Дисертації з теми "Technologie hurdle"

L'environnement opératoire dans les domaines alimentaire et médical permet aux bactéries de se fixer et de se développer sur les surfaces, ce qui entraîne la formation de biofilms bactériens pathogènes et résistants. Ces structures pathogènes sont responsables de nombreuses maladies d'origine alimentaire et d'infections associées aux soins. Par conséquent, pour lutter contre ce fléau de santé publique, plusieurs stratégies ont récemment été proposées, notamment l'élimination chimique et mécanique. Ce travail présente les différents facteurs qui influencent l'adhésion bactérienne et la formation de biofilms sur des surfaces abiotiques, ainsi que la résistance des biofilms aux désinfectants. La microencapsulation par la méthode de séchage par pulvérisation pour la formulation de composants actifs anti-biofilm en vue d'assurer leur stabilité et améliorer leurs activités biologiques est également présentée. Dans ce contexte, une étude a été menée en utilisant le carvacrol, un agent antimicrobien naturel, pour contrôler les biofilms de Pseudomonas aeruginosa et Enterococcus faecalis. En effet, ces deux bactéries sont responsables de nombreuses infections dans le monde en raison de leur persistance sur des surfaces abiotiques dans les hôpitaux et les industries agroalimentaires. Par ailleurs, afin de renforcer l'activité antimicrobienne du carvacrol et de réduire sa volatilité et sa faible solubilité dans l'eau, des émulsions ont été préparées avec du caséinate de sodium et des maltodextrines, puis séchées par atomisation pour obtenir des microcapsules de carvacrol sèches. Les résultats ont montré que le carvacrol exerce une forte activité antimicrobienne contre les deux biofilms bactériens. De plus, nos résultats ont révélé que la microencapsulation par séchage par pulvérisation a augmenté de manière significative l'activité antimicrobienne du carvacrol tout en réduisant les quantités utilisées. En effet, le carvacrol microencapsulé a été capable de réduire le biofilm en dessous de la limite de détection pour Pseudomonas aeruginosa et de 5.5 log CFU mL-1 pour Enterococcus faecalis après 15 min de traitement. L'efficacité de la technologie hurdle pour éliminer les biofilms en utilisant différentes stratégies est discutée dans ce travail. Une des approches de la technologie hurdle est l'utilisation d'enzymes qui peuvent dégrader la matrice et disperser les bactéries intégrées dans les biofilms pour une désinfection plus efficace lorsqu'elles sont combinées avec des agents biocides. En effet, deux enzymes protéolytiques, la pepsine et la trypsine, ciblant les protéines de la matrice, ont été étudiées pour leur potentiel de dégradation des biofilms de Pseudomonas aeruginosa et Enterococcus faecalis et leur effet synergique lorsqu'elles sont combinées au carvacrol. L'analyse directe par microscopie à épifluorescence a permis de visualiser l'activité dispersive des protéases et l'activité létale du carvacrol contre les deux biofilms bactériens. En outre, le traitement combiné avec la pepsine ou la trypsine et le carvacrol a entraîné une réduction plus significative des deux biofilms par rapport au traitement avec le carvacrol seul. De plus, cette réduction était plus importante après un traitement séquentiel avec les deux enzymes suivies du carvacrol. Cependant, l'activité enzymatique est fortement influencée par les facteurs environnementaux et n'est optimale que dans des conditions restreintes. Un autre inconvénient de l'utilisation des enzymes est l'auto-dégradation, qui entraîne leur instabilité. En effet, des microcapsules de protéase contenant de la pepsine ou de la trypsine complexées avec de la pectine et de la maltodextrine ont été préparées
The ambient operating environments in the food and medical sectors allow bacteria to adhere and develop on the substrates, resulting in the growth of resistant pathogenic bacterial biofilms. These pathogenic structures are responsible for several foodborne diseases and health-care associated infections. Consequently, to combat this public health burden, several strategies have recently been proposed which include chemical and mechanical removal. This work presents the different factors that influence bacterial adhesion and biofilm formation on abiotic surfaces, as well as biofilm resistance to disinfectants. The different strategies for biofilm prevention and eradication are described. Microencapsulation using spray-drying method for the formulation of anti-biofilm active components as a tool to ensure their stability and improves their biological activities are also presented. In this context, a study was conducted using carvacrol, a natural antimicrobial agent, to control biofilms of Pseudomonas aeruginosa and Enterococcus faecalis. Indeed, these two bacteria are responsible for several infections worldwide due to their persistence on abiotic surfaces in hospitals and food processing industries. Furthermore, in order to enhance the antimicrobial activity of carvacrol and reduce its volatility and low solubility in water, feed emulsions were prepared with sodium caseinate and maltodextrins and then spray dried to obtain dry carvacrol microcapsules. The results showed that carvacrol had a strong antimicrobial activity against both bacterial biofilms. Furthermore, our findings revealed that microencapsulation by spray drying significantly increased the antimicrobial activity of carvacrol while reducing the amounts used. Indeed, microencapsulated carvacrol was able to reduce biofilm below the detection limit for Pseudomonas aeruginosa and 5.5 log CFU mL-1 for Enterococcus faecalis after 15 min of treatment. However, the complete removal of biofilms from abiotic surfaces in medical and food sectors has proven difficult with the single use of disinfection strategy due to the high protection of the biofilm cells by the extracellular polymeric matrix. This matrix provides an initial protective barrier for the biofilm cells, and makes biofilms highly resistant to antimicrobial agents. The effectiveness of hurdle technology in removing biofilms using different strategies is discussed in this work. One of the hurdle technology approaches is the use of matrix-degrading enzymes that can disperse bacteria embedded in biofilms for more efficient disinfection when combined with biocide agents. Indeed, two proteolytic enzymes, pepsin and trypsin, targeting matrix proteins, have been studied for their potential to degrade biofilms of Pseudomonas aeruginosa and Enterococcus faecalis and their synergistic effect when combined with carvacrol. The direct analysis using epifluorescence microscopy allowed visualization of the dispersive activity of proteases and the lethal activity of carvacrol against the two bacterial biofilms. In addition, the combined pepsin or trypsin treatment with carvacrol showed more significant reduction of both biofilms compared to carvacrol treatment alone. Moreover, this reduction was more substantial after sequential treatment of both enzymes followed by carvacrol. However, the enzyme activity is highly influenced by environmental factors and is only optimal under restricted conditions. Another disadvantage of using enzymes is self-degradation, leading to instability. Indeed, protease microcapsules containing pepsin or trypsin complexed with pectin and maltodextrin have been prepared

In this study, potential of high hydrostatic pressure (HHP) and essential oils (EOs) as natural antimicrobials was evaluated to produce E. coli safe and quality beef product. First, the individual and combined effects of antimicrobial activity (minimum inhibitory concentration) of basil, black cumin, cilantro, cumin, fenugreek, ginger, oregano, black pepper, rosemary, thyme, turmeric oil emulsions on E. coli ATCC 25922 with and without HHP treatment were evaluated. Cumin, oregano and thyme EOs showed highest antimicrobial activity against E. coli ATCC 25922. The synergy of selected EOs against E. coli ATCC 25922 was determined using the checkerboard method to obtain fractional inhibitory concentration index. Although their combinations did not show synergy, they expressed synergy when combined with HHP (400 MPa, 10 min, 20 °C) and the best combination was cumin and oregano EOs with HHP. Effects of HHP and EO combinations on inactivation of E. coli ATCC 25922 in beef were investigated using response surface methodology (RSM). Statistical analysis showed the model was significant for predicting log reduction with high accuracy. The significant model terms were pressure and time. Compared to control, HHP/EO treated samples showed no-post growth when stored up to 120 days at 4°C. Presented results suggests that the combination of HHP and antimicrobials has not only improved the process parameters (lowered pressure, time, and EO concentration) but also prevented recovery of E. coli ATCC 25922 during storage. RSM was employed to analyze the synergistic effects of HHP and EOs on beef quality (color, texture and lipid oxidation). Color indices were significantly affected by pressure, time and their interactions. Above 400 MPa the discoloration was similar to cooked beef and EO addition did not help color improvement. However, EOs showed significant antioxidant activity on both treated and untreated samples during storage. In conclusion, there is a great potential of HHP and EO combinations to enhance pathogen inactivation while keeping the quality of beef. Moreover, presence of EOs can prolong the shelf life of pressure treated beef. Therefore, the combination of HHP and EO is very promising for meat industry.
Ph. D.

Thesis (S.M.M.O.T.)--Massachusetts Institute of Technology, Sloan School of Management, Management of Technology Program, 2004.
Includes bibliographical references (leaves 29-34).
The nuclear winter that filled the vacuum created by the Internet implosion was characterized by highly conservative investments in new technologies. This was particularly true for Internet- and Web-oriented technologies since after all, being a believer just wasn't as popular as it used to be. However, life, business, and science go on, and the Web is no exception. This thesis will examine hurdles in the business case for the Semantic Web. In one sense, the Semantic Web is an extension or enhancement of the existing World Wide Web (Web). As we know it today, the Web is a rich medium that allows humans to express themselves, learn, interact, and reach an audience that was a pipe dream just a decade ago. At the same time, the Web is of limited utility to computers (machines). For example, a human being could easily recognize a postal address or the specifications of an order for steel; a machine could not. To a machine, these data would simply be elements to be rendered and displayed on a monitor, with no intrinsic or cumulative meaning. In this sense, one of the goals set for the Semantic Web is to create meaning and utility for machines that allows for interpretation and action with far less human intervention. Issues related to the challenges, practicalities, theories and opportunities of the Semantic Web will be discussed. In the process, hopefully, this thesis will identify some of the stepping stones in building a business case for this evolution. Notably, today's comments regarding the Semantic Web sound very similar to what was once said about the practicalities of eBusiness and the likelihood of its adoption.
by David Provost.
S.M.M.O.T.

Agile methodology has gained wide adoption. Agile methodology, with its iterative and incremental approach for software development, has gained popularity within IT organizations that are facing a dynamic business environment. Agile software development has emerged as an alternative to the traditional Waterfall model in delivering software at a faster pace and having more receptiveness towards the changing requirements. However, Agile methodology was originally designed for small and individual teams. This makes moving Agile to large-scale organizations a complicated task. In this thesis, we will review the challenges and success factors presented by (Dikert et al., 2016) in their systematic literature review for SAFe (Scaled Agile framework). Our thesis is based on empirical research. The authors have conducted interviews to gather data to underpin or dissent from the findings in the systematic literature review regarding the challenges and success factors of implementing SAFe in organizations.

Orientador: Fumio Yokoya
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Doutorado
Doutor em Ciência de Alimentos

Inledning En tredjedel av den mat som produceras i världen slängs (United Nations Development Programme [UNDP], 2020) och de livsmedelsförstörande mikroorganismerna är ett vanligt förekommande problem och en bidragande orsak till det globala matsvinnet (Snyder & Worobo, 2018). Livsmedelsindustrin använder därför olika hurdletekniker för att minimera risken för tillväxt av förskämningsorganismer (Snyder & Worobo, 2018). En strategi för att kontrollera om olika hurdletekniker uppfyller sitt syfte är att utsätta ett livsmedel för ett belastningstest. Syfte Syftet med studien var att genom ett belastningstest i ett flytande livsmedel jämföra konserveringsmedlen lingonjuice och kaliumsorbat + natriumbensoat samt att undersöka produktens fysikaliska och kemiska förändringar över tid.  Material och metod Ett flytande livsmedel (n = 73 á 180 ml) inokulerades i ett belastningstest med log 2–3 mikroorganismer per ml livsmedel. Därefter tillsattes konserveringsmedlen lingonjuice (n = 24) eller kaliumsorbat + natriumbensoat (n = 25). En tredjedel av proverna (n = 24) lämnades utan konserveringsmedel. Provtagning för analys av tillväxt, färg, pH och viskositet (mPas) utfördes vid 0, 14 och 30 dagar efter livsmedlet inokulerats med mikroorganismer.   Resultat Resultatet visade mikrobiell tillväxt i samtliga livsmedel vid dag 0. Dag 14 identifierades tillväxt i livsmedlet med kaliumsorbat + natriumbensoat samt lingonjuice. Vid analysen på dag 30 identifierades tillväxt i livsmedlet med kaliumsorbat + natriumbensoat och i livsmedlet utan konserveringsmedel. Över tiden skedde även fysikaliska förändringar i viskositet och kemiska förändringar av pH-värdet. Gällande färg skedde enbart marginella förändringar. Slutsats Resultatet av belastningstestet visade att lingonjuice är det konserveringsmedel som har bäst effekt med avseende på produktstabilitet genom att hämma tillväxt av tillsatta mikroorganismer. Resultaten av de fysikaliska mätningarna visade på förändringar över tid med avseende på viskositet. Färg visade enbart minimala förändringar. Resultatet av den kemiska mätningen visade på förändringar av pH-värdet över tid.
Introduction One third of food produced in the world is discarded (United Nations Development Program [UNDP], 2020) and food-destroying microorganisms are a common problem and a contributing cause of global food waste (Snyder & Worobo, 2018). The food industry therefore uses various hurdle techniques to minimize the risk of growth of spoilage organisms (Snyder & Worobo, 2018). One strategy to check whether different hurdle techniques meet their purpose is to expose foods in a challenge test. Aim The aim of the study was to compare the preservatives lingonberry juice and potassium sorbate + sodium benzoate and examine any physical and chemical changes over time through a challenge test on a liquid food product. Material and method A liquid food (n = 73 á 180 ml) was inoculated in a challenge test with log 2-3 microorganisms per ml food. Thereafter preservatives lingonberry juice (n = 24) or potassium sorbate + sodium benzoate (n = 25) were added. One third of the samples (n = 24) were left without preservatives. Sampling for analysis of growth, color, pH and viscosity (mPas) was performed at 0, 14 and 30 days after the food was inoculated with microorganisms. Results The results showed microbiological growth in all food products at day 0. Day 14 growth were found in the food with potassium sorbate + sodium benzoate and lingonberry juice. By the analysis on day 30 growth in the food with potassium sorbate + sodium benzoate and in the food without preservatives were showed. Over time physical changes of viscosity and chemical changes of pH occurred. Regard to color only marginal changes occurred. Conclusion The result of the challenge test showed that lingonberry juice is the preservative that has the best effect regard to product stability through inhibiting the added microorganisms. The results of the physical measurements showed changes regard to viscosity over time. Color only showed marginal changes. The result of the chemical measurement showed changes of pH over time.

I campi elettrici pulsati (PEF) sono considerati una valida tecnologia non termica, anche se generalmente non possono essere considerati un metodo di sterilizzazione, ma piuttosto sostituire una pastorizzazione. Per questo motivo, necessitano di essere abbinati ad altre tecniche (blandi trattamenti termici, aggiunta di antimicrobici o acidificazione del mezzo). In questo elaborato è stato utilizzato un prototipo PEF, costruito dal gruppo di Ingegneria del Campus di Cesena ed in grado di effettuare trattamenti a 50kV/cm, per valutare l’inattivazione di un ceppo di Saccharomyces cerevisiae isolato da bevande degradate. Sono state effettuate diverse prove dove il trattamento PEF è stato combinato con diversi livelli di pH (4 e 6), aggiunta di citral a metà della MIC e preriscaldamento a 50C°. Il PEF ha dimostrato un effetto sinergico con citral e calore, mentre non sono state osservate differenze significative in relazione al pH. Mediante analisi citofluorimetrica è stato riscontrato che a pH 6 il trattamento determina in generale una maggiore mortalità cellulare, mentre a pH 4 le cellule erano per lo più danneggiate. Inoltre in questa sperimentazione è stata valutata non solo l’efficacia del trattamento PEF a diverse condizioni, ma anche l’eventuale capacità di recupero delle cellule trattate durante un periodo di incubazione di 6 ore. I dati hanno mostrato che la presenza di citral abbinato ad un preriscaldamento determina una ridotta capacità delle cellule di recuperare i danni subiti e ripristinare la loro attività metabolica. Questa sperimentazione si è quindi rivelata utile al fine di individuare le condizioni di processo e le variabili in grado di massimizzare l’efficacia del trattamento. Inoltre, l’utilizzo della citometria di flusso, ha permesso di discriminare i diversi stadi fisiologici all’interno della popolazione di lievito, ottenendo informazioni circa il meccanismo di azione del PEF, esercitato principalmente a livello della membrana cellulare.

O presente trabalho consistiu na padronização do ratio, definido como a razão entre o teor de sólidos solúveis (SS) e a acidez titulável (AT), no processamento em escala piloto e no estudo da vida de prateleira (VP) de caldo de cana estocado sob refrigeração. Utilizando-se um delineamento central composto rotacional, com onze formulações de caldo de cana, investigou-se o ratio da formulação que resultou em melhor aceitação sensorial, em uma ampla faixa de SS (13,1 a 25,9 ºBrix) e de AT (0,02 a 0,09 % de ácido cítrico). Determinada a melhor formulação, processaram-se três lotes de caldo de cana padronizado (L1, L2 e L3). A estabilização da bebida foi baseada na seguinte combinação de métodos térmicos e não térmicos: acidificação, pasteurização (95 ºC/ 30 s), envase asséptico em garrafas de polietileno tereftalato (PET) e estocagem refrigerada. Testes físico-químicos, microbiológicos e enzimáticos, incluindo-se a determinação da atividade da peroxidase (POD) e da polifenoloxidase (PPO) foram realizados na bebida in natura e recém-processada (tempo zero da VP). Para o estudo da VP do caldo de cana padronizado pasteurizado, as amostras, em todos os lotes processados, foram fracionadas e estocadas nas temperaturas de 4, 8, 12 e -18 ºC (controle), na ausência de luz. A estimativa de VP do produto foi fundamentada em testes microbiológicos e sensoriais. A avaliação da estabilidade microbiológica baseou-se na enumeração de bactérias e fungos psicrotróficos. Testes de escala hedônica de nove pontos para avaliação da aparência e do sabor foram empregados na análise da estabilidade sensorial. As médias da aceitação sensorial para impressão global das onze formulações não apresentaram diferença estatística (p > 0,05) entre si, nas faixas de SS e AT estudadas. Verificou-se que apenas o efeito da AT foi significativo (p < 0,05) na aceitação da bebida. A formulação escolhida para a padronização do caldo de cana foi aquela com AT equivalente a 0,09 % (pH próximo a 3,9) e 19,5 ºBrix. Para o caldo de cana padronizado pasteurizado recém-processado, os valores de pH foram inferiores a 4,4 em L1, L2 e L3. As contagens de mesófilos não ultrapassaram 50 UFC/ mL, constatando-se a ausência de coliformes termotolerantes e Salmonella em todos os lotes processados. As médias das atividades de POD e PPO foram de 2,11 U/mL e 1,03 U/mL, respectivamente. As contagens de bactérias e fungos psicrotróficos não ultrapassaram 102 UFC/ mL. As médias dos tempos de VP estimadas para as frações dos lotes estocadas a 4, 8 e 12 ºC foram equivalentes a 71, 74 e 23 dias, respectivamente. Concluiu-se que o caldo de cana foi bem aceito pela equipe de provadores, em uma ampla faixa de SS e AT. A combinação dos métodos empregados na estabilização da bebida foi eficiente na redução da atividade enzimática e da contagem microbiana. Além disso, as temperaturas de 4 e 8 ºC mostraram-se efetivas na manutenção da estabilidade da bebida, satisfazendo a uma eventual demanda do mercado consumidor pela bebida processada.
The present study consisted in standardizing the total soluble solids (SS) and titratable acidity (TA) ratio, in small scale processing and in estimating the shelf-life (SL) of sugarcane juice stored under ideal, commercial and abusive temperature conditions. A central composite rotational design with eleven formulations of sugarcane juice was used to investigate the ratio of the formulation that resulted in the best sensory acceptance in a wide range of SS (13,1 a 25,9 ºBrix) and TA (0,02 a 0,09% citric acid). Found the best formulation, three batches of standardized sugarcane juice were processed (L1, L2 and L3). The juice´s stabilization was based on the following combination of thermal and non-thermal methods: acidification, pasteurization (95 °C/30 s), aseptic filling in polyethylene terephthalate (PET) bottles and refrigerated storage. Physico-chemical, microbiological and enzymatic tests, including the determination of the peroxidase (POD) and polyphenol oxidase (PPO) activities, were performed in the fresh and freshly processed (time zero of SL) juice. For the SL study, standardized pasteurized sugarcane juice samples were stored at temperatures of 4, 8, 12 and -18 °C (control), kept in the dark. The estimate of the product´s SL was based on microbiological and sensory tests. The evaluation of the microbiological stability was based on the psychrotrophic bacteria and fungi counts. Nine-point hedonic scale tests for appearance and flavor evaluation were used in order to assess the sensory stability. The mean values of sensory acceptance, for overall impression, of the eleven formulations showed no statistical difference (p > 0.05) among them. It was found that only the effect of TA was significant (p < 0.05). The chosen formulation for sugarcane juice standardization was that one with TA 0.09 % (pH near 3.9) and SS 19.5 ºBrix. For the freshly processed standardized pasteurized juice, the pH was less than 4.4 in L1, L2 and L3. The mesophilic counts did not exceed 50 CFU/mL. The presence of coliforms at 45 ºC and Salmonella was no confirmed. The average POD and PPO activities were 2.11 U/mL and 1.03 U/mL respectively. The psychrotrophic bacteria and fungi counts did not exceed 102 CFU/mL. The juice´s SL stored at 4, 8 and 12 °C were 71, 74 and 21 days, respectively. It was concluded that the juice was well accepted in a wide range of SS and TA, and the combination of methods was effective in reducing the enzyme activity and microbial counts. Moreover, temperatures of 4 and 8 °C were proved to be effective in maintaining the sugarcane juice´s quality for a period of time compatible with the consumer market demand.

O caldo de cana adicionado de polpa ou suco de fruta é uma bebida bastante apreciada no Brasil. O presente trabalho consistiu na elaboração, no processamento em escala piloto e no estudo da vida de prateleira de caldo de cana com polpa de maracujá. Processaram-se nove lotes de caldo de cana adicionado de 4% (m/m) de polpa de maracujá, a 85, 90 e 95 °C/30 s, em triplicata. A bebida pasteurizada foi envasada assepticamente em garrafas de polietileno tereftalato (PET) e estocada a 7 °C, na ausência de luz. Testes físico-químicos foram empregados na caracterização da bebida. Procedeu-se à análise do teor de vitamina C no caldo in natura e na bebida processada. Determinaram-se as atividades das enzimas polifenoloxidase (PPO) e peroxidase (POD) antes e após o processamento. A estimativa da vida útil do produto foi fundamentada em testes microbiológicos e sensoriais. A avaliação da estabilidade microbiológica baseou-se na enumeração de bactérias e fungos psicrotróficos. Testes de escala hedônica de sete pontos para avaliação da aparência, aroma, sabor e aceitação global foram empregados na análise da estabilidade sensorial. As médias dos valores de pH, sólidos solúveis e acidez titulável variaram entre 3,9 e 4,0; 17 e 23 °Brix; e 0,15 e 0,19% de ácido cítrico, respectivamente. A polpa de maracujá não incrementou o teor de ácido ascórbico da bebida que ficou entre 2,6 a 2,8 mg/ 100 mL de bebida. A atividade da PPO variou entre 3,1 e 40,3 U/mL para os nove lotes do caldo acidificado, antes da pasteurização. Os três binômios empregados no processamento foram efetivos na inativação da enzima. A atividade da POD oscilou entre 69,8 e 220,4 U/mL; contudo, apenas o processamento a 95 °C atingiu 100% de inativação. As contagens de bactérias e fungos em todos os nove lotes processados foram inferiores a 2 log UFC/mL ao longo de 90 dias de estocagem. A bebida atingiu médias de notas entre 5 e 6 para todos os atributos avaliados após 30 dias de estocagem. As médias dos tempos de vida útil da bebida processada a 85, 90 e 95 °C/30 s atingiram 31, 39 e 52 dias, respectivamente. Concluiu-se que o aumento da temperatura de pasteurização afetou positivamente a estabilidade da bebida. Contudo, o decréscimo da aceitação sensorial limitou a sua vida útil, no qual o sabor foi o principal atributo limitante.
Sugarcane juice, either pure or with fruit pulp addition, is an appreciated beverage in Brazil. The aim of this research was to evaluate the shelf-life of sugarcane juice mixed with passion fruit pulp (4% w/w). Nine batches were processed at 85, 90 and 95 °C/30 s, in three replicates. The pasteurized beverage was aseptically filled into polyethylene terephthalate (PET) bottles and stored at 7 °C without light exposure. pH, soluble solids and titrable acidity were measured during storage. The content of vitamin C was analyzed both in fresh sugar cane juice and pasteurized beverage. Polyphenoloxidase (PPO) and peroxidase (POD) activities were determined both before and after processing. Microbiological stability evaluation was based on psychrotrophic bacteria and fungi counts. Sensory acceptance was estimated by assigning a liking score on a 7-point hedonic scale to the attributes appearance, flavor, taste and overall appreciation. The mean values for pH, soluble solids and titratable acidity ranged from 3.8 to 4.3, 15 to 24 °Brix, and 0.13 to 0.17% of citric acid, respectively, for all processed batches. The passion fruit pulp did not increase the ascorbic acid content in the pasteurized product which ranged from 2.6 to 2.8 mg / 100 mL of beverage. The PPO activity varied from 3.1 to 40.3 U/mL for the nine acidified sugarcane juice batches before pasteurization. The three pasteurization binomials were effective for enzyme inactivation. The POD activity ranged from 69.8 to 220.4 U/mL. However, only processing at 95 °C achieved complete inactivation. The bacteria and fungi counts in all nine pasteurized batches were lower than 2 log CFU/mL up to 90 days of storage. The product achieved scores between 5 and 6 for all sensory attributes evaluated after 30 days of storage. The estimated shelf-life for beverage processed at 85, 90 and 95 °C/30 s was 31, 39 and 52 days, respectively. It was concluded that pasteurization temperature had a positive effect on beverage stability. Nevertheless, the decrease in flavor acceptance was the main limiting factor for the product\'s shelf-life.

Tese de Doutoramento em Ciência e Tecnologia Animal
Este trabalho visou caracterizar a tecnologia tradicional de fabrico dos Maranhos, determinar as suas características físico-químicas, microbiológicas e organolépticas, identificar os factores que limitam a sua conservação e que dificultam a sua distribuição, antecipar os potenciais perigos que possam advir do seu consumo e, experimentar alterações tecnológicas capazes de melhorar e adequar o produto às exigências do mercado actual. Idealizaram-se e experimentaram-se alterações tecnológicas assentes na conjugação de diferentes barreiras físico-químicas, testando-se a acção de diferentes combinações dos aditivos nitrito de sódio (E250), ácido ascórbico (E300), sorbato de potássio (E202) e metabissulfito de sódio (E223) em Maranhos processados termicamente, embalados a vácuo e conservados a 4 ºC, recorrendo a ensaios de validade com controlo periódico dos parâmetros físico-químicos, microbiológicos e sensoriais, estabelecidos de acordo com a sua relevância para a qualidade do produto. No Lote 2 e também no Lote 4 foi possível alargar a validade do produto já cozinhado para 3 semanas, cumprindo desta forma com as exigências da moderna distribuição e melhorando inclusivamente conforme foi perceptível pela avaliação do painel de provadores, algumas das suas características organolépticas.
ABSTRACT - Traditional meat products from “Pinhal” zone : characterization and technological improvement of “Maranhos” manufacturing process - The aim of this work was to characterize the traditional manufacturing process of “Maranhos” and determinate its physical-chemical, microbiological and sensorial attributes, identify the factors that compromises its shelf-life and commercial distribution, anticipate potentials hazards due to its consumption and experiment technological changes in order to improve and add value to the product according to the present market requirements. Technological changes based on the combined action of some different physical-chemical hurdles were idealized and experimented. The impact of some different combinations of food additives, sodium nitrite (E250), ascorbic acid (E300), potassium sorbate (E202) and sodium metabisulphite (E223) were evaluated by shelf-life trials, based on regular control of some previous established physical-chemical, microbiological and sensorial attributes considered relevant to the quality of refrigerated (4ºC) vacuum packaged cooked “Maranhos”. An extension of 3 weeks at shelf-life of this cooked meat product was attained in batch 2 and also in batch 4, according to the requests of modern commercial distribution, improving also some of the product sensory attributes has it was revealed by the sensory analysis expertise’s.
Bolsa de Investigação no âmbito do POS _C - Desenvolver Competências - Medida 1.2 da Fundação para a Ciência e Tecnologia Ref. SFRH/BD/34186/2006.

Orientadores: Marcelo Cristianini, Pilar Rodriguez de Massaguer
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: O néctar de manga é apreciado por sua cor e aroma. Este produto, pela sua alta acidez, pode ser contaminado por bolores, dentre os quais são de grande relevância aqueles capazes de sobreviver ao processamento térmico. O processamento a alta pressão dinâmica (APD) é um tratamento ¿a frio¿ realizado para inativação de microrganismos visando uma melhor qualidade sensorial e nutricional do produto obtido. Neste estudo, avaliou-se o efeito do processamento a APD isoladamente ou combinado com tratamento térmico (TT) brando na inativação de Aspergillus niger em néctar de manga e, posteriormente, foi realizada a avaliação do efeito dos processos sobre a cor e a concentração de vitamina C do néctar. Paralelamente foi desenvolvida uma metodologia para limpeza e sanificação do equipamento e um processo para a redução de viscosidade do néctar de manga. Foram estudadas pressões entre 100 e 300 MPa para a inativação do Aspergillus niger. A pressão de 300 MPa inativou toda a carga inicial (> 6,24 reduções decimais), 200 MPa provocou uma inativação parcial (aproximadamente 2 ciclos) e, pressões inferiores a 150 MPa não resultaram em inativação significativa do A. niger. Quando o processo de APD foi associado à TT brando (80ºC/15minutos) foi observado um efeito sinérgico entre pré tratamento a APD e posterior TT (aproximadamente 1 ciclo logaritmo); já quando utilizado pré TT seguido de tratamento a APD, foi observado apenas um efeito aditivo. Utilizando-se aplicação de APD seguida de TT, foi realizado um planejamento experimental fixando-se a pressão em 200 MPa e variando-se temperatura e tempo do TT e ratio do néctar de manga (brix/acidez), de forma a obter um modelo que descrevesse o processo. Os resultados indicaram que tempo e temperatura afetaram positivamente a inativação e o ratio do néctar afetou negativamente. A partir do modelo foram estabelecidos que processos a 200 MPa seguido de TT a 73,5ºC/10 minutos ou 61,5ºC/20 minutos eram suficientes para obter 5 reduções decimais do bolor. A avaliação desses processos combinados, do processo térmico tradicional (100ºC/10 minutos) e do processo utilizando apenas pressão (300 MPa) sobre o conteúdo de vitamina C e cor do néctar demonstrou uma inativação de vitamina C muito similar para todos os processos (perdas de aproximadamente 45%) e uma melhor retenção de cor para os produtos processados à APD. O desenho do processo de limpeza e sanificação para o equipamento foi considerado eficaz uma vez que reduziu para < 1 UFC.mL-1 a contaminação de A.niger inicial de aproximadamente 106 UFC.mL-1 na água de enxágüe. Foi utilizada concentração de 0,05% de ácido peracético e 2,5% de detergente comercial cujos princípios ativos eram o toluenosulfonato de sódio e cloreto de didecilmetilamônio. O processo de redução de viscosidade do néctar também foi efetivo através de seu pré tratamento com enzimas pectinolíticas e celulases, que reduziram a viscosidade inicial do néctar em 50%. Pelos resultados obtidos no presente trabalho, observa-se que a APD isoladamente ou aplicada junto com TT brando é uma alternativa viável para a inativação de A. niger termorresistente em néctar de manga. O processo teve efeito negativo sobre a vitamina C do néctar de manga, o que pode ser atribuído tanto à presença de oxigênio na amostra quanto à presença de selos metálicos no equipamento (selos de berílio-cobre) que promovem a passagem de íons metálicos para o suco, os quais atuam como pró-oxidantes de vitamina C, agravando a oxidação da vitamina
Abstract: Mango nectar is appreciated by its color and flavor. Due to its high acidity, this nectar can be contaminated by molds and the most important molds are those able to survive to the heating process. The dynamic high pressure (DHP) is a cold treatment used to inactivate microorganisms with better nutritional and sensory retention in food. In this study, the DHP process isolated or combined with mild thermal treatment (TT) was used to inactivate Aspergillus niger in mango nectar. The effects of these processes were evaluated on color and vitamin C retention. In parallel, a methodology was developed to clean in place (CIP) the DHP equipment. A process to reduce the viscosity of mango nectar was also developed. Pressures between 100 and 300 MPa were studied to Aspergillus niger inactivation. Pressure of 300 MPa completely inactivated the initial load (> 6.24 decimal reduction), 200 MPa caused a partial inactivation (2 log cycles) and pressures up to 150 MPa did not inactivate the mold. A synergistic effect was observed when pre treatment of DHP was associated to mild TT (80ºC/ 15 minutes) with increase of 1 log cycle on mold inactivation. However, only an additive effect was observed when pre TT was associated to DHP. An experimental design was carried out using fixed pressure of 200 Mpa followed by mild TT. Temperature and time of thermal treatment and ratio of mango nectar (brix/acidity) was select as experimental design variables. The results indicated that time and temperature affected positively and nectar ratio affected negatively the mold inactivation. By the mathematical model, process of 200 MPa followed by 73.5ºC/10 minutes or by 61.5ºC/20 minutes was able to promote 5 decimal reduction of A. niger. The effect of these processes, the conventional heat and DHP at 300 MPa on vitamin C concentration and nectar color retention was evaluated. The vitamin C losses were around 45% for all processes studied but better color retention was observed on the nectar processed by DHP. The CIP design was considered efficient once it was able to reduce the initial load of A. niger from ~106 CFU.mL-1 to <1 CFU.mL-1. 2.5% of a commercial detergent (active agents: sodium toluenosulfonate and didecylmethilamonium chlorine) and peracetic acid at 0.05% were used in this process. The nectar viscosity reduction was effective by using pectic enzymes and celullase, being able to reduce natural mango nectar viscosity by 50%. The results obtained indicated that DHP isolated or combined with mild thermal treatment are a viable alternative to inactivate A. niger in mango nectar. The process has a negative effect on vitamin C retention. It can be attributed to the oxygen dissolved in mango nectar and also to metals seals of equipment (Be-Cu) which can had promoted an increase in metallic ions concentration in nectar. These ions are pro oxidant of vitamin C, resulting in intense vitamin oxidation
Mestrado
Mestre em Tecnologia de Alimentos

The application of non-thermal processes pulsed electric fields (PEF) and cross-flow micro-filtration (CFMF) continuous to be studied with the purpose of controlling microorganisms in milk. Trends suggesting increased adoption include the study of Food Safety Objectives as a safety criterion, the promotion of sustainable processing, and the implementation of hurdle strategies. While the advance of gentle processing is counteracted by the risk of enhanced resistance due to microbial stress response, several techniques can be applied to quantitatively assess its impact. The objective of this project was to evaluate the effectiveness of microbial inactivation by PEF and CFMF at various steps of milk processing including shelf-life, its comparison with high temperature short time (HTST) pasteurization, and the quantitative assessment of the cross protection resistance to PEF of Escherichia coli O157:H7. Some differences in mesophilics inactivation were observed in milks (fat contents between 1.1% and 3.1%). Increasing the PEF inlet temperature decreased the treatment time by three or two-fold. The combination of CFMF/PEF yielded similar microbial reductions as CFMF/HTST. Higher inactivation of the coliforms was achieved in homogenized cream (12% fat) compared to non-homogenized. The linear relation between electrical conductivity and nutrient content (fat and solids content) was established. In a parallel study the PEF/CFMF sequence resulted in higher inactivation of mesophilics compared to CFMF/PEF and HTST. The shelf life was acceptable for CFMF/PEF and HTST after 7 days, while enterics and psychrotrophs grew more after PEF/CFMF, thermodurics did after HTST. The growth and stress of Escherichia coli O157:H7 in lactose containing broths was monitored by absorbance and fluorescence expression of stress reporters. Growth was explained using a secondary model, and stress response using mechanistic and probabilistic models. PEF inactivation was evaluated following the Weibull distribution after the cells reached stationary phase or maximum fluorescence expression. Similar resistances were observed within the cells grown in lactose broth at 10, 25 or 40°C, as within stressed cells (starved or cold shocked). Cells grown at 45 °C were more resistant compared to the cells grown in acid, high salt concentration while the ones grown at cold temperatures were the weakest.
Dairy Farmers of Ontario, Natural Sciences and Engineering Research Council.

碩士
國立海洋大學
食品科學系碩士在職專班
89
Chinese sausage is a popular product in Taiwan. The preserves are usually added in the product to extend it’s shelf-life. However, the amount used in some commercial products is over the limit. Therefore, in this study we apply the hurdle technology to Chinese sausage processing and preservation instead of single method to improve its quality. Generally, the quality indices of Chinese sausage were represented by the measuring of the color ( a value ) and bacteria (TPC). Among 10 additives used in this study, glucono-delta-lactone, propylene glycol, sodium lactate, potassium sorbate had a more significant effect on the inhibition of bacteria. Therefore, three additives glucono-delta-lactone, propylene glycol, sodium lactate were used as the hurdle factors. To employ these factors systematically, the experiments were designed by using response surface method (RSM). A central rotatable design three-variable and three-level was adopted. The amount of glucono-delta-lactone (0.4％), propylene glycol (0.5％), sodium lactate (1.75％) and potassium sorbate (0.1％) with ±50％ were added to evaluate their combined effect on sausage quality. The results showed the optimal condition for the quality of vacuum packaged Chinese sausage stored at 4℃ was propylene glycol 0.5％, glucono-delta-lactone 0.70∼0.80％ and sodium lactate 1.75∼2.70％. If potassium sorbate was proposed as a factor, the optimal condition was sodium lactate 1.75％, glucono-delta-lactone 0.40∼0.80％ and potassium sorbate 0.18∼0.20％. On the other head, the optimal condition for atmosphere package sausage stored at 25℃ was propylene glycol 0.5％, glucono-delta-lactone 0.50∼0.80％ and sodium lactate 1.00∼3.00％. If potassium sorbate was used, the addition of sodium lactate 1.75％, glucono-delta-lactone 0.40∼0.70％ and potassium sorbate 0.18∼0.20％ could obtain a similar result. There is no significant difference of sensory evaluation between the conventional sausage and the product processed by hurdle technology. However, the latter product had a longer shelf-life than the former.

碩士
中國文化大學
生活應用科學研究所
98
Dried radish is a Chinese traditional pickled product. Because it is an intermediate moisture food, it can preserved longer by food preservative added. However, the over load and illegally preservative added lead people pay more attention to the sanitary quality of dried radish. This study will use the hurdle technology, by gathering several bacteria inhibition factor to increase the quality and economic benefits and decrease the quantity of preservative of dried radish. Furthermore, it will exploit the Taguchi method using orthogonal array and smaller-the-better S/N ratios to confirm the most important of hurdle factor and the optimum process condition of dried radish. The result found that the optimum process condition of dried radish is desalination of raw material in 25 ℃ for 2 hours then dehydration. After that, it will added 0.3 % cinnamon powder, 0.3 % incinerated oyster shell powder and 4.76 % garlic into 100 % sorbitol solution as preservative and soaked for 2 hours. Then, the raw material will to air-dried in 80 ℃ for 30 minutes, and then cooled by 15 ppm ozone for 20 minutes. The result also found that the total count of dried radish which is between 2.39-2.84 log CFU/g processed by optimum process condition (experiment group) and storage at 25 ℃ for 0-5 weeks, and have no yeast and mold growth. On the other hand, the control group of dried radish was found mold growth after 4 weeks storage. Compared with the sensory evaluation score, the result showed the texture, color, flavor and overall acceptability that of the dried radish processed by optimum process condition are better than control group. The result showed dried radish processed by optimum process condition not only increase the shelf-life by gentle processing ways, but also can accepted by consumers.

碩士
國立中興大學
食品暨應用生物科技學系所
99
Since tou-kan curd is high in nutrition and water activity, it’s a very suitable environment for micro-organisms to grow in. Its vacuum packaging is particularly susceptible to contamination from Clostridium botulinum. In order to avoid this risk, this study reduced the dried bean curd’s (both the large and small types) pH to under 4.60 or its water activity to under 0.85. The vacuum packaging was pasteurized in order to develop the contamination prevention hurdle technology. The study prepared a low-pH soaking liquid composed of polyphosphate (U, Tarisan U) or a low water-activity liquid composed of glycerol, propylene glycol, and salt. The bean curd was soaked in this, reducing the pH to below 4.6 and the water activity to below 0.85. The product storage study results showed that reducing the pH and water activity and then using vaccuum packaging and sterilization allowed the bean curd to be preserved for at least four weeks at below 7℃. At below 25℃, it could be preserved for at least 10 days. During the storage period, the total plate count, aerobic quality, and number of anaerobic spores were not tested. The study showed that hurdles such as pH value, water activity, low-temperature sterilization, and cold storage could be combined to produce sanitary vacuum-packaged tou-kan curd products.

碩士
中國文化大學
生活應用科學研究所
97
The dried soybean curd is one of the soybean processed food and its pH value is about 5.8 to 6.6. Dried soybean curd contains plenty of nutrients which make it putrefactive easily, therefore manufacturer usually adds preservative to increase the shelf-life. The present study is going to use the hurdle technology and Taguchi method to increase the shelf-life of the product. The Taguchi method will use the orthogonal array and smaller-the-better S/N ratios to confirm the optimum hurdle factors. Results show that the optimum process is: soaked soybean in 4℃ water for 20 hours and add mix coagulant (CaSO4 0.29% and glucono - δ - lactone 0.4 % and cinnamon powder 0.1%) then press to form the curd, then cooked in boiling water for 25 minute and cooling by 15 ppm ozone air for 40 minute. This process could reduce 99 % of total bacterial count of dried soybean curd. Both soaking and ozone cooling process are the most important factor which contribution above 99%. The predictive value in confirmation experiment is close to the control value, which proved Taguchi method could used to predicate the bacterial growth in dried soybean curd process. Then, the dried soybean curd processed by 3 kind of conditions: (1)add 600 ppm benzoic acid, (2) soak in 30% H2O2 for 5 minute, and (3)processed by the optimum hurdle technology condition, and then incubate them in 37℃ for 12 hours. The total count of final dried soybean curds were 6.94, 0 and 5.18 log CFU/g respectively, and the total count of control group was 7.75 log CFU/g. According to the sensory analysis result show that commercial dried soybean curd is better than the dried soybean curd made by the optimum hurdle technology condition in overall acceptability. However, the dried soybean curd processed by the optimum hurdle technology condition had longer shelf-life. Therefore, the results still can be recommended as a commercial process condition for dried soybean curd make.

碩士
國立臺灣海洋大學
食品科學系
106
This study is aimed to adopt different process variables to improve shelf life of rice cake, treatments including frozen rice cake without preservatives, change frozen storage to refrigerated storage, and control environmental hygiene (lower the relative humidity, spray chlorine dioxide), same proportion degrees brix of pure rice cake and stuffing (40：40, 50：50, 60：60 °Brix), different water content of sprinkled powder (6%, 8%, 10%), different packaging material (PE, KNY/LLDPE, KNY/LLDPE and deoxidizer) as hurdle factors of the manufacturing process of rice cake. Samples were taken at zeroth, fourth, seventh, tenth, fourteenth, fifteenth day, and quality criteria including moisture, water activity, total plate count, yeast and mold, hardness, springiness, chewiness of rice cake under refrigerated storage were analyzed. The results demonstrated that spray 1000 ppm chlorine dioxide was significantly more effective on control air-borne bacteria counts than control the relative humidity under less than 60%. During refrigerated storage, the moisture of each group showed a tendency of rise slowly, while the water activity did not change significantly. Higher concentration (in terms of Brix), low moisture content of sprinkled powder, low permeability packaging material and deoxidizer showed the better hurdle effects on inhibition of microbial growth. Thus, the combination of above hurdle factors, the shelf life could be extended to 15 days under refrigeration as compared to 4 days without adding preservatives. In terms of textural profile analysis, hardness and chewiness were mainly affected by Brix, followed by packaging materials, the variations in springiness was not significantly affected by the hurdle factors. Comprehensively consider both microbial growth and maintenance of texture (lower hardness and higher springiness and chewiness), combined 50：50 °Brix of pure rice cake and stuffing, 8% sprinkled powder, KNY/LLDPE and deoxidizer were the most suitable formula for the product under refrigerated storage.

碩士
國立臺灣大學
食品科技研究所
94
The dried soybean curds from Taoyuan County contains about, 70-90 % water, and water activity is about 0.8.The pH is around 6.0 - 7.0 which provides a good growth condition for spoilage organisms. Generally, after 12 hours of storage under room temperature, dried soybean curd will spoil and form slime on the surface. The spoilage organism isolated from dried soybean curd of Taoyuan County in this study was found to be Acinetobacter sp. Objective of this study is to improve the microbial quality of dried soybean curd in Taoyuan- Daxi area by combine several GRAS materials. According to the results of RSM, we decide the use of benzoic acid (420 ppm) and phosphoric acid (300 ppm) in treating dried soybean curd when the temperature of environment is 25℃ and the pH of soybean curd is 5 to minimize the growth of Serratia liquefaciens. The growth of indicator organisms, Serratia liquefaciens, can be inhibited by anise, cinnamon and clove and the minimum inhibitory concentration for anise, cinnamon, and clove are 6 %, 12% and 20 %, respectively. Pseudomonas fluorescens can be inhibited by clove, with a minimum inhibitory concentration of 16 %. While Acinetobacter lwoffii can be inhibited by cinnamon and clove, both with a minimum inhibitory concentration of 3 %. The combinations of benzoic acid 420 ppm, phosphoric acid or citric acid 300 ppm, cinnamon 3 %, anise 4 %, and clove 3 % in the bittern could extend the shelf life of dried soybean curd from 12 hours to 48 hours under 25℃. The total count of dried soybean curd decrease with the storage time under 5℃.