Kefir produksie waar die hoofdoel die optimisering van Kefir geur is. Stabilisering van die korrels se mikrobiologiese konsortium is ook belangrik aangesien daar gevind is dat dit oor tyd verantwoordelik is vir stabiele en aanvaarbare Kefir. Die aanvaarbaarheid van tradisioneel, MG en ander Kefirs (Candi-Kefir en Lacto-Kefir), voorberei van mikrobiologies gestabiliseerde MG, is deur 85 verbruikers geëvalueer. Die resultate het aangedui dat pH (r = 0.978; p < 0.05) 'n belangrike faktor is in die bepaling van verbruikers se voorkeur van geur is, veral by vroulike verbruikers (r = 0.978; p < 0.05). Drie groepe, elk gekenmerk deur verskillende voorkeur en aanvaarbaarheid eienskappe, is verder geïdentifiseer. Groep I het oor die algemeen van geen van die produkte gehou nie en Groep III het die effense suur Kefirs soos Candi-Kefir (7.63) en Lacto-Kefir (7.09) verkies. Groep II het die Kefir met 'n matige suurheid en hoë etanolinhoud verkies. Tradisionele Kefir het die hoogste telling (7.50) en MG Kefir die laagste telling (4.78) behaal. Die sensoriese studie is van waarde aangesien dit gelei het tot die identifisering van die drywers van verbruikersvoorkeure deur die verskillende tipes verbruikers. Tydens hierdie projek is 'n naby-infrarooi reflektansie spektroskopiese metode ontwikkel vir die vinnige skatting van melk- en asynsuur, die organise sure wat verantwoordelik is vir die suurheid van Kefir, asook die pH en titreerbare suurheid (TS). Die resultate het getoon dat die kalibrasiemodelle vir melksuur (RPD = 2.57 – 3.16), pH (RPD = 2.90) en TS (RPD = 2.60) voldoende was vir siftingsdoeleindes (2 < RPD < 3). Dit dui daarop dat hierdie modelle sal aandui wanneer die konsentrasie van melksuur, pH of TS afwissel van die normale reeks. Hierdie studie het gewys dat die geur van MG Kefir, berei van verrykte korrels, suksesvol verbeter is en het ook gelei tot insigte in die voorkeur van aanvaarbaarheid van Kefir, 'n onbekende gefermenteerde suiwelproduk vir Suid-Afrikaanse verbruikers.

Ogi is a fermented food made from maize, sorghum or millet which serves as complementary food for infants and breakfast for adults in Nigeria, West Africa. This study characterized the microbial diversity of maize and sorghum grains and ogi produced by their natural fermentation in an attempt to understand the roles of the key microbial species and the impact of the population dynamics and selected species on changes in nutritional composition and aroma notes of ogi during fermentation. A combined approach of culture dependent and culture independent methods of analysis was applied to investigate the microbial community of grains and ogi from two different sources. Microbial diversity and viable populations varied with the source of the grain. Bacterial and fungal genera identified with the partial 16S rRNA and 26S rRNA sequence analysis respectively in maize and sorghum were Bacillus, Enterobacter, Micrococcus, Kytococcus, Pantoea, Staphylococcus, Amycolatopsis, Methanoculleus, Aspergillus, Penicillium, Eupenicillium, Acremonium, Schizosaccharomyces, Meyerozyma, Hyphopichia, and Pichia in maize grains; Enterococcus, Enterobacter, Pantoea, Bifidobacterium, Aspergillus, Cladosporum, and Penicillium in maize ogi; Enterococcus, Enterobacter, Pantoea, Aeribacillus, Cyanobacterium, Acinetobacter, Fusarium and Trametes in sorghum grains; and Pediococcus, Lactobacillus, Enterococcus, Bacillus, Cladosporum and Penicillium in sorghum ogi. Similar species were observed in both sources of maize while those of sorghum differed slightly. Predominant microbes included species of Enterobacteriaceae and moulds. Acetic acid bacteria were not identified as part of the diverse community. Following the predominance of moulds during the natural fermentation, preliminary screening was performed by PCR using specific biosynthetic gene primers to test whether they are the mycotoxin producing species. None of the genes tested were detected by PCR thus they may not be the toxin producing species. Starch, non-starch polysaccharide (NSP), phytate and phenolic compounds were determined in the grains and respective ogi to ascertain the levels of these nutritionally important components in the naturally fermented ogi and the impact of the varying microbial populations on the fate of these compounds during fermentation. In the grains, the average starch and NSP contents in each case were 80.35 g/100g and 9.40g/100g in maize and 93.12 g/100g and 8.14 g/100g in sorghum. Out of the total in grain the average percentage recovery of starch and NSP respectively in the ogi showed 63% and 42% in maize and 58% and 27% in sorghum. Maize showed good starch and fibre (NSP) retention than sorghum after fermentation. To further understand the types and levels of polymers in NSP hydrolysis in ogi fermentation, HPLC analysis of the hydrolysed extract was performed. Glucose was entirely present in maize and sorghum ogi which represents the beta-D-glucans while arabinose and xylose (in maize only), mostly lost with the pomace, signify the arabinoxylans. Overall variations in the microbial populations of sorghum seemed causal to the difference in starch and NSP recoveries. Phytate was assessed based on release of total phosphorus in the samples by enzymatic and chemical methods. Recovery of phytate in the naturally fermented ogi ranged from 18-25% in maize and 40-48% in sorghum suggesting greater phytase activity and more nutrient bioavailability in maize ogi than in the sorghum. Greater activity in maize reflects the presence of phytate hydrolysing species such as Aspergillus in the grain. Total phenolic content (TPC) was assessed by Folin-Ciocalteu colorimetric method after direct extraction of samples by saponification. TPC in the original grains ranged from 410–437 mg GAE/100g in maize and 221–247 mg GAE/100g in sorghum. Due to the nutritional significance, the amount of phenolics that are either freely soluble or are covalently bound to the food matrix were assessed. Soluble phenolics in ogi ranged from 16-38% in maize and 32-49% in sorghum based on the total soluble fraction in the original grain. In all cases loss of soluble phenolics with the waste waters accounted for 12-25% and 31-39% with the pomace. Only the LAB population seemed to correlate with the release of phenolics in the natural fermentation. Given the higher value of soluble phenolics, naturally fermented sorghum ogi appeared to have higher antioxidant potential than the maize ogi. Furthermore an attempt was made to ascertain whether the use of selected microbes would improve the antioxidant properties and aroma of ogi while minimizing the incidence of pathogens due to chance inoculation. Thus the impact of selected LAB (Pediococcus pentosaceus) and fungi (T. hirsuta and A. zeae previously shown to have phytase activity) on changes in phytate, phenolics and aroma of ogi was assessed following a parallel experiment to the previous study but using autoclaved grains. Five fermentation treatments of the pure and co-cultures were investigated. Cell populations in all culture fermentations varied and reached the average maximum of log 6-9 cfu/ml. Changes in the distribution of bound and soluble phenolics were observed showing esterase activity. Leaching of phenolics was evident in all cases but was higher in the sorghum fermentations. Higher levels of soluble phenolics were recovered in pure culture fermented ogi using T. hirsuta or P. pentosaceus than in the natural fermentation having 76% and 45% of the original soluble fraction in maize and sorghum respectively. This suggests greater antioxidant potentials than the naturally fermented ogi. Pure culture fermentations using T. hirsuta and co-culture of P. pentosaceus with A. zeae reduced phytate by 97% and 96% in maize and sorghum ogi respectively showing greater phytase activity and more nutrient bioavailabilty in the ogi than in the natural fermentation. The aroma profile of ogi was analysed by solid-phase microextraction and gas chromatography-mass spectrophotometry (SPME GC-MS). Ethyl acetate, butyl acetate and ethyl hexanoate were observed as the key active aroma components in ogi. The ester, methyl thiobutanoate was found to be unique to the naturally fermented ogi suggesting that it may have been generated by species other than the selected starter organisms. Overall in both natural and starter culture fermentations, maize ogi showed high relative abundance of volatile components suggesting good substrate compatibility and utilization during fermentation. Thus compounds with high threshold values may be significant in the aroma notes of maize ogi. P. pentosaceus and T. hirsuta in pure and in co-culture fermentations produced ogi with aroma notes mostly related to the naturally fermented product. In conclusion the diversity and levels of the initial microflora and the structural composition of grain could be major factors contributing to the nutritional compositional changes in ogi fermentation.

京都大学
0048
新制・課程博士
博士(農学)
甲第22849号
農博第2432号
新制||農||1082(附属図書館)
学位論文||R2||N5309(農学部図書室)
京都大学大学院農学研究科応用生物科学専攻
(主査)教授 佐藤 健司, 教授 澤山 茂樹, 教授 菅原 達也
学位規則第4条第1項該当
Doctor of Agricultural Science
Kyoto University
DGAM

Fermentering av livsmedel är något som människan gjort sedan de första mänskliga civilisationerna. Dessa uråldriga metoder används än idag och fermenterade drycker har under senare årtionden fått en ökad acceptans världen över och anses idag vara en trend. Syftet är att studera studenters attityder till fermenterade drycker med låg eller ingen alkoholhalt, med fokus på kännedomen om denna typ av drycker, varför och när dessa konsumeras, samt vid vilka sammanhang/tillfällen. I studien har en kortare inledande enkät distribuerats till studenter vid Högskolan Kristianstad, vilken följts av individuella, semistrukturerade intervjuer. Resultaten visade på stora skillnader i huruvida studenterna kände till och hade provat fermenterade drycker. Studenternas attityder till fermenterade drycker präglades av flera olika faktorer, exempelvis hens egna värderingar, normer och målsättningar. I enkäten visade det sig att många konsumerade fermenterade drycker för dess hälsofrämjande effekter, som ersättning till alkohol och för att testa något nytt. Detta framkom även i intervjuerna där hälsa och miljömedvetenhet var viktiga anledningar till varför fermenterade drycker konsumerades, men också nyfikenhet inför det nya. Resultaten från både enkäten och intervjuerna visade att denna typ av drycker främst konsumerades vid måltider, fester eller vid andra sociala event. Samtliga informanter var ense om att fermenterade drycker erhåller komplexa egenskaper och kanske är det just dessa karaktärsdrag som gör dryckens stora platstagande möjligt. Utifrån denna studie kan det dras en slutsats om att fermenterade drycker fyller flera roller inom kategorin låg eller icke alkoholhaltiga drycker.
Fermentation is a process that mankind has used since the first civilizations. These ancient methods are still being used today and fermented beverages has since the last few decades gained an acceptance over the world and is considered a trend. The aim of this study was to study students’ attitudes toward fermented beverages with low or no alcoholic contents, with a focus on the knowledge about these beverages, why and when they are consumed and also in what context. The study consisted of an initial shorter questionnaire which was distributed to students at the Kristianstad University, Sweden followed by an individual semi-structured interview. The results showed great variations regarding the students’ knowledge of fermented beverages and if they had tried any of these. The students’ attitudes were characterized by values and norms and the results from the questionnaire showed that many individuals consumed fermented beverages for its health-promoting effects. Instead of drinking alcoholic beverages and also to try something new. This also emerged from the interviews where health and environmental awareness were important reasons as to why fermented beverages were consumed, but also curiosity over trying something new. The results from both the questionnaire and the interviews showed that these beverages were consumed at dinner, parties or other social gatherings. All informants agreed that fermented beverages derive complex attributes and that maybe it might be these attributes that makes it possible for these beverages to take on a large audience as they do today. From this study a conclus

La sicurezza e la qualità degli alimenti sono tutt’ora un problema critico per i paesi in via di sviluppo. Le diete a basso contenuto di acido folico, per esempio, possono causare gravi problemi di salute, soprattutto nei bambini. Gravi disturbi legati al tubo neurale (DTN) nei neonati possono derivare infatti da madri che hanno insufficiente apporto di acido folico (400-600 g / giorno) durante il periodo di gravidanza. Inoltre, se non adeguatamente protetti o trattati, I prodotti alimentari possono essere vettori di funghi e batteri patogeni rappresentando una fonte potenziale di malattie per l’uomo e una perdita economica per le industrie agro-alimentari. Nella seguente tesi si è quindi quindi studiato il ruolo di batteri lattici selezionati (LAB) in grado di aumentare il valore nutrizionale del latte attraverso la produzione di acido folico durante il processo di fermentazione. Inoltre, ci si è concentrati sul loro uso come "bio-conservanti" contro funghi e batteri, attraverso la sintesi di composti antimicrobici (batteriocine) in grado di inibire la crescita di funghi filamentosi e/o batteri patogeni.
The safety and quality of food are still a critical issue in developing countries. Diets with a low content of folic acid, for example, may cause serious health problems, especially in children. Severe disorders related to neural tube (NTD) in infants may arise from mothers having inadequate intakes of folic acid (400-600 g/dia) during the mother pregnancy period. Moreover foods, when not properly protected or treated, can be vectors of pathogenic fungi and bacteria thereby representing a potential source of human diseases and an economical loss for the food industry. In the following thesis we have therefore investigated the role of selected lactic acid bacteria (LAB) in increasing the nutritional value of milk through the production of folic acid during the fermentation process. In addition, we focused on their use as “bio-preservatives” against fungal and bacterial spoilage, through the synthesis of antimicrobial compounds (bacteriocins) able to inhibit the growth of filamentous fungi and /or pathogenic bacteria.

La sicurezza e la qualità degli alimenti sono tutt’ora un problema critico per i paesi in via di sviluppo. Le diete a basso contenuto di acido folico, per esempio, possono causare gravi problemi di salute, soprattutto nei bambini. Gravi disturbi legati al tubo neurale (DTN) nei neonati possono derivare infatti da madri che hanno insufficiente apporto di acido folico (400-600 g / giorno) durante il periodo di gravidanza. Inoltre, se non adeguatamente protetti o trattati, I prodotti alimentari possono essere vettori di funghi e batteri patogeni rappresentando una fonte potenziale di malattie per l’uomo e una perdita economica per le industrie agro-alimentari. Nella seguente tesi si è quindi quindi studiato il ruolo di batteri lattici selezionati (LAB) in grado di aumentare il valore nutrizionale del latte attraverso la produzione di acido folico durante il processo di fermentazione. Inoltre, ci si è concentrati sul loro uso come "bio-conservanti" contro funghi e batteri, attraverso la sintesi di composti antimicrobici (batteriocine) in grado di inibire la crescita di funghi filamentosi e/o batteri patogeni.
The safety and quality of food are still a critical issue in developing countries. Diets with a low content of folic acid, for example, may cause serious health problems, especially in children. Severe disorders related to neural tube (NTD) in infants may arise from mothers having inadequate intakes of folic acid (400-600 g/dia) during the mother pregnancy period. Moreover foods, when not properly protected or treated, can be vectors of pathogenic fungi and bacteria thereby representing a potential source of human diseases and an economical loss for the food industry. In the following thesis we have therefore investigated the role of selected lactic acid bacteria (LAB) in increasing the nutritional value of milk through the production of folic acid during the fermentation process. In addition, we focused on their use as “bio-preservatives” against fungal and bacterial spoilage, through the synthesis of antimicrobial compounds (bacteriocins) able to inhibit the growth of filamentous fungi and /or pathogenic bacteria.

1-4% of pulse fractions including pea protein and fiber, chickpea and lentil flour as well as soy flour and protein concentrate were selected and characterized. As preliminary results the functional properties of pulse ingredients are varied upon their protein content and pH of the food carrier. Orange juice, apple juice, yogurt and two probiotic fermented milk were selected for supplementation. 1% and 2% pulse fractions gave comparable results in terms of turbidity, cloud and visual stability, color and sensory attributes for both orange and apple juices beverages. All supplements improved the acidification rate of yogurt and probiotic cultures, but the highest effects were obtained with probiotic supplementation with lentil and soy flour. As for the main study, skim milk (9.5 % w/v solid content) was supplemented with 1-3% (w/v) lentil flour, pea flour or skim milk powder and they were inoculated with yogurt starter cultures or probiotic (L. rhamnosus). Acid production during the fermentation, the pH, syneresis, color, rheological properties (dynamic oscillation temperature sweep test at 4-50 ˚C), and sensory properties (only for yogurt) were studied after production and 28 days of refrigerated storage.1-3% lentil and pea flour enhanced acid production during yogurt fermentation, but the microbial population (CFU) of both S. thermophilus and L. bulgaricus were in the same range in all lentil and pea flour and skim milk supplemented yogurts, after production. Pea flour supplementation enhanced survival of L. bulgaricus after storage. The pH decreased from 4.5 to 4.1 in lentil flour and from 4.5 to 3.75 in pea flour supplemented yogurts, after 28 days. Syneresis in 1-2% lentil and pea flour supplemented yogurts was higher than other samples. In lentil supplemented yogurts, "a" and "L" values did not significantly differ in all samples and remained constant after 28 days whereas, "b" value increased as a result of supplementation. Pea flour supplementation did not alter redness or greenness of yogurts, but the yellowness was significantly higher than other yogurts. Yogurt with 3% lentil and pea flour had higher storage (G΄) and loss (G˝) moduli in comparison with samples supplemented with 1-3% skim milk and the control yogurt. 1-2% lentil and pea flour supplemented yogurt showed comparable sensory properties in comparison with 1-2% skim milk supplemented and control samples.1-3% lentil and pea flour enhanced acid production during probiotic fermentation, and the CFU's of L. rhamnosus were comparable with non-supplemented control sample after production. After 28 days, the CFU`s of 2% and 3% lentil supplemented probiotic were as high as 1% skim milk supplemented sample and the CFU`s of 3% pea flour supplemented probiotic was the highest followed by 3-2% skim milk and 1-2% pea flour supplemented samples. The pH decreased from 4.50 to 3.90 for lentil flour supplemented probiotics and from 4.50 to 4.04 for pea flour supplemented probiotics, over 28 days. Syneresis in 1-3% lentil and pea flour supplemented probiotic was significantly lower than other samples. All lentil flour supplemented samples had significantly lower "L" values and higher "b" and "a" values in comparison with skim milk supplemented samples. Pea flour supplementation slightly changed the color which was not as light as skim milk supplemented samples and they showed more yellowness in final product after production and storage. Probiotic fermented milk with 1-3% lentil and pea flour showed higher G΄ and G˝ in comparison with other samples.
Des légumineuses tels que des protéines et fibres de pois, farine de pois chiche, de lentille et de soja ont été sélectionnées et caractérisés. Des résultats préliminaires ont montré que des propriétés fonctionnelles ont variés en fonction de la teneur en protéines et du pH des légumineuses employées. Du jus d'orange et de pomme, du yogourt et deux laits fermentés à l'aide de probiotiques ont été supplémentés avec les différentes légumineuses à des taux de 1 à 4%. Les supplémentations à 1 et 2% ont donné des résultats comparables en termes de turbidité, de stabilité, de couleur et d'attributs sensoriels pour les jus d'orange et de pomme. L'addition de légumineuse a permis d'avoir une acidification plus rapide dans les yaourts et les cultures probiotiques, mais le effet le plus important a été obtenu avec farine de lentilles et le soja dans les cultures probiotiques. Comme précédemment, des laits écrémés (9,5% p/v) ont été supplémentés avec 1-3% (p/v) de farine de lentilles, de pois ou de poudre de lait écrémé. Ils ont été inoculés avec des cultures de yogourt, des probiotiques (L.rhamnosus). La production d'acide lors de la fermentation, le pH, la synérèse, la couleur, les propriétés rhéologiques (essai dynamique balayer oscillation de température à 40-50˚C), et les propriétés sensorielles (uniquement pour les yogourts) ont été étudiés après la production et durant 28 jours d'entreposage frigorifique. 1-3% de farine de lentilles ou de pois ont amélioré la production d'acide pendant la fermentation du yogourt, mais les UFC ont les même compte pour les laits suppléments que pour les témoins (lait écrémé). Il est a noter que L. bulgaricus avaient un meilleur taux de survie au jour 28 avec une supplémentation en farine de pois. La diminution du pH dans les yogourts est de 4,5 à 4,1 avec la farine de lentille et de 4,5 à 3,75 avec farine de pois, après 28 jours. La synérèse pour les yogourts supplémentés à 1 et 2% avec de la farine de lentille ou de pois était supérieure d'autres échantillons. Lorsque le taux de supplémentation augmente en farine de lentille ou de pois, il n'y a pas de différence significative pour les valeurs de a alors que la valeur b a augmenté en fonction de la supplémentation.Les yogourts faits de 1 a 3 % farine de lentilles et de pois 1 3% avaient un module élastique (G') et un module visqueux (G˝) plus élevés que les échantillons supplémentés en lait écrémé et que les témoins. Les Yogourts avec 1 à 2% de farine de lentilles et de pois possèdent des propriétés sensorielles comparable a celles des yogourts faits avec 1 a 2% de lait écrémé et celles des témoins. 1-3% de farine de lentilles ou de pois dans des laits avec probiotiques ont amélioré la production d'acide pendant la fermentation, et les UFC de L rhamnosus étaient comparable a ceux des témoins (lait écrémé) après production. Après 28 jours, les UFC pour les échantillons supplémentés avec 2 et 3% de farine de lentille étaient aussi élevées que ceux supplémentés avec 1% de lait écrème et les UFC pour les échantillons supplémentés avec 3% de farine de pois étaient plus élevées que ceux de tous les autres échantillons. Durant les 28 jours de production le pH diminue dans les laits probiotiques contenant de la farine de lentille de 4,50 à 3,90 et pour ceux contenant de la farine de pois de 4,50 à 4,04. La synérèse dans laits probiotiques avec 1 à 3% de farine de lentilles ou de pois a été significativement plus faible que les autres échantillons. Tous les échantillons contenant de farine de lentilles avaient significativement une valeur de L plus bas et des valeurs de b et a plus élevés en comparaison aux échantillons supplémentés en lait écrémé. L'addition de farine de pois a entraîné une modification de couleur b.Les laits probiotiques supplémentés avec 1 a 3 % de farine de lentilles et de pois ont des valeurs de G' et G˝ supérieures aux autres échantillons.

Dissertação de Mestrado em Segurança Alimentar
Este trabalho teve como objetivo avaliar e comparar as características microbiológicas e físico-químicas de alguns enchidos portugueses, nomeadamente Chouriço da Beira Baixa, Mouro e Farinheira, nos quais o aspeto diferenciador é a utilização ou não de fórmulas de aditivos alimentares próprios para produtos cárneos. Foram realizadas análises microbiológicas e físico-químicas. As análises efetuadas foram contagens de Aeróbios totais a 30 ºC, de Enterobacteriaceae, de bolores e leveduras, medição da atmosfera protetora, determinação da cor, do pH, da aw, do teor de cloretos, do teor de nitritos, do teor de nitratos e do teor total de fósforo. Os resultados microbiológicos indicaram uma maior contagem de Aeróbios totais no grupo de enchidos em que não houve adição de aditivos e a contagem de bactérias da família Enterobactericeae foi baixa em todas as amostras. Os valores de aw e pH obtidos para ambos os grupos em estudo foram elevados. O aw foi superior a 0,90, mas o grupo de enchidos com adição de aditivos apresentou valores de aw ligeiramente superiores. O teor de cloretos e o teor de fósforo obtidos foram superiores no grupo de enchidos em que foram adicionados aditivos. O teor de nitratos e nitritos nas amostras em análise foram muito inferiores aos limites permitidos por lei.
ABSTRACT - The main objective of the present work is evaluates and compare the microbiological and physic-chemical characteristics of some Portuguese sausages, namely “Chouriço da Beira Baixa”, “Mouro” e “Farinheira” in which the differentiating aspect is the use or not of formulas of food additives suitable for meat products. Microbiological and physicochemical analyzes were performed. The analyzes were Total Aerobic at 30 ° C, Enterobacteriaceae, and molds and yeasts counts, the % O2 and CO2 was measured being determined protective atmosphere, color, pH, aw, chloride content, nitrite and nitrate content, and total phosphorus content. Microbiological results indicated a higher total Aerobic count in the group of sausages in which there was no addition of additives and the count of Enterobactericeae was low. The aw and pH values obtained for both groups were high. The aw was higher than 0,90, but group of sausages with addition of additives the aw value observed was slightly higher. The chloride and phosphorus content obtained were higher in the group of sausages in which additives were added. The levels of nitrates and nitrites were much lower than the limits allowed by law.

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A faveleira (Cnidosculus phyllacanthus Pax. et K. Hoffm.) é uma Euforbiácea que possui amêndoas com grande potencial para exploração, sendo rica em óleos e proteínas alimentares, é encontrada em todos os estados do Nordeste Brasileiro até o norte de Minas Gerais, principalmente na região do semi-árido. Objetivando a sua aplicação como uma alternativa para a alimentação humana, nesse trabalho foi estudado o uso das sementes da faveleira em formulados alimentícios (pão de forma e bebida láctea fermentada) visando melhorar suas características funcionais. As sementes da faveleira apresentaram amêndoas com peso de 55,85% do peso total da semente. As farinhas das sementes e das amêndoas apresentaram elevado conteúdo de lipídio (22,10 e 40,96%) e de proteína (26,25 e 35,52%) e depois de desengordurada, a farinha das amêndoas apresentou 56,18% de proteínas com presença de todos os aminoácidos essenciais, sendo a leucina o aminoácido essencial com maior concentração por grama de proteína (34,35 mg de aminoácido/g de proteína). O isolado protéico obtido apresentou coloração amarelo claro e inodoro, sendo 85,42% das proteínas extraídas. Quando aplicada como ingrediente em pão de forma, a farinha da faveleira e o seu isolado protéico proporcionaram um produto com maior teor de proteínas, variando entre os experimentos de 9,96 a 11,02% e de lipídios, variando de 2,36 a 5,80%, sendo dependentes da concentração da farinha das amêndoas da faveleira. Os pães elaborados não diferenciaram sensorialmente do pão padrão, isto indica que o produto não variou o seu aspecto gera. As sementes da faveleira foram maceradas em diferentes condições a fim de se obter o extrato solúvel e o experimento que obteve maior absorção de água pelas sementes foi com solução de bicarbonato de sódio a 0,5% a temperatura de 60ºC, uma vez que no final de 6 horas de maceração, as sementes passaram de 6,30 para 33,85% de umidade. O extrato apresentou 2,61% de proteínas, 2,01% de lipídios e pH de 6,23. A bebida láctea enriquecida com o extrato solúvel das sementes da faveleira apresentou visualmente coloração branco-amarelada, com textura e odor característicos deste tipo de produto, porém sobressaindo um aroma amendoado. Em 6 horas de fermentação a formulação com 20% do extrato da faveleira e 7,5% de inóculo contendo os micro-organismos Streptococcus termophilus e Lactobacillus delbruekii bulgaricus observou-se acidez de 74,67 °D, pH de 4,31 e 0,11 g de biomassa. A bebida láctea elaborada teve teor de umidade de 82,77%, 0,65% de cinzas, 0,01% de lipídios diferindo estatisticamente da bebida láctea padrão com 84,15% de umidade, 0,50% de cinzas e 1,74% de lipídios. Na bebida láctea adicionada do extrato das sementes da faveleira obtém-se melhor produto visual, melhor plasticidade, homogeneidade, textura, com formulação base de menor custo, melhor qualidade nutricional e ainda sem a adição de aditivo. As sementes da faveleira apresentam potencial para uso em formulados alimentícios, melhorando a sua qualidade nutricional e obtendo-se produtos com alegação funcional.
The “faveleira” (Cnidosculus phyllacanthus Pax. et K. Hoffm.) is a Euforbiácea that has almond like a food oils and proteins potencial exploration and it’s found in all the states of Brazilian Northeast even in the North of Minas Gerais, mainly in semi-arido regions. Having like a point of its application as a alternative to the human alimentation, in this paper has been studied its use in food formulation. (bread bun dairy fermented) with the point to improve its functional characteristics. The seeds of “faveleira” presented almond with weight of 55.85% of seed’s total weight. The almond float presented high content of lipids (22.10 to 40.96%) and of protein (26.5 to 35.52%), after defatted, the float presented 56.18% of proteins with the presence of all the essential aminoacids, being the leucin the essential aminoacid with the highest concentration per gram of protein (34.35 mg of aminoacids /g of protein). The protein isolated obtained presented 85.42% of soluble proteins with yellow color and odorless . When applied as ingredient on bread bun, the float of “faveleira” and its protein isolated gave into the product higher of protein and lipids quantity without differentiate sensorialy of the bread standard on the seven experiments analyzed. The seeds of “faveleira” were macerated in different conditions with the objective to obtain the soluble extract and the experiment that had higher water absorption through the seeds was the one with sodium bicarbonate 0.5% on the temperature of 60ºC, because about 6 hours of maceration, the seeds passed of 6.30 to 33.85% of humid. The extract presented presented 2.61% of proteins, 2.01% of lipids on pH of 6.23. A dairy fermented added with the soluble extract of seeds of “faveleira” presented visually coloration white-yellowed, with characteristic texture and smell sort of this product, however protruding an almonded flavor. About 6 hours of fermentation the formulation with 20% of the extract of “faveleira” and 7.5% of inoculus containing the microorganisms Streptococcus termophilus and Lactobacillus delbruekii bulgaricus presented acidity of 74.67 ºD, pH of 4.31 and 0.11g of biomass. The dairy fermented elaborated presented quantity of humid of 82.77%, 0.65% of grays, 0.01% of lipids differing statistically of the standard dairy fermented that presented 84.15% of humid, 0.50% of grays and 1.74% of lipids. In the dairy fermented added in the extract of seeds of “faveleira” the result’s a better visual product, better plasticity, homogenization, texture and with base formulation in low costs and better nutritional quality and even without no addictive addiction. The seeds of faveleira have potential for use in formulated food, improving the nutritional quality and obtaining products with functional claimming.

Bifidobacterium spp. são microrganismos probióticos que podem ser incorporados em produtos alimentícios. Entretanto, para que seus efeitos benéficos à saúde humana ocorram, é necessário que o número de células viáveis na hora do consumo seja, no mínimo, 106UFC/g. As bifidobactérias são sensíveis à elevada acidez e, por isso, torna-se necessária a busca por métodos que possam proteger a integridade da célula, sendo um deles a microencapsulação. Em uma primeira etapa do trabalho, Bifidobacterium lactis foi encapsulado em micropartículas de alginato e alginato modificado (alginatoquitosana, alginato-quitosana-sureteric e alginato-quitosana-acryl-eze) e sua sobrevivência e liberação das micropartículas em fluidos simulados do trato gastrintestinal foram mensuradas utilizando-se soluções tampão com pH 1,5, 5,6 e 7,5, na presença e na ausência de pepsina (3g/L), pancreatina (1g/L) e bile (10g/L). A liberação de células das micropartículas teve uma relação direta com o pH do tampão. A microencapsulação aumentou a taxa de sobrevivência de B. lactis, em comparação com células não encapsuladas, em soluções tampão com pH 1,5 sem a presença de enzimas. Em suco gástrico simulado com enzimas digestivas, por outro lado, foi observado que a pepsina proporcionou um efeito protetor sobre as células de B. lactis, e nesse caso, as taxas de sobrevivência do microrganismo estavam diretamente relacionadas com o grau de injúria das células. Em uma segunda etapa do trabalho, leites fermentados com Streptococcus salivarius ssp. thermophilus e Lactobacillus delbrueckii ssp. bulgaricus foram enriquecidos com culturas de Bifidobacterium lactis submetidas a quatro tratamentos diferentes: desidratação em temperatura ambiente, liofilização/congelamento, encapsulação em alginatoquitosana e encapsulação em alginato-quitosana-acryl-eze. A população sobrevivente de B. lactis foi determinada semanalmente no leite fermentado e também após tratamento simulando condições do trato gastrintestinal. Os resultados indicaram que na ausência de pepsina, as populações de B. lactis foram reduzidas drasticamente após o contato com tampão pH 1,5, não sendo possível a detecção de células viáveis livres ou encapsuladas após 120 minutos de teste. A presença de pepsina influenciou positivamente a recuperação de células viáveis de B. lactis em todas as condições testadas, mas as culturas na forma desidratada apresentaram melhores resultados que as culturas microencapsuladas ou liofilizadas. No caso do leite fermentado contendo as células desidratadas, a população de B. lactis, após o tratamento em suco gástrico com enzimas, foi superior à detectada no produto antes desse tratamento. Conclui-se que a microencapsulação não foi eficiente para proteger B. lactis em leite fermentado contra injúrias causadas pelo trato gastrintestinal simulado.
Bifidobacterium spp. are microorganisms that can be added to foods. However, the benefits for the human health occur when the numbers of viable cells in the moment of the consumption is at least 106CFU/g. Bifidobacteria are acid sensitive, and methods to protect cell integrity, such as microencapsulation, are needed. In the first part of the present study, Bifidobacterium lactis was encapsulated in microparticles of alginate and modified alginate (alginate-chitosan, alginate-chitosan-sureteric and alginate-chitosan-acryl-eze) and the survival and release from microparticles in simulated gastrointestinal conditions were measured, using buffers (pH 1.5, 5.6 and 7.5), in the absence and presence of pepsin (3g/L), pancreatin (1g/L) and bile. The release from microparticles presented a direct relationship with pH. When the pH was 1.5 and no enzyme was present, encapsulation improved the survival of B. lactis, when compared to free cells. However, pepsin had a protective effect on B. lactis, and the survival rate was directly related to the cells injury degree. In the second part of the study, fermented milk samples containing Streptococcus salivarius ssp. thermophilus and Lactobacillus delbrueckii ssp. Bulgaricus were supplemented with B. lactis submitted to four different treatments: dehydration at room temperature, freeze drying, encapsulation in alginate-chitosan and encapsulation in alginate-chitosaacryl-eze. The number of viable B. lactis cells in the fermented milk was determined weekly and also after treatment with simulated gastrointestinal conditions. Results indicated that in the absence of pepsin, the number of viable cells decreased significantly after contact with buffers (pH 1.5), and no viable cell was detected after 120 minutes. Pepsin improved the recovery of viable cells in the assayed gastric conditions, being the dehydrated cultures more resistant than other cultures. In fermented milk containing the dehydrated cells, the number of viable cells increased after treatment with simulated gastrointestinal fluids. Microencapsulation was not an effective procedure to protect B. lactis in fermented milk against injury caused by the simulated gastrointestinal tract.

Bakgrund: Med industrialiseringen har de traditionella yoghurtkulturerna med en mångfald av samverkande mjölksyrabakterier fått ge plats åt de mer standardiserade. En gårdskultur framställs genom att obehandlad mjölk spontanfermenteras av gårdens egen bakterieflora och får därigenom en unik karaktär. Bakteriekulturen kan sedan ympas vidare för tillverkning av yoghurt.Syfte: Syftet med studien är framställning och vidareympning samt sensorisk och mikrobiologisk karaktärisering av termofil gårdskultur från obehandlad mjölk. Vidareympningen avser framställning av yoghurt fermenterad av gårdens egen bakterieflora.Metod: Gårdskulturen framställdes och ympades till yoghurt. Yoghurten undersöktes genom mikrobiologisk karaktärisering, antibiotikaresistens och sensorisk profilering samt jämfördes med industriell kultur och en traditionell heirloomkultur.Resultat: Resultatet visade att gårdskulturen skiljde sig både mikrobiologisk och sensoriskt. Gårdskulturen innehöll stammar av enterokocker vilka inte visade på resistens mot analyserade antibiotika.Slutsats: Det är möjligt att framställa en gårdskultur av godtagbar mikrobiologisk och sensorisk kvalitet. Gårdskulturen ger en differentierad mikrobiologisk och sensorisk karaktär i jämförelse med en industriell kultur och en traditionell heirloomkultur Metoden kan vara riskfylld och kulturen bör analyseras med avseende på patogen tillväxt. En unik gårdsyoghurt kan vara en metod för gårdsmejerister att i sitt varumärke bygga på terroir och platsens unicitet.
Background: With industrialization, the traditional yoghurt cultures with a multitude of lactic acid bacteria had to make way for the more standardized. An artisanal farm culture is produced by raw milk spontaneously fermented by the farm's own bacterial flora and thus develops a unique character. The bacterial culture can then be inoculated for the production of yoghurt.Purpose: The pupose of the study is to produce and inoculate as well as sensory and microbiological characterization of a thermophilic artisanal farm culture from raw milk. The inoculation relates to the production of yoghurt fermented by the farm's own bacterial flora.Method: The artisanal farm culture was produced and inoculated into yoghurt which was assessed by microbiological characterization, antibiotic resistance, sensory profiling and then compared with industrial culture and a traditional heirloom culture.Result: The result showed that the artisanal farm culture differed both microbiologically and with regard to sensory paramters. The farm culture contained strains of enterococci which did not show resistance to analyzed antibiotics.Conclusion: It is possible to produce an artisanal farm culture of good microbiological and sensory quality. The artisanal farm culture provides a differentiated microbiological and sensory character in comparison to an industrial culture and a traditional heirloom culture The method may be risky and the culture should be analyzed for pathogens. A unique farm yoghurt can be a method for artisan farm dairies to build their brand based on terroir.

Thesis (MSc Food Sc )--Stellenbosch University, 2000.
ENGLISH ABSTRACT: The rapid urbanisation of the African population has led to the establishment of large low-income communities in and around almost every major town and city in South Africa. Several factors prevent these people from producing or obtaining their traditional fermented milk drink, Maas (Amasi), often resulting in the occurrence of malnutrition in low-income urban African communities. A product with the potential to satisfy the demand for a fermented milk product is Kefir. Kefir, a self-carbonated fermented milk, is commonly manufactured by fermenting unpasteurised or pasteurised milk with re-usable Kefir grains. These Kefir grains consist of a combination of mainly lactic acid bacteria and yeasts. Neither Kefir, nor Kefir grains are as yet marketed in South Africa, thus creating an excellent opportunity to launch these products locally. It is often difficult for the low-income communities to obtain high quality unpasteurised or pasteurised milk, resulting in a serious health risk. The inhibitory activity of Kefir towards certain spoilage and pathogenic microorganisms was, therefore, studied. Strains of Escherichia coli, Staphylococcus aureus, Bacillus cereus, Usteria monocytogenes and Clostridium tyrobutyricum were inoculated (10 ³ - 10 ⁴ cfu.ml⁻¹ ) into pasteurised milk together with Kefir grains (18 gram per litre) and incubated at 25°C. Uninoculated milk samples and milk samples inoculated only with test organisms served as controls. Growth of all the test organisms were inhibited substantially (>-99.9%) in Kefir over the 30 h incubation period and substantial reductions in microbial log cycles were observed for many of the organisms. This coincided with a steep decrease in pH (6.57 - 4.06) and increase in titratabie acidity (0.20 - 0.72%). If Kefir is eventually marketed to low-income urban African consumers, it will have to compete with Maas and, therefore, comparative sensory testing of Kefir and Maas was conducted. The differences in the sensory properties of Kefir, 'laboratory' Maas (representing traditional Maas) and commercial Maas (containing thickener, colourants and flavourants) were determined by a trained panel. These characteristics were identified as "yeasty" and "cowy" tastes (p < 0.05), "effervescence" (p < 0.01), as well as "sourness," "creaminess" and "smoothness" (p < 0.001). The effect of different incubation temperatures (25°, 30° and 35°C) on the Kefir sensory properties was studied to simulate the effect of the large temperature variations that would be found in the dwellings of low-income African urbanites. The "sourness" and "creaminess" of the Kefir was found to increase with increase in incubation temperature but no strong off-flavours were found to develop. Sensory preference testing was conducted by consumer panels consisting of panellists of different ages and population groups to indicate whether the specific panels significantly prefer Kefir, commercial Maas or laboratory Maas. It was found that commercial Maas was significantly (p < 0.001) preferred to Kefir by young African urbanites. Adult Africans, who presumably still have traditional taste preferences, however, equally (p > 0.05) preferred Kefir and laboratory Maas, identifying this segment of the African population as the appropriate starting target market for Kefir. Kefir and laboratory Maas were also tested for preference by a wider panel consisting of people (aged between 18 and 25) representing the different population groups in South Africa. Kefir and laboratory Maas were preferred equally (p > 0.05) by all the groups. Several arguments supporting Kefir marketing to the low-income urban African population of South Africa have been identified. These include: Kefir's ease of preparation; the re-usability of Kefir grains and subsequent affordability; good packaging, distribution and storage possibilities; Kefir's acceptability by lactoseintolerant individuals; high nutritional value; the inhibitory activity of Kefir against potential spoilage and pathogenic organisms and subsequent enhanced safety and keeping ability; and Kefir's acceptable refreshing taste.
AFRIKAANSE OPSOMMING: Die toenemende verstedeliking van Swart Suid-Afrikaners het gelei tot die vestiging van groot lae-inkomste gemeenskappe in en om die meeste groot dorpe en stede. Verskeie faktore verhoed dat hierdie gemeenskappe hul tradisionele gefermenteerde melk, naamlik Maas (Amasi), self kan maak of koop. Dit lei dikwels tot wanvoeding onder lae-inkomste stedelike Swart verbruikers. Kefir het die potensiaal om te voorsien in die vraag na 'n gefermenteerde melk produk in lae inkomste stedelike Swart gemeenskappe. Kefir is 'n selfgekarboneerde, gefermenteerde melk wat vervaarding word deur die fermentasie van ongepasteuriseerde of gepasteuriseerde melk met herbruikbare Kefirkorrels. Hierdie Kefirkorrels bestaan uit 'n kombinasie van hoofsaaklik melksuurbakterieë en giste. Kefir en Kefirkorrels word glad nie in Suid-Afrika bemark nie, en bied 'n fantastiese geleentheid om hierdie produkte plaaslik bekend te stel. Dit is dikwels moeilik om hoë kwaliteit ongepasteuriseerde of gepasteuriseerde melk in lae-inkomste gemeenskappe te verkry. Die risiko om siektes deur die verbruik van hierdie melk op te doen, bestaan dus. Om hierdie rede is die inhiberende effek van Kefir teenoor spesifieke bederf- en patogeniese bakterieë bestudeer. Rasse van Escherichia coli, Staphylococcus aureus, Bacillus cereus, Usteria monocytogenes en Clostridium tyrobutyricum is geïnokuleer (10 ³ - 10 ⁴ cfu.ml⁻¹) in gepasteuriseerde melk tesame met Kefirkorrels (18 gram per liter) en geïnkubeer by 25°C. Melkmonsters wat slegs geïnokuleer is met die toetsorganismes het as kontroles gedien. Die groei van al die toetsorganismes is substansieël geïnhibeer (>-99.9%) in Kefir gedurende die 30 h inkubasieperiode. Substansiële afnames in logsiklusgetalle is waargeneem vir baie van die organismes. Dit het gepaard gegaan met 'n skerp afname in pH (6.57 - 4.06) en toename in titreerbare suurheid (0.20 - 0.72%) vir die Kefirmonsters gedurende die 30 h inkubasieperiode. lndien Kefir bemark word aan lae-inkomste stedelike Swart verbruikers sal dit moet kompeteer met Maas. Vergelykende sensoriese toetse is dus uitgevoer. Die verskille in die sensoriese eienskappe van Kefir, 'laboratorium' Maas (verteenwoordigend van tradisionele Maas) en kommersiële Maas (wat verdikker, kleur- en geurmiddels bevat) is bepaal deur 'n opgeleide paneel en geïdentifiseer as die" "gis-" en "koeismake" (p < 0.05), die "gasserigheid" (p < 0.01) asook die "suurheid", "romerigheid" en "gladheid" (p < 0.001) van die monsters. Die effek van verskillende inkubasietemperature (25°, 30° en 35°C) op die sensoriese eienskappe van Kefir is bestudeer om die effek van die groot temperatuurvariasies wat in laeinkomste behuising mag voorkom, te simuleer. Daar is bevind dat die "suurheid" en "romerigheid" van Kefir toeneem met verhoging in inkubasietemperatuur terwyl geen afsmake ontwikkel nie. Sensoriese voorkeurtoetse is deur verbruikerspanele van verskillende ouderdomme en bevolkingsgroepe uitgevoer om te bepaal of die spesifieke panele 'n beduidende voorkeur toon vir Kefir, laboratorium Maas of kommersiële Maas. Daar is bevind dat stedelike Swart jongmense kommersiële Maas beduidend (p < 0.001) bo Kefir verkies. Swart volwassenes met verwagte tradisionele smaakvoorkeure het egter Kefir en laboratorium Maas ewe veel verkies (p > 0.05). Hierdie segment van die Swart bevolking is dus die geskikte teikenmark vir die bekendstelling van Kefir. Voorkeur vir Kefir en laboratorium Maas is ook getoets deur 'n paneel (ouderdom 18 - 25 jaar) wat bestaan uit mense van verskillende bevolkingsgroepe. AI die groepe het Kefir en Maas ewe veel verkies (p > 0.05). Verskeie argumente ten gunste van die bemarking van Kefir aan lae-inkomste stedelike Swart gemeenskappe in Suid-Afrika is geïdentifiseer. Dit behels die volgende: die gerief van Kefirvervaardiging; die herbruikbaarheid van Kefirkorrels en gevolglike bekostigbaarheid; goeie verpakkings-, verspreidings- en opbergingsmoontlikhede; Kefir se aanvaarbaarheid vir laktose-intolerante individue; Kefir se hoë voedingswaarde; die inhiberende aktiwiteit wat Kefir teenoor potensiële bederf- en patogeniese organismes het en die gevolglike verhoging in veiligheid en rakleeftyd van melk; en Kefir se aanvaarbare verfrissende smaak.

O presente trabalho tem como objetivo estudar o perfil de acidificação e a inter-relação entre Streptococcus thermophilus TAO, Lactobacillus delbrueckii subsp. bulgaricus LB340, Lactobacillus acidophilus LAC, Lactobacillus rhamnosus LBA, Bifidobacterium lactis BL04 como culturas associadas em leite fermentado. Cinco leites fermentados foram preparados, sendo a composição das co-culturas a variável estudada. O perfil de acidificação foi monitorado e os parâmetros cinéticos, calculados. Os produtos foram submetidos às análises físico-químicas e microbiológicas durante o armazenamento a 4°C. As associações em cultura mista provocaram a redução do tempo de fermentação do leite. Durante os 21 dias de armazenamento o pH e a firmeza dos leites fermentados variaram. Streptococcus thermophilus TAO, Bifidobacterium lactis BL04 e Lactobacillus rhamnosus LBA forneceram contagens acima de 106 log UFC/mL, porém Lactobacillus acidophilus LAC e Lactobacillus bulgaricus LB340 foram inibidos em cultura mista, demonstrando dificuldades de crescimento quando associados às demais bactérias ácido-láticas.
The present study aimed to evaluate the acidification kinectic and inter-relation between Streptococcus thermophilus TAO, Lactobacillus delbrueckii subsp. bulgaricus LB340, Lactobacillus acidophilus LAC, Lactobacillus rhamnosus LBA, Bifidobacterium lactis BL04 like association cultures in fermented milk. Five fermented milks were prepared and studied variable analyzed was the co-cultures composition. Acidification was monitored and the kinectic parameters were calculated. The products were submitted to physical chemistry and microbiological analyses during the storage at 4°C. The associations in mixed cultures promoted the reduction of fermentation time of the milks. During 21 days of storage, pH and firmness of fermented milks varied. Streptococcus thermophilus TAO, Bifidobacterium lactis BL04 and Lactobacillus rhamnosus LBA presented counts above 106 log cfu/mL. However, Lactobacillus acidophilus LAC and Lactobacillus bulgaricus LB340 were inhibited in mixed cultures demonstrating that these strains had difficulty to grow when in associated cultures with lactic acid bacteria.

Vietnamese soy sauce has been made for centuries using traditional methods, in villages in Northern Vietnam. This sauce differs from other Asian products not only in its raw materials but also in its flavour characteristics. Presently small scale Vietnamese soy sauce is produced mostly with a standardised inoculum of Aspergillus oryzae under natural conditions. This usually gives rise to a product of variable and inconsistent quality. The aim of this study was to standardise the fermentation condition for the production of Vietnamese soy sauce, so as to obtain a product of more consistently good quality. Aspergillus flavus var columnaris was used as the inoculum. The inoculum was prepared by growing the organism on sticky rice at 20 and 37 degrees centigrade under aerobic conditions. At 20C, a high protease activity was recorded in the inoculum while at 37C, a high amylase activity was observed. The two different inocula prepared at 20C and 37C were then used in the preparation of soy sauce in the normal manner. The inocula were mixed with cooked roasted soy beans and salt water, left to age for 1 month at 30C, followed by ageing at 20C for 2 months. The products obtained were subjected to sensory evaluation and analysed for glucose, fructose, amino acids, nitrogen, ethanol and NaCI. Both inocula produced products of acceptable quality. The inoculum produced at 20C had a higher sensory evaluation score. It also contained a higher level of protein (14.5% compared to 11%), and a higher sensory evaluation score (6.9 compared to 3.2) when compared to a commercial Vietnamese sauce, Hanoi soy sauce. This valuable information will now enable small scale producers to produce this product throughout the year by controlling the temperature, and not be limited to the summer season, as has been the case with the traditional method of production.
Master of Science (Hons)

Pubagem é o processo de fermentação natural de raízes de mandioca para produção de puba, um alimento tradicional nas regiões Norte e Nordeste do Brasil. Além da fermentação lática, uma ação combinada da pectina-metil-esterase endógena e enzimas microbianas despolimerizantes causa o amolecimento das raízes, que é importante para sua completa desintegração. No entanto, o reconhecimento do ponto final de fermentação e as condições que propiciam puba de boa qualidade não são completamente esclarecidos. O objetivo do trabalho foi estudar a influência da temperatura de fermentação e da adição de enzima como auxiliar de pubagem na textura das raízes e rendimento de puba, procurando associar estes parâmetros para detectar o ponto final desta etapa do processo. Cerca de 1Kg de raízes descascadas e 2 litros de água foram colocados em recipientes plásticos. Diferentes concentrações (0,1 e 2mL) de pectinase comercial de Aspergillus aculeatus/Kg de raiz foram adicionadas em tratamentos separados. Amostras foram incubadas a 25, 30 e 35ºC, por períodos de 48, 72 e 96 horas. Foram efetuadas análises de acompanhamento do processo fermentativo (pH, textura e rendimento) e da composição da farinha de puba obtida. O maior rendimento, de 77% após 72 horas, foi observado no tratamento a 25ºC com 2mL de enzima por Kg de raiz, quando a textura que era de 18,62lbf/g na matériaprima passou para 3,92lbf/g na raiz pubada. Outros rendimentos mais próximos desse valor, 75,7 e 74,7%, foram obtidos respectivamente na fermentação natural a 35ºC e na amostra tratada com 2mL de enzima incubada a 30ºC/48 horas. Os valores de textura foram de 2,50lbf/g para o primeiro tratamento e 2,89lbf/g para o segundo. A relação entre textura e rendimento foi significativa para a temperatura de 30ºC e todos os períodos de 72 horas. A associação entre os dados de textura e rendimento permite concluir que quando a textura alcança valores da ordem de 4lbf/g os rendimentos de puba são maiores, indicando o final do processo. Os rendimentos mais baixos ocorreram para os valores de textura próximos a 2,30lbf/g de amostra, geralmente obtidos em fermentações mais longas e com maior concentração de enzima.
"Retting" is a natural fermentation of cassava roots for the production of puba, a traditional food in the North and Northeast of Brazil. Besides the lactic fermentation, the combined action of the endogenous pectin-methyl-esterase and depolymeryzyng enzymes, causes a softening of the roots which is important for its complete disintegration. However, the recognition of the end point of fermentation and the conditions that lead to good quality puba are not completely understood. The objective of this work was to study the influence of the temperature and enzyme concentration on the yield and texture, aiming at associating these parameters to detect the end point of fermentation. The physicochemical properties of the puba flour were also determined. About 1Kg of peeled roots and 2 liters of water were placed in plastic containers. One or two milliliters of commercial pectinase from Aspergillus aculeatus were added / Kg root, in separate treatments. In the control treatment no enzyme was added. Samples were incubated at 25, 30 and 35ºC and portions removed after 48, 72 and 96 hours for the determination of pH, texture, yield and dry matter. Fibers, starch, total soluble sugars and amylose were determined in the flour of the dried puba. The highest yield of 77% was obtained after 72 hours for the treatment at 25ºC with 2mL of enzyme/kg of root, when the texture values decreased from 18.62lbf/g (raw material) to 3.92lbf/g (retted root). A high yield of 75.7% was also observed in same period, for the natural fermentation at 35ºC, when texture values of 2.50lbf/g were reached. The relation between texture and yield was significant for a temperature of 30ºC and a period of 72 hours. The association between the texture and yield data suggests that when the texture reaches values of the order of 4lbf/g, the yields are higher, indicating the end of the process. The yields were lower when texture values were close to 2.30lbf/g, usually achieved for long fermentations and higher enzyme concentrations.

The objective of this study was to evaluate the survival of non-O157:H7 STEC, Salmonella spp., and S. aureus in dry fermented sausages. Chorizo and Landjager sausages were inoculated with individual bacterial cocktails and stuffed into natural casings. Temperature, relative humidity, pH, and water activity were monitored through fermentation, drying, and storage. Bacterial counts were determined by serial dilution and plated in triplicates on selective media. Plates were incubated at 37°C for 24 hours and colony forming units per gram (CFU/g) were observed. Results of the first study validate that contaminated raw materials contribute to pathogen survival and background bacteria outcompeted the starter culture. The pH critical limit of < 5.3 was met but there was no pathogen inhibition. Results from the second study confirm that pH and water activity are not enough to eliminate pathogens when post processing interventions are not used. Critical pH (< 5.3) and water activity (< 0.85) limits were met, but pathogens still survived. In chorizo, non-O157:H7 was recovered through enrichments until the end of the study. In landjager, non-O157:H7 STEC and Salmonella were recovered through enrichments until the end of the study.The studies suggest that sausages produced without post processing interventions are a health risk to consumers.

O principal crescimento na indústria de alimentos funcionais corresponde ao dos produtos probióticos e prebióticos. A literatura mostra efeitos imunomoduladores de certas cepas probióticas, contudo, os resultados são às vezes controversos e os mecanismos implicados ainda são pouco elucidados. Sabe-se, no entanto que algumas cepas de probióticos aumentam significantemente a liberação de IL-10 e γ-INF modulando a resposta imune, além destas respostas serem de forma mais branda relacionada às bactérias Gram-positivas probióticas do que às Gram-positivas patogênicas. O presente trabalho teve como objetivo geral estudar o efeito do leite probiótico fermentado na resposta imune celular em cólon de camundongos BALB/c. Os objetivos específicos foram: (i) determinar o efeito imunomodulador do leite adicionado de probiótico em camundongos normais, (ii) identificar os tipos celulares implicados na resposta imune específica por citometria de fluxo e, (iii) colocalizá-los nos cortes histológicos. Simultaneamente, a análise e a comparação da resistência do probiótico à digestão gastrintestinal in vitro e a produção de metabólitos bioativos de acordo com os deferentes produtos foi realizada. Foram preparados leites nos quais as variáveis estudadas foram a tecnologia empregada para a produção das formulações (a) leite; (b) água, (c) leite não fermentado; (d) leite fermentado; (e) leite fermentado seguido de pasteurização, usando a mesma concentração da cepa comercial Bifidobacterium animalis subsp. lactis HOWARU HN019. O leite desnatado e a água foram usados como controles.
Functional food industry is in expansion mainly due to probiotic and prebiotic products. Studies have shown some probiotic strains develop immune modulation effect, however, these results are controversial and the mechanisms are not been well understood. Although, some probiotic strains increase IL-10 and γ-INF release modulating immune response, this response is weaker in probiotic strains when compared to pathogenic Gram-positive bacteria. The major aim of the present study was to assess the effect of probiotic fermented milk in cellular immune response of Balb/c mice colon. The specific objectives were: (i) to determine the immunomodulation of the milk added of probiotic in normal mice; (ii) to identify the cellular types implied in immune specific response and, (iii) to colocalize them in histological sections. Besides, the analyze and comparation of the probiotic resistance upon in vitro gastrointestinal and bioactive metabolites release in fermented or unfermented bifido milk using the same matrix, probiotic strain and probiotic dose in CFU. mL-1 were conducted. Dairy products were prepared in which variable form of technological appliance were: (i) milk, (ii) water, (iii) unfermented milk, (iv) fermented milk, and (v) fermented and heat treatment milk, all using Bifidobacterium subsp. lactis HOWARU HN019 strain in the same concentration. The skimmed milk and water were used as controls. The immune effects were evaluated by histological sections and the lymphocytic infiltrated was analyzed by flow citometry and histology.

Face aux pathologies de malnutrition en croissance exponentielle en particulier dans les pays du Sud, le développement d’aliments fonctionnels à base de céréales fermentées représente une alternative aux produits laitiers déjà commercialisés. L’incorporation, la stabilité de composés bioactifs liposolubles tels que les caroténoïdes et les phytostérols, ainsi que leur devenir lors de la digestion gastro-duodénale doivent être étudiés afin de démontrer le potentiel nutritionnel de ce nouvel aliment. En effet, il est connu que les phytostérols diminuent la biodisponibilité des caroténoïdes. Le principal objectif de ces travaux a été de concevoir un aliment fonctionnel probiotique à base de maïs fermenté enrichi en caroténoïdes et phytostérols, et d’étudier la stabilité, la bioaccessibilité et l’absorption intestinale de ces composés liposolubles. La formulation et la standardisation du procédé, incluant la sélection de starters de fermentation afin d’obtenir un aliment probiotique, ont été mis au point. Au cours de la fabrication, la stabilité des composés liposolubles a montré un taux de rétention de 73 %. L’effet des phytostérols dispersibles sur la bioaccessibilité de la β-cryptoxanthine, du β carotène et du lycopène de l’aliment fonctionnel a été évalué à l’aide d’un modèle de digestion in vitro simulant les conditions gastriques et duodénales. L’absorption intestinale des composés a également été mesurée en couplant le modèle de digestion in vitro aux cellules de type Caco-2 (TC7). L’étude a démontré que grâce à leur véhicule, les phytostérols dispersibles apportent un potentiel hypocholesterolémiant au produit, sans affecter la bioaccessibilité des carotènes. In fine, cet aliment fonctionnel a été optimisé d’un point de vue organoleptique et nutritionnel par l’utilisation de protéines sériques
Because of the exponential growth of malnutrition pathologies particularly in South countries, the development of functional foods based on fermented cereals represents an alternative to dairy products already marketed. The incorporation, the stability of lipophilic bioactive compounds such as carotenoids and phytosterols, as well as their behavior during the gastro-duodenal digestion have to be studied, in order to demonstrate the nutritional potential of this new product. Indeed, it is known that phytosterols decrease the carotenoid bioavailability. The main objective of this work was to design a probiotic functional food based on maize and enriched with carotenoids and phytosterols, and study the stability, the bioaccessibility and the intestinal absorption of these fat-soluble compounds. The formulation and the standardization of the manufacturing process, including the selection of starters for fermentation in order to obtain a probiotic product, were developed. During the production, the stability of fat-soluble compounds showed a retention level of 73%. The effect on dispersible phytosterols on the β-cryptoxanthine, β-carotene and lycopene bioaccessibilities was evaluated thanks to an in vitro digestion model mimicking the gastric and duodenal conditions. The intestinal absorption of these compounds was also estimate by crossing the in vitro digestion model with a Caco-2 cells model (TC7). The study demonstrated that thanks to their vehicles, dispersible phytosterols provide a potential cholesterol-lowering effect to this food, without affecting the carotene bioaccessibility. In fine, this functional food was optimized in terms of sensory and nutritional levels, by using whey protein isolates

A utilização de culturas de arranque poderá contribuir para a melhoria da qualidade e segurança dos enchidos. O objetivo deste trabalho foi avaliar os efeitos de diferentes culturas de arranque nas características físico-químicas, microbiológicas, reológicas e sensoriais e nos teores de aminas biogénicas de paios de porco preto, do Alentejo, e painhos da Beira Baixa, produzidos em ambiente industrial. Inocularam-se culturas puras de Staphylococcus equorum 5MSA4, S. equorum S2M7, Lactobacillus curvatus L2B2 e L. sakei CV3C2 e culturas mistas de levedura 2RB4, S. xylosus CECT7057, L. sakei CECT7056, S. equorum S2M7 e L. sakei CV3C2, com diferentes composições e concentrações de inoculação que variaram de 103 a 108 células/g de massa, sendo que para a levedura a concentração inoculada foi sempre de 106 células/g de massa. Os efeitos positivos das inoculações foram mais evidentes sobre as características gerais dos dois tipos de enchidos produzidos quando foram inoculadas culturas mistas, na concentração 108 células/g de massa, particularmente ao nível da segurança dos enchidos (redução dos teores totais de aminas biogénicas e das contagens e presença de microrganismos patogénicos). As inoculações não tiveram um efeito muito evidente sobre a cor, as características reológicas e a avaliação sensorial dos produtos, todavia, as culturas de arranque testadas não prejudicaram nenhum dos três conjuntos de parâmetros de qualidade referidos, porém, também não lhes conferiram características diferenciadoras. A cultura mista S. equorum S2M7 e L. sakei CV3C2, na concentração 108 células/g de massa, contribuiu para a segurança dos dois tipos de enchidos estudados sem depreciar a qualidade sensorial dos mesmos, mostrando aptidão para ser inoculada em fábricas, processos tecnológicos e regiões distintos. As culturas de arranque autóctones estudadas neste trabalho não apresentaram prejuízos para as características dos produtos, podendo considerar-se que a sua utilização pode contribuir para a segurança dos enchidos, sem comprometer a qualidade sensorial; Application of autochthonous microbial cultures in the production of the traditional sausages of Alentejo and Beira Baixa ABSTRACT: The use of starter cultures may contribute to the improvement of sausage quality and safety. The objective of this work was to evaluate the effects of different starter cultures on the physicochemical, microbiological, rheological and sensory characteristics and biogenic amines content of paio de porco preto, from Alentejo, and painhos from Beira Baixa, produced in industrial environments. Pure cultures of Staphylococcus equorum 5MSA4, S. equorum S2M7, Lactobacillus curvatus L2B2 and L. sakei CV3C2 and mixed cultures of yeast 2RB4, S. xylosus CECT7057, L. sakei CECT7056, S. equorum S2M7 and L. sakei CV3C2 were inoculated, with different compositions and inoculation concentrations ranging from 103 to 108 cells/g of meat batter, wherein for the yeast the inoculated concentration was always 106 cells/g of meat batter. The positive effects of the inoculations were more evident on the general characteristics of the two types of sausages produced when mixed cultures were inoculated, at a concentration of 108 cells/g meat batter, particularly for sausage safety (reduction of the total contents of biogenic amines and counts and presence of pathogenic microorganisms). Inoculations did not have a very evident effect on colour, rheological characteristics, and sensory evaluation of the products, however, the starter cultures tested did not affect any of the three sets of quality parameters mentioned, but also did not confer distinctive characteristics. The mixed culture S. equorum S2M7 and L. sakei CV3C2, at a concentration of 108 cells/g of meat batter, contributed to the safety of the two types of sausages studied without depreciating the sensory quality of the sausages, showing the aptitude to be inoculated in different manufactured units, technological processes and regions. The studied autochthonous starter cultures did not depreciate the characteristics of the products, and thus their use may contribute to sausage safety without compromising sensory quality.

A crescente busca por uma alimentação mais saudável e com valor agregado aumenta a necessidade de desenvolvimento de pesquisas que visem não só conhecer os alimentos, como também desenvolver e caracterizar novos produtos. Assim é fundamental que profissionais da área técnica que atuam em indústrias de alimentos e em institutos de pesquisa, trabalhem em conjunto com os profissionais da área da saúde, contribuindo para a prevenção de doenças e promoção da saúde da população. O objetivo geral do estudo foi elaborar e avaliar a atividade antibacteriana in loco de derivados lácteos elaborados a partir de grãos de kefir frente a microrganismos padrão de interesse em alimentos; e determinar a composição físico-química e microbiológica dos produtos. Inicialmente duas formulações de leite fermentado kefir (kefir 1 e 2) foram elaboradas, a primeira com leite pasteurizado e grãos de kefir e a segunda com leite pasteurizado, leite em pó e grãos de kefir. A composição centesimal e de minerais foi avaliada no leite utilizado como matéria-prima e nas formulações de leite fermentado, onde determinou-se também o pH e foi realizada a contagem de bactérias láticas totais. Com base na composição centesimal do kefir, foi verificada a possibilidade de atribuição de propriedade nutricional ao alimento e a conformidade em relação ao regulamento técnico de identidade e qualidade dos leites fermentados. Na sequencia, duas formulações de queijo (Q1 e Q2) e soro (S1 e S2) de kefir foram elaboradas a partir da coagulação microbiana realizada com grãos de kefir e determinada a composição centesimal e o pH. Cinco diferentes densidades populacionais de Staphylococcus aureus (ATCC 25923) e Escherichia coli (ATCC 11229) referidas no estudo como A, B, C, D e E (sendo A > B > C > D > E) foram inoculadas nas formulações de kefir, queijo e soro, sendo determinada a atividade antibacteriana in loco após 0, 24, 48 e 72 horas de confronto. Paralelamente cinco lotes de dez marcas comerciais de leite pasteurizado e leite UHT foram avaliados quanto à conformidade em relação à legislação de rotulagem e aos padrões de identidade e qualidade estabelecidos pela legislação brasileira. As formulações de kefir apresentaram atividade antibacteriana significativa frente às diferentes densidades populacionais dos patógenos em estudo após de 24 horas de exposição, não sendo observada atividade antibacteriana entre 24 e 72 horas de confronto. Kefir 1 e 2 atenderam aos parâmetros físico-químicos e microbiológicos previstos no regulamento técnico de identidade e qualidade de leites fermentados avaliados no estudo. A formulação 1 pode receber a declaração de “fonte de proteínas”, “reduzido em calorias” e “baixo teor de sódio” e a formulação 2 de “alto conteúdo de proteínas”, “baixo teor de sódio” e “alto conteúdo de zinco”. As formulações de queijo e soro de kefir também apresentaram atividade antibacteriana frente aos microrganismos alimentares testados, principalmente após 24 horas de confronto. A atividade antibacteriana foi mais intensa frente à Escherichia coli (ATCC 11229), obtendo-se atividade antibacteriana máxima após 48 e 72 horas de confronto de Q1, Q2, S1 e S2 com diferentes densidades populacionais do microrganismo testadas. As formulações do soro de kefir foram as que apresentaram maior atividade antibacteriana quando comparadas com o kefir e o queijo. Todas as marcas comerciais de leite avaliadas estavam em conformidade com a legislação brasileira de rotulagem. Uma marca de leite pasteurizado integral e três marcas de leite UHT integral não atenderam aos parâmetros mínimos de identidade e qualidade em pelo menos dois dos cinco lotes avaliados, apontando falhas no processo de beneficiamento. Mais pesquisas relacionadas à qualidade dos alimentos e aos derivados lácteos obtidos mediante o emprego de grãos de kefir são indicadas, explorando aspectos sensoriais, físico-químicos e microbiológicos destes alimentos, ampliando sua utilização em dietas.
The growing demand for a healthier and value-added food increases the need for research that aims not only to know food, but also to develop and characterize new products. So it is essential that technical professionals working in the food industry and research institutes to work together with health professionals, contributing to the prevention of disease and promotion of health. The overall objective of the study was to develop and evaluate the in loco antibacterial activity of dairy products made from kefir grains against standard foodborne; and to determine the physicochemical and microbiological characteristics of these products. Initially two formulations of kefir fermented milk (kefir 1 and 2) were prepared, the first with pasteurized milk and kefir grains and the second with pasteurized milk, powdered milk and kefir grains. The chemical and mineral composition of raw material (milk and powdered milk) and kefir products was evaluated, and were also determined the pH and the total lactic acid bacteria count. Based on the chemical composition of kefir, there was verified the possible nutritional property statements and also the compliance of the products with the standards of identity and quality for fermented milks. In sequence, two cheese formulations (Q1 and Q2) and serum (S1 and S2) of kefir were prepared from microbial coagulation made with kefir grains and determined the chemical composition and pH. Five different bacterial densities of Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 11229) referred as A, B, C, D and E (where A> B> C> D> E) were inoculated in kefir, cheese and whey formulations and determined the in loco antibacterial activity after 0, 24, 48 and 72 hours of confrontation. Five batches of ten commercial brands of pasteurized and UHT milk were evaluated according to the rules for labeling and the identity and quality standards established by the Brazilian food law. The kefir formulations showed significant antibacterial activity against different population densities after 24 hours of exposure and no antibacterial activity was observed between 24 and 72 hours of confrontation. Kefir 1 and 2 met the physicochemical and microbiological parameters established by the technical regulation of identity and quality of fermented milks. Formulation 1 fit the nutrition claims "source of protein", "low calories" and "low sodium", and kefir 2 "high protein content", "low sodium" and "high zinc content". The cheese formulations and kefir whey also showed antibacterial activity against the microorganisms, especially after 24 hours of confrontation. The antibacterial activity was more pronounced against Escherichia coli (ATCC 11229), with highest antibacterial activity after 48 and 72 hour confrontation of different population densities with Q1, Q2, S1 and S2. The kefir whey formulations showed higher antibacterial activity than kefir and cheese. All trademarks evaluated were in accordance with the Brazilian food labeling regulations. One pasteurized milk brand and three whole UHT milk brands did not meet the minimum standards of identity and quality in at least two of the five lots assessed, indicating flaws in the production process. More research related to quality of food and dairy products obtained through the use of kefir grains are indicated by exploring sensory, physicochemical and microbiological aspects of these foods, what could expand its use in diets.

CNPq
A crescente procura dos consumidores por alimentos que, além das funções básicas de nutrição, exercem efeitos benéficos à saúde, tem estimulado os pesquisadores e as indústrias alimentícias a desenvolverem produtos lácteos funcionais. Nesta classe, atenção especial tem sido dada ao desenvolvimento de iogurtes com propriedades probióticas e prebióticas, denominados de simbióticos. Inúmeros mecanismos têm sido propostos para tentar explicar os benefícios do consumo dos produtos lácteos simbióticos, dentre eles a capacidade que os micro-organismos probióticos têm de produzir ácido linoleico conjugado. O consumo deste composto tem sido associado a efeitos benéficos à saúde, como propriedades anticarcinogênicas, modulação do sistema imune, diminuição da aterosclerose, entre outros. O presente trabalho teve por objetivo geral a produção e caracterização de um iogurte simbiótico sabor banana obtido a partir dos leites de cabra e de vaca, das culturas probióticas Lactobacillus acidophilus e Bifidobacterium animalis subps lactis Bb-12 e polpa de banana verde como fonte de amido resistente. Para atingir este objetivo, as seguintes etapas foram realizadas: revisão bibliográfica sobre ácido linoleico conjugado, por serem o leite e seus derivados as principais fontes destes ácidos graxos; análise da composição centesimal e das propriedades físico-químicas do leite de vaca, do leite de cabra, da banana verde, da polpa de banana verde e dos iogurtes produzidos; verificação da viabilidade dos diferentes tratamentos de iogurte como carreadores de micro-organismo probiótico através da enumeração de Lactobacillus acidophilus e de Bifidobacterium animalis subps lactis Bb-12 durante a vida útil dos produtos (tempo 0, 15, 30 e 45 dias); quantificação dos micro-organismos Lactobacillus delbruecki subsp. bulgaricus e Streptococcus salivarius subps. thermophilus empregados como cultura iniciadora na elaboração dos iogurtes, durante a vida útil dos produtos (tempo 0, 15, 30 e 45 dias); estudo do perfil de textura (dureza, coesividade, elasticidade e gomosidade) e viscosidade aparente dos diferentes tratamentos de iogurte durante a vida útil (0, 15, 30 e 45 dias) e determinação da cor (parâmetro L* e coordenadas a* e b*) das diferentes formulações de iogurtes durante a vida útil (0, 15, 30 e 45 dias), um estudo de mercado e por fim, análise sensorial dos iogurtes elaborados. As seis formulações de iogurte atenderam às exigências da legislação vigente para as características físico-químicas, para a composição centesimal e para as contagens microbiológicas. Ainda, foram observadas diferenças significativas na composição centesimal, nas propriedades físico-químicas, nos perfis de cor e textura e na análise sensorial dos iogurtes elaborados com leite de vaca daqueles elaborados com leite de cabra.
The growing demand from consumers for foods that beyond basic nutritional functions, exert beneficial health effects has stimulated researchers and the food industry to develop functional dairy products. In this class, special attention has been given to the development of yoghurt with probiotic and prebiotic properties, called symbiotic. Numerous mechanisms have been proposed to explain the benefits of consuming dairy symbiotic products, including the ability of probiotic microorganisms on conjugated linoleic acid production. The use of this compound has been associated with beneficial health effects, such as anticarcinogenic properties, modulation of the immune system, reduction of atherosclerosis, among others. The overall aim of this study was the production and characterization of a symbiotic banana flavored yogurt obtained from cow and goat milk, probiotic cultures Lactobacillus acidophilus and Bifidobacterium animalis subsp lactis Bb-12 and green banana pulp as resistant starch source. To achieve this goal, the following steps were carried out: literature review about conjugated linoleic acid, analysis of the chemical composition and physicochemical properties of cow's milk, goat milk, green banana, green banana pulp and yoghurt produced; checking the viability of the probiotic microorganism Lactobacillus acidophilus and Bifidobacterium animalis subsp lactis Bb-12 by enumeration during the useful life of the products (time 0, 15, 30 and 45 days); quantification of the microorganisms Lactobacillus delbruecki subsp. bulgaricus and Streptococcus salivarius subps. thermophilus as starter culture employed in the preparation of yoghurt during the product lifetime (time 0, 15, 30 and 45 days); profile study of texture (hardness, cohesiveness, elasticity or gumminess) and apparent viscosity of different treatments during yogurt lifetime (0, 15, 30 and 45 days) and determining color (parameter L * and a * b * coordinates) of different formulations of yogurts during the lifetime (0, 15, 30 and 45 days), market study and finally, the sensory analysis of yoghurt prepared. The six yogurt formulations achieved the legal requirements for the physico-chemical properties, for the centesimal composition and for microbiological enumeration. Still, significant differences were observed in the centesimal composition, the physico-chemical properties, color and texture profiles and sensory analysis of yogurt made with cow’s milk from those made with goat’s milk.

La fermentazione è uno dei metodi più antichi utilizzati nella conservazione degli alimenti, caratterizzata da una conversione lenta dei composti organici mediata da microrganismi o enzimi di origine vegetale o animale. I cibi fermentati sono fortemente legati alla cultura e alla tradizione di un paese soprattutto nelle aree rurali. Il processo fermentativo migliora il valore nutrizionale degli alimenti, le caratteristiche organolettiche, l’accettabilità e l’appetibilità per i consumatori e prolunga la shelf life dei prodotti stessi. Il presente lavoro di Dottorato di Ricerca ha avuto l’obiettivo di caratterizzare il profilo chimico-fisico e sensoriale e di valutare la diversità e la dinamica microbica di prodotti fermentati tradizionali (formaggio Caciofiore della Sibilla e salame tipo Fabriano) e prodotti fermentati innovativi (bevande fermentate analcoliche sperimentali e pane prodotto con impasti acidi di tipo II). In dettaglio, per il formaggio Caciofiore della Sibilla è stato valutato l’impatto del coagulante vegetale ottenuto da Carlina acanthifolia All. subsp. acanthifolia sulla dinamica e la diversità microbica attraverso un approccio polifasico basato su tecniche cultura-indipendenti e tecniche cultura-dipendenti. Analogamente, per i salami tipo Fabriano l'impatto della concentrazione dei nitrati e dei nitriti sulla dinamica delle comunità batteriche metabolicamente attive è stato valutato mediante approccio polifasico basato sull'analisi del cDNA. Il pane prodotto su scala di laboratorio, utilizzando farine di grano tenero di tipo 2 e impasto acido di tipo II è stato analizzato da un punto di vista chimico-fisico, sensoriale e microbiologico. Infine, tre bevande sperimentali fermentate non alcoliche a base di riso rosso, grano saraceno e orzo sono state prodotte attraverso fermentazione guidata da specie selezionate di batteri lattici e caratterizzate mediante analisi microbiologiche, chimico-fisiche e sensoriali.
Fermentation is one of the oldest biotechnological approaches used in food conservation; it consists of a conversion of organic compounds by enzymes of microbial, plant or animal origin. Fermented foods are strongly linked to culture and tradition, especially in rural areas. They are characterized by improved nutritional value, organoleptic properties, acceptability and palatability for consumers as well as by an extended shelf life. The aim of this PhD research was to investigate the microbial diversity and dynamics of both traditional (Caciofiore della Sibilla cheese and Fabriano-like sausage) and innovative fermented foods (yogurt-like beverages and bread produced with type II sourdough) and to characterize these products for their physical-chemical and sensory profile. More specifically, the impact of an unexplored milk coagulant obtained from Carlina acanthifolia All. subsp. acanthifolia on the microbial dynamics and diversity of Caciofiore della Sibilla cheese was investigated by a polyphasic molecular approach based on culture-dependent and DNA-based techniques. The impact of nitrates and nitrites on the dynamics of metabolically active bacterial communities of a Fabriano-like sausage was also evaluated by cDNA analysis by using a polyphasic molecular approach. Moreover, experimental breads produced at a laboratory scale with type 2 soft wheat flours and type II sourdoughs were analysed to evaluate the microbial dynamics during leavening, as well as their physical-chemical and sensory traits. In the final part of thesis, non-alcoholic yogurt-like beverages were first produced at laboratory scale using three different cereal-based substrates (red rice, buckwheat and barley) and selected strains of lactic acid bacteria (LAB), and further subjected to microbiological, physical-chemical and sensory analyses.

Enterococcus faecium è un componente fondamentale del microbiota di diversi alimenti fermentati quali formaggi e salumi e viene spesso isolato in alto numero in alimenti pronti al consumo. É inoltre largamente utilizzato come probiotico sia per l’uomo che per gli animali. Allo stesso tempo, però, questa specie batterica rappresenta una delle cause principali di infezioni nosocomiali quali endocarditi ed infezioni al tratto urinario. Studi recenti hanno dimostato che la specie E. faecium è costituita da due sub-popolazioni principali: la prima è denominate hospital associated (HA) clade “A” ed include la maggior parte dei ceppi responsabili di infezioni umane; la seconda è chiamata community associated (CA) clade “B”, e contiene principalmente ceppi commensali dell’uomo. Analisi più approfondite hanno rivelato un ulteriore suddivisione all’interno del clade A, nel sub-clade A1 (che raggruppa la maggioranza dei ceppi clinici) e nel sub-clade A2, associato agli animali e più sporadicamente ad infezioni umane. Nel 2012, EFSA ha redatto una linea guida per la valutazione della sicurezza di E. faecium usato come probiotico per gli animali, concludendo che i cepi appartenenti all’hospital-associated clade non devono essere utilizzati in nutrizione animale. Comunque, la distinzione tra le due sub-popolazioni è stata fatta utilizzando dati ottenuti prevalentemente da isolati umani e animali e solo un numero limitato di ceppi isolati dagli alimenti è stato considerato. Obiettivo di questa tesi di dottorato è stato quello di valutare la sicurezza di E. faecium negli alimenti fermentati, considerando ceppi isolati da formaggi artigianali e prodotti carnei e utilizzando sia tecniche di genomica che analisi fisiologiche. Nessuno dei ceppi alimentari studiati è risultato parte del clade A1, ma un ceppo isolato da un salame stagionato pronto al consumo ha rivelato diversi tratti tipici dei ceppi A1, tra cui particolari IS, transposase e geni di resistenza agli antibiotici. Questi risultati, così come altri dati, sottolineano la necessità di approfondire le conoscenze circa il ruolo dei ceppi di E. faecium isolati da alimenti come fattore di rischio per la salute umana.
Enterococcus faecium is commonly found in high numbers in ready to eat foods, being a member of the bacterial communities of a variety of fermented foods, including cheese and sausages, and is widely used as human and animal probiotic. However, this bacterial species is a leading cause of nosocomial infection, mainly endocarditis and urinary tract infections. Recent studies have demonstrated that E. faecium species consists of two very distinct clades: the hospital associated (HA) clade “A”, which includes most of the strains responsible for human infections, and the community associated (CA) clade “B”, that contains primarily human commensal isolates. Deeper analysis revealed a further split within clade A into sub-clade A1 (which groups the vast majority of clinical isolates), and sub-clade A2, associated with animals and sporadic human infections. In 2012, the European Food Safety Authority has issued a guideline for the safety assessment of E. faecium used as animal probiotics, concluding the strains belonging to the hospital-associated clade should not be used in animal nutrition. However, the differentiation of the two clades has been performed using data mainly deriving from human and animal isolates, and only a limited number of strains from the food chain were considered. Aim of this doctoral thesis was to assess the safety of E. faecium in fermented food, considering strains isolated from artisanal cheese and meat products, and using both whole genome-based techniques and physiological studies. None of the food isolates studied in this work belong to the epidemic clade A1, however a strain isolated from a ready to eat salami revealed several A1-specific traits, such as specific IS, transposases and antibiotic resistance genes. These results, as well as other data, underline the emergency of deeper understanding the role of E. faecium isolated from fermented foods as risk factor for human health.