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1
Gibson, Michael W. "Physico-chemical and shelf-life between baked and extruded pet foods". Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/20410.
Testo completoAbstract (sommario):
Master of ScienceGrain Science and Industry
Sajid Alavi
The U.S. pet food market was approximately worth $22 billion in 2013. Further growth is predicted at a pace faster than most major human food product categories. More than 60% of pet food products are processed using extrusion, and a significant proportion is produced using baking. However, research is lacking on fundamental process and product differences between extrusion and baking. The current study focuses on this aspect and also in-depth characterization of process and product quality. Three iso-nutritional diets were formulated for dry expanded dog food using 0%, 7% and 15% fresh meat inclusion. Major variations between diets were inclusion rates of mechanically deboned chicken, cereal grains, and poultry fat. Each diet was processed with a single screw extruder using various thermal and/or mechanical energy inputs (obtained by varying pre-conditioner stem injection and/or extruder screw speeds). Diets were also processed by baking using a 30 foot experimental oven at 425°F, although the fresh meat inclusion was at 0%, 10% and 20% levels. Proximate analysis of products was conducted. Products were also characterized for physico-chemical properties such as bulk density, piece density, expansion ratio, degree of gelatinization and textural attributes. As fresh meat inclusion increased (0–15%), expansion ratio (4.1–3.5) decreased irrespective of extrusion treatment. Expansion was not evident in the baked kibbles, and bulk and piece densities were up to 56% higher for baked versus extruded kibbles. Textural analysis of extruded kibbles revealed serrated force-deformation response, typical of cellular products, with peak hardness of 2.9–1.5 kgf. On the other hand, baked products had a ‘smooth’ force-deformation response with higher peak hardness than extruded products (up to 3 kgf). Microbial counts for baked products were higher than extruded products, and rancidity profiles as obtained from gas chromatography also had marked differences. The extrusion process was characterized by detailed mass and energy balance analyses, and compared with baking that lacks mechanical energy input. Results from this study provide a useful bench-mark for dry expanded pet food product quality and commonly used processing technologies.
2
Tyrer, Helen Linsey. "The effect of storage temperature on the measured predicted shelf life of chilled prepared foods". Thesis, Manchester Metropolitan University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266441.
Testo completo
3
Larsen, Ross Allen Andrew. "Food Shelf Life: Estimation and Experimental Design". Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1315.pdf.
Testo completo
4
Weber, Rebecca J. "Shelf life extension of corn tortillas". Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/1115.
Testo completo
5
Young, Helen M. "Factors affecting the quality and shelf-life of cooked chilled foods with special reference to full meal vending". Thesis, Bournemouth University, 1986. http://eprints.bournemouth.ac.uk/424/.
Testo completoAbstract (sommario):
A nation wide survey of the vending industry indicated that the shelf-life of chilled menu items served from vending machines rarely exceeded 24 hours. This necessitated food production and distribution to vending sites on a daily basis. The short life coupled with unpredictable consumer demand may result in high food wastage rates. Vacuum and modified atmosphere packaging (MAP) are known to improve stored raw food quality. In order to optimize the quality and shelf-life of vended foods, the effects of these techniques and length of storage time on menu items were studied. Chicken drumsticks and chicken a la king were either individually cling wrapped, vacuum packed or packed under modified atmosphere (70% CO , 30N 0) and stored for up to 21 days in a chilled foot vending machine. The growth of naturally occurring micro-organisms was delayed in vacuum packed samples, compared with cling wrapped samples. However, direct inoculation studies indicated that this effect was dependent on the nature of the initial microflora. The public health risk of serving cooked food from vending machines was assessed by means of a survey of the operating temperatures of chilled food vending machines and a review of the growth characteristics of the major food poisoning micro-organisms. Th8 surveyed machines were able to maintain temperatures below 5 C, although this temperature was not universally found. The sensory quality of the chicken samples was examined by two trained taste panels and also a consumer panel. Stepwise discriminant analysis of the trained panel scores indicated that packaging and length of storage had a distinctive and unique effect on the sensory quality of both products. The mean consumer scores were used to construct significant (p<0.05) regression models, which showed that on average consumers preferred the fresh unpackaged sample and least preferred the cling wrapped samples. However, when the consumer scores of individuals were examined by means of Prefmap analysis, subgroups were found to exist within the population that held polar viewpoints in opinion. The results show that MAP and vacuum packaging may be used in place of cling wrapping to extend the shelf-life of certain vended menu items, but of more immediate importance to the vending industry is the implementation of proper temperature control to ensure a hazard free syste
6
Feliciano, Lizanel. "Shelf-life Extension of Seafood Using Sanitized Ice". The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1252965039.
Testo completo
7
Mohammadbeygy, Tina. "Shelf life extension of preformed pizza using ultraviolet light". Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=123317.
Testo completoAbstract (sommario):
Mold is a common post-processing contaminant in pizza. Since contamination could occur in post-baking process, other safety barriers in addition to packaging are needed to ensure the continued safety of preformed pizza. The present research investigated the use of pulsed UV-light for the purpose of decontaminating Penicillium roqueforti on the surfaces of agar media, bread and preformed pizza. In the first step in the present study, the spatial distribution of pulsed UV-light was investigated. The Petri plates inoculated with Penicillium roqueforti were treated for10 min in the first three effective levels in the treatment chamber (5, 10 and 15 cm). 30, 75 and 90 percent of the surface area of the tray was exposed to pulsed light at 5, 10 and 15 cm from pulsed light lamp, respectively. Apple juice inoculated with E. coli was treated with pulsed UV-light at the same distances (5, 10 and 15 cm) from the light source, 3 voltage inputs (400, 750 and 1,000 V) and 3 treatment times (1, 5 and 10 min). The log reduction in E. coli population treated by pulsed UV-light varied from 1.4 to 2.05 log CFU ml-1. In the second phase of the study, the consistency of mold growth on the surface of flat bread was investigated using two different methods of inoculation; random spot and spread. Two different inoculum populations (102 and 103 CFU ml-1) were also used to assess the effect of inoculum concentration on the distribution and consistency of mold growth. Samples inoculated with 102 CFU ml-1 yielded more homogenously distributed colonies. In the third phase of the study, sensory and microbiological analyses were used to evaluate the effectiveness of pulsed light treatment for shelf life extension of pizza and bread. Up to 40 days shelf-life extension was achieved for 8, 32, and 40 percent of samples with minimal, intermediate and maximal pulsed light treatment, respectively. In the fourth phase of the study, the effectiveness of pulsed light was evaluated for the decontamination of Penicillium roqueforti on the surface of solid agar. Process parameters evaluated were treatment time (1, 3, 5, 7 and 10 min) and voltage input (500, 750 and 1,000 V). The population of Penicillium roqueforti was reduced after 10 min of exposure to pulsed light by 3.74, 5.36 and 6.14 log CFU ml-1, respectively for 500, 750 and 1,000 V. The inactivation data were used to construct models to estimate the inactivation. The results presented in this study indicate that inactivation kinetics was best described by the Weibull model with the smallest root mean squared error (RMSE) (R2 ≥ 0.92). Finally in the last phase of study, culture-dependent and independent methods were applied to study the ecology of preformed pizza. The average population of mesophilic aerobic bacteria (MAB), mesophilic anaerobic bacteria (MANB), lactic acid bacteria (LAB), molds and yeasts (M+Y) were 6.6±0.5, less than 2.4, 2.8±0.6 and 5.4±0.4 log CFU g-1, respectively. Molecular methods incorporating conventional PCR targeting the 18S rRNA gene of fungi, TA cloning of PCR-amplified fragments and sequencing were carried out to detect spoilage fungi in naturally spoiled pre-formed pizza. The cloning approach enabled the putative identification of Saccharomyces cerevisiae, Saccharomyces sp. WW-W23, Penicillium expansum, Penicillium freii, Penicillium sp. HSL, Penicillium sp. ljg1, Rhodotorula mucilaginosa, Monascus fuliginosus, Hordeum jubatum, Galactomyces geotrichum strains as well as uncultured fungus and uncultured eukaryote clones. Overall, pulsed UV-light was found to have a potential use for the decontamination of spoilage microorganisms on the surfaces of solid agar and bakery products. However, further investigation using higher treatment voltages is necessary in order to achieve a higher target decontamination of P. roqueforti.La pizza pré-cuisinée est couramment contaminée par la moisissure. Puisque la contamination pourrait se produire durant les procédés d'après cuisson, d'autres mesures, en plus de l'emballage, sont nécessaires pour assurer la sécurité permanente des pizzas pré-cuisinée. Cette recherche a examiné l'utilisation de la lumière UV pulsée pour décontaminer Penicillium roqueforti sur la surface de l'agar solide, du pain et de pizzas préformées.Dans la première étape de la présente étude, les paramètres critiques du procédé ont été optimisés pour améliorer l'efficacité des traitements à la lumière pulsée. Les boîtes de Petri inoculées avec Penicillium roqueforti ont été traitées 10 min dans une chambre de traitement pour les trois premiers niveaux d'efficacité (5, 10 et 15 cm). Les résultats démontrent que 30, 75 et 90 pour cent de la surface du plateau a été exposée à la lumière pulsée à 5, 10 et 15 cm respectivement de la source lumineuse. La réduction en log de la population de E. coli traitée par la lumière UV pulsée varie de 1.4 à 2.05 log UFC ml-1.Dans la deuxième phase de l'étude, la cohérence de la croissance des moisissures (Penicillium roqueforti) sur la surface du pain plat a été étudiée en utilisant deux méthodes différentes d'inoculation : par inoculation ponctuelle aléatoire et par étalement. Deux populations d'inoculum différentes (102 et 103 UFC ml-1) ont également été utilisées pour évaluer l'effet de la densité de l'inoculum sur la distribution et la cohérence de la croissance de moisissures. Les échantillons inoculés avec 102 UFC ml-1 ont donné une distribution des colonies plus homogène. À la troisième phase de cette étude, l'analyse sensorielle et microbiologique, ont été utilisées pour évaluer l'efficacité du traitement à la lumière pulsée pour prolonger la durée de vie de la pizza et du pain. Jusqu'à 40 jours de prolongement de la durée de conservation a été obtenue pour 8, 32 et 40 pour cent des échantillons après un traitement à la lumière pulsée minimal, intermédiaire et maximal, respectivement. Dans la quatrième phase de l'étude, l'efficacité d'une lumière UV pulsée à large spectre a été évaluée pour la décontamination de Penicillium roqueforti sur la surface de l'agar solide. La population de Penicillium roqueforti a été réduite après 10 minutes d'exposition à la lumière pulsée par 3.74, 5.36 et 6.14 log UFC ml-1 respectivement pour 500, 750 et 1000 V. Les résultats présentés dans cette étude indiquent que d'inactivation a été mieux décrite par le modèle de Weibull avec la plus petite erreur de moyenne quadratique (RMSE) (R2 ≥ 0.92). Finalement, dans la dernière phase de l'étude, des méthodes dépendantes ou indépendantes des conditions de culture ont été appliquées pour étudier l'écologie des pizzas pré-cuisinées. La moyenne de la population des bactéries mésophiles aérobies (BMA), des bactéries mésophiles anaérobies (BMNA), des bactéries lactiques (BL), des moisissures et des levures (M+L) étaient respectivement de 6.6 ± 0.5, inférieur à 2.4, 2.8 ± 0.6 et 5.4 ± 0.4 log UFC g-1. Les méthodes moléculaires incorporant la PCR conventionnelle ciblant le gène de l'ARNr 18S des champignons, le clonage TA de fragments amplifiés par PCR et le séquençage ont été réalisées pour détecter les champignons altérant les pizzas pré-cuisinées naturellement contaminées. L'approche du clonage a permis l'identification présumée de souches de Saccharomyces cerevisiae, Saccharomyces sp. WW- W23, Penicillium expansum, Penicillium freii, Penicillium sp. HSL, Penicillium sp. ljg1, Rhodotorula mucilaginosa, Monascus fuliginosus, Hordeum jubatum , Geotrichum galactomyces ainsi que des champignons et eucaryotes non cultivés.Dans l'ensemble, la lumière UV pulsée a démontré avoir un potentiel d'utilisation pour la décontamination des microorganismes altérant les surfaces d'agar solide et les produits de boulangerie.
8
Gray, Morgan. "Evaluation of oxidized rendered protein meals in pet foods". Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/20379.
Testo completoAbstract (sommario):
Master of ScienceGrain Science and Industry
Greg Aldrich
Rendered protein meal is an important source of dietary protein and fat in pet food. However, fats in rendered meals can oxidize rapidly if not protected. The most common measurement of oxidation is the peroxide value (PV), but the analysis is highly variable. Additionally, the incorporation of oxidized protein further shortens its shelf life. Therefore, our objectives were to evaluate methods to measure fat quality in rendered protein meals and to determine the effect of increasingly oxidized protein meals on the shelf life of extruded pet foods. In Experiment 1, samples of five chicken byproduct meals (CBPM) from each of three locations and five beef meat and bone meals (BMBM) from each of two locations were analyzed for PV, anisidine value (AV), and thiobarbituric acid reactive substances (TBARS). The PV varied by method and location (P < 0.05). The alternative oxidation analytical methods, AV and TBARS, were not strongly correlated to PV (R² > 0.01). In Experiment 2, one metric ton of each unpreserved CBPM and unpreserved BMBM were collected and left unpreserved (U) or preserved with either ethoxyquin (E) or mixed tocopherols (T). These were held at ambient conditions (25°C, 51% RH) and monitored for PV and AV until values plateaued (41 and 63 days for CBPM and BMBM, respectively). Each “aged” meal was then incorporated into a model extruded cat food diet (~30% protein). Samples of kibble for each treatment were collected and stored at an elevated temperature and humidity (40°C, 70% RH) for 18 weeks and an ambient temperature and humidity (~22°C, 45% RH) for 12 months. The initial reduction (P < 0.05) in PV of the U (highly oxidized) BMBM and CBPM after processing suggests oxidation levels were diluted by food production. The oxidized meal led to a shorter shelf life (P < 0.05) in the finished food by PV analysis; but, sensory analysis by quick assessment did not completely corroborate these findings. These results suggest that PV doesn’t fully describe rendered protein meal stability or have a direct impact on shelf life for consumers; but may have a negative impact on pets due to oxidized lipid consumption.
9
Lambert, Anne. "Effects of modified atmosphere packaging and low-dose irradiation on the shelf life and microbiological safety of fresh pork". Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=70219.
Testo completoAbstract (sommario):
The effects of irradiation dose (0, 0.5 and 1.0 kGy), various gas atmospheres and storage temperature (5, 15 and 25$ sp circ$C) on the physical, chemical, microbiological, and organoleptic changes in fresh pork were studied using factorial design experiments. The effects on toxin production by Clostridium botulinum were also investigated using challenge studies. Shelf life could be extended to 21 d when product was packaged in 0% O$ sb2$, irradiated at 1.0 kGy and stored at 5$ sp circ$C compared to 4 d for control samples. While the presence of O$ sb2$ in the package headspace enhanced the antimicrobial effects of low-dose irradiation, it adversely affected the organoleptic qualities of pork. Botulinum toxin was detected after only 2 d in all inoculated treatments stored at 25$ sp circ$C. At 15$ sp circ$C, toxin was produced faster when pork was initially packaged with O$ sb2$ or low levels of CO$ sb2$ (15-30%) as compared to 100% N$ sb2$. Higher levels of CO$ sb2$ (45-75%) delayed toxin production. In most treatments, spoilage preceded toxigenesis. Models were developed relating the above factors to the time until toxin production and to the probability of toxigenesis. Temperature, initial O$ sb2$ and irradiation were all significant factors.
10
Chitundu, Elizabeth Malama. "Studies on the shelf life of macadamia nuts". Thesis, Richmond, N.S.W. : School of Food Science, Faculty of Science and Technology, University of Western Sydney, Hawkesbury, 1994. http://handle.uws.edu.au:8081/1959.7/37.
Testo completoAbstract (sommario):
Shelf life studies of raw Macadamia integrifolia nuts were carried out at different storage temperatures, relative humidities and time. An accelerated shelf life test was conducted, and the influence of water activity on kernel texture was studied. The antioxidants naturally present were identified by the use of thin layer chromatography. Accelerated shelf life tests showed that hydrolytic rancidity followed apparent zero order kinetics within the water activity range of 0.3 to 0.5. Oxidative rancidity measured by peroxide value appeared to follow different orders of reaction at different temperatures. At two months of storage rancidity was detected at which the headspace concentration of hexanal was 0.39 ppm and a peroxide value of 0.37 meq/kg. Headspace gas chromatography was done to find a quick and effective method for measuring oxidative rancidity. The presence of natural antioxidants was verified to explain the shelf life of macadamia nuts. In textural study, correlations were found between subjective and objective measurements. The product became unacceptable organoleptically above water activity 0.415 when stored at 20 degrees C. This level was established as the critical water activity. There is a need to establish a water activity at which the consumer is likely to reject the product.
11
Joubert, Marisa. "The manipulation of ostrich meat quality, composition and shelf life". Thesis, Stellenbosch : University of Stellenbosch, 2003. http://hdl.handle.net/10019.1/16341.
Testo completoAbstract (sommario):
Thesis (MScVoedselwet)--University of Stellenbosch, 2003.ENGLISH ABSTRACT: Two experiments were conducted in order to manipulate the physical and chemical properties and shelf life of ostrich meat. Experiment 1: The effect of dietary fish oil rich in n-3 fatty acids on the organoleptic, fatty acid and physicochemical characteristics of ostrich meat. The diet of four ostrich groups (15 birds per group), approximately 3 months of age (ca. 41 kg live weight) grazing a predominantly oats pasture, was supplemented with a diet containing 6.7% fish oil. The birds received a supplement of either 0 (diet 1), 800 (diet 2), 1600 (diet 3) or 2400 g (diet 4) DM/day resulting in the consumption of 0 (diet 1), 14.5 (diet 2), 29 (diet 3) and 43.5 (diet 4) g fish oil per day. The ostriches were slaughtered at 10 months of age (ca. 70 kg live weight). An increase in the amount of fish oil consumed was found to have had statistically no significant effect on the sensory characteristics of the M. iliofibularis, although there was a tendency towards an increase in ‘fishiness’, for both aroma and flavour. However, increased concentrations of fish oil had a significant effect on the aroma and flavour of the abdominal fat pads. The muscle pHf and muscle lightness (L*) reflected a significant reduction with increased fish oil levels. The increased feed intake, on the other hand, had no effect on the chemical composition (moisture, protein, fat and ash content) of the meat. The fatty acid profile of both fat and meat was affected by the consumption of fish oil. The SFA concentration increased, while the PUFA concentration decreased, with an increase in feed intake. The MUFA concentration remained constant for all four groups. Experiment 2: The effect of dietary vitamin E and the type of packaging on the sensory quality, physicochemical composition and shelf life of ostrich meat. Two groups of ostriches (35 birds per group; ca. 3 months old) were fed diets containing either 40 mg/kg feed vitamin E (control) or 150 mg/kg feed Vitamin E for nine months. The birds were slaughtered at 12 months of age. The effect of different the levels of vitamin E and heat shrink treatment of vacuum packaging material on the shelf life of refrigerated (0°C) ostrich M. flexor cruris lateralis, was evaluated over 81 days. Vitamin E and heat shrink treatments were found to have had no significant effect on the sensory characteristics; off-meat aroma, sourness, juiciness and mealiness. Rancidity was found to be slightly more pronounced (although not statistical significant) in the vitamin E and heat shrink groups than in the feed control and vacuum-packed groups. A significant decrease in the organoleptic quality of the meat, over a 40 day shelf life period, was observed. The pH and muscle tenderness showed a significant reduction with increased storage time. The purge loss in the package increased over time with no change in muscle drip loss. The colour, conjugated dienoic acid and fatty acid content showed no significant changes over time or with regards to treatment. The total viable counts and coliform numbers in the muscle increased over time, with the coliforms being slightly suppressed by the inclusion of vitamin E in the diet. A microbiological safe shelf life of 40 days at 0°C was obtained.
AFRIKAANSE OPSOMMING: Twee eksperimente is uitgevoer om die fisiese en chemiese eienskappe, asook die rakleeftyd van volstruisvleis, te manipuleer. Eksperiment 1: Die effek van visolie, ryk aan n-3 vetsure, op die organoleptiese, vetsuur- en fisies-chemiese eienskappe van volstruisvleis. Die dieet van vier groepe volstruise (15 voëls per groep), ongeveer 3 maande oud (ca. 41 kg lewende massa) wat ‘n hawer weiding bewei het, is aangevul met ‘n byvoedingsmengsel wat 6.7% visolie bevat en in toenemende hoeveelhede vir die groepe volstruise gevoer is. Die voëls het ‘n aanvulling van 0 (dieet 1), 800 (dieet 2), 1600 (dieet 3) of 2400 g (dieet 4) DM/dag ontvang wat gelei het tot ‘n inname van 0 (dieet 1), 14.5 (dieet 2), 29 (dieet 3) en 43.5 (dieet 4) g visolie per dag. Die volstruise is op ‘n ouderdom van 10 maande geslag (ca. 70 kg lewende massa). ‘n Toename in die hoeveelheid visolie ingeneem, het geen statisties betekenisvolle effek op die sensoriese eienskappe van die M. ilifibularis gehad nie, alhoewel daar ‘n tendens was vir ‘n toename tot ‘n ‘visagtige’ aroma en smaak. ‘n Toename in die konsentrasie visolie het egter ‘n betekenisvolle effek op die ‘visagtige’ aroma en smaak van die abdominale vet neerslae gehad. Die spier pHf en spier ligtheid (L*) het ‘n betekenisvolle afname met toename in voer inname getoon. Die verhoogde olie inname het egter geen effek op die chemiese samestelling (vog-, proteïen-, vet- en asinhoud) van die vleis gehad nie. Die vetsuurprofiel van beide die abdominale vet neerslae en die vleis is deur die inname van visolie verander. Die versadigde vetsuurkonsentrasie het verhoog terwyl die poli-onversadigde vetsuurkonsentrasie verlaag het met ‘n toename in rantsoenvlakke. Die mono-onversadigde vetsuurkonsentrasie het egter konstant gebly vir al vier groepe. Eksperiment 2: Die effek van vitamien E en die tipe verpakking op die sensoriese kwaliteit, fisies-chemiese samestelling en rakleeftyd van volstruisvleis. Twee groepe volstruise (35 voëls per groep, ongeveer 3 maande oud) het voere oor ‘n tydperk van nege maande ontvang wat 40 mg vitamien E/kg voer (kontrole) of 150 mg vitamien E/kg voer bevat het. Die voëls is op 12 maande ouderdom geslag. Die effek van die verskillende vlakke van vitamien E en hitte-behandeling van die verpakkings materiaal op die rakleeftyd van verkoelde (0°C) volstruis M. flexor cruris lateralis, is oor 81 dae geëvalueer. Vitamien E en die hitte-behandeling het geen betekenisvolle effek op die organoleptiese eienskappe (af-vleis aroma, suurheid, sappigheid en melerigheid) gehad nie. Galsterigheid was ‘n bietjie meer gedefinieerd (anie-betekenisvol) in die vitamien E en hitte behandelde groepe as in die rantsoen kontrole en vakuum verpakte vleis. ‘n Betekenisvolle afname is waargeneem in die organoleptiese kwaliteit van die vleis oor ‘n 40 dae rakleeftyd periode. Die pH en taaiheid van die spier het betekenisvol afgeneem met ‘n toename in bergingsperiode. Die drup verlies tydens verpakking het ook oor tyd toegeneem, terwyl geen verandering in die analitiese drup verlies van die spier verkry is nie. Die kleur, gekonjugeerde dieensuur en vetsuursamestelling het geen verandering oor tyd of ten opsigte van behandeling getoon nie. Die Totale Lewendig Seltelling en coliforme het toegeneem oor tyd, terwyl die coliforme deur die byvoeging van vitamien E tot ‘n mate onderdruk is. ‘n Mikrobiologies veilige rakleeftyd van 40 dae is verkry.
12
Miller, Craig William, University of Western Sydney, of Science Technology and Environment College e of Science Food and Horticulture School. "A study of packaging methods to reduce the dissolved oxygen content in probiotic yoghurt". THESIS_CSTE_SFH_Miller_C.xml, 2003. http://handle.uws.edu.au:8081/1959.7/633.
Testo completoAbstract (sommario):
Probiotic bacteria are added to commercial yoghurts as adjunct cultures, to impart health benefits to consumers. To gain maximum therapeutic benefit, the bacteria must remain viable over the shelf life of the yoghurt. Studies have shown, however, that the viability of these bacteria decreases significantly over this period and in some products, is negligible prior to the expiry date. Some strains of probiotic bacteria are oxygen sensitive. Yoghurt has been found to contain a significant concentration of dissolved oxygen and it has been proposed that this has a negative effect on probiotic viability. In this research, several tests were conducted and observations made. Experiments were conducted with non-commercial probiotic cultures to observe the effect of low oxygen environment on probiotic viability. No significant difference existed in viability between probiotic bacteria stored in oxygen reduced yoghurt and regular yoghurt. All yoghurt stored in oxygen barrier packaging material displayed enhanced shelf-life properties, this was observed in replicated experiments. Oxygen barrier packaging combined with an oxygen scavenging material was found to be the most effective oxygen removal system, particularly when used with set type yoghurt.Doctor of Philosophy (PhD)
13
Kurt, Esra. "Associations between lipid composition, shelf life and sensory quality in ruminant meats". Thesis, University of Bristol, 1999. http://hdl.handle.net/1983/a77d9a0c-f888-4650-b6b8-7c1b8f5cee45.
Testo completo
14
Zhang, Dong. "Chemical Composition, Probiotic Survivability and Shelf Life Studies of Symbiotic Buttermilk". ScholarWorks @ UVM, 2015. http://scholarworks.uvm.edu/graddis/369.
Testo completoAbstract (sommario):
Cultured buttermilk is becoming popular as an ingredient for bakery applications and for direct consumption in the U.S.. The objective of this study was to develop a symbiotic cultured buttermilk, containing inulin as a prebiotic and the probiotics Lactobacillus acidophilus and Bifidobacterium spp. The cultured buttermilk was prepared using a commercial mesophilic starter CHN22 (Lactococcus lactis subsp. cremoris, Lactococcus lactis subsp. lactis, Leuconstoc mesenteorides subsp. cremoris, Lactococcus lactis subsp. lactis biovar diacetylactis) and the probiotics. The control buttermilk was prepared using CHN22 and the symbiotic buttermilk were analyzed for chemical composition, probiotics survivability, mold, yeast and coliform counts. Changes in pH, titratable acidity and proteolysis were also determined during storage at 4℃ for 12 weeks. The chemical composition of the control and symbiotic buttermilk were: protein 3.29±0.05 and 3.30±0.02%; fat 3.28±0.04 and 3.26±0.06%; carbohydrate 4.55±0.05 and 5.16±0.06%; total solids 11.81±0.05 and 12.42±0.03%; ash 0.69±0.03 and 0.70±0.01%, respectively. The populations of both Lactobacillus acidophilus and Bifidobacterium spp. were initially above 107 cfu/ml and remained 106cfu/ml during the 12-week study and no mold or yeast were detected. There were significant differences in pH and titratable acidity between the control and symbiotic buttermilk (p<0.05). There was no considerable difference in proteolysis between the two samples. Results indicated that the symbiotic buttermilk might be considered as a functional food as survival of probiotics was significantly higher compared to other fermented foods.
Key words: Buttermilk, Symbiotic, Inulin, Functional foods, Lactobacillus acidophilus, Bifidobacterium spp.
15
Simpson, Marian V. "Shelf life and microbiological safety studies on minimally processed, refrigerated "sous-vide" products". Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41134.
Testo completoAbstract (sommario):
Previous results indicated that lactic acid bacteria (LAB) and Bacillus spores were the predominant spoilage microorganisms in minimally processed products after 35 days storage at 15$ sp circ$C. Furthermore, most packages were swollen due to carbon dioxide production by the LAB. The fact that spores survived mild heat treatment is of concern since it implies that other more pathogenic spores, e.g. Clostridium botulinum would also survive and may pose a public health problem in products stored at 15$ sp circ$C. As such, the influence of combination treatments (viz., mild heat processing treatment, pH, water activity, storage temperature, lactic acid bacteria) were evaluated through challenge studies with selected strains of C. botulinum type A, B, and E spores. The shelf life and safety of the products following a 13D process at 75$ sp circ$C, could be extended to $ ge$42 days by a combination of pH $ le$ 5.0 and storage at 5$ sp circ$C. Other combination treatments were also effective in controlling growth of, and toxin formation in the products by C. botulinum. For instance, botulinum toxin was not detected until day 35 in inoculated spaghetti and meat sauce products (pH 5.25 and a$ sb{w}$ 0.992) with type A and B spores and stored at 15$ sp circ$C. Shelf life extension and inhibition of toxin production was also possible through reductions in a$ sb{w}$ levels achieved by addition of 1-3% salt (w/w) to the products. Water activity levels of $ le$0.983 prevented botulinum toxin production in the minimally processed spaghetti and meat sauce product for $ ge$42 days during storage at 15$ sp circ$C.Similar trends were observed in sous-vide rice and salmon products. Furthermore, when sodium lactate was used as the humectant to lower the a$ sb{w}$ of this product, toxin production was also delayed, but not to the same extent as achieved with NaCl. When two strains of bacteriocin-producing lactic acid bacteria were co-inoculated separately in the sous-vide rice and salmon products that had been challenged with C. botulinum type E spores, toxin formation was only slightly delayed in products with added NaCl (1%), while toxin formation was neither delayed nor prevented in similarly lactic acid bacteria-treated samples with no added NaCl. Furthermore, in most of the products in which botulinum toxin was detected, spoilage preceded toxigenesis, however, in some samples stored at 5$ sp circ$C toxigenesis preceded spoilage. Addition of $ alpha$-2-macroglobulin at a level of 2.7 ppm did not delay or prevent toxin formation in the product. Microwave heating of products at half-power or full power (800 Watts) for 5 to 10 min proved effective in inactivating all of the pre-formed toxin in toxic samples. (Abstract shortened by UMI.)
16
Ḥasan, Ṣalāḥ 1964. "Methods to extend the mold free shelf life of pizza crusts". Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27337.
Testo completoAbstract (sommario):
In this research, initial studies were done to determine the effect of various methods of presentation involving chemical preservatives, water activity ($ rm a sb{w}$), and modified atmosphere packaging (MAP) on mold growth in an agar model system. Results showed that preservatives could completely inhibit mold growth for 2-40d depending on concentration and pH used. Gas packaging (60% or 80% CO$ sb2$), oxygen absorbents, alone or in combination with potassium sorbate, could also inhibit mold growth for $>$40d at ambient storage temperature using a Response Surface Methodology (RSM) approach.The effects of various methods of applying potassium sorbate into pizza crusts via direct incorporation into the batter, surface spraying, and impregnation of packaging material with potassium sorbate to control mold spoilage of pizza crusts were also investigated. Results showed that the antimicrobial effect of potassium sorbate was negligible when the packaging material was impregnated with the inhibitor but more pronounced when it was incorporated directly into the dough or sprayed onto the product's surface. The inhibitory effect of potassium sorbate increased as both the pH and the inoculum level decreased.
Shelf life studies using low concentrations of potassium sorbate (1000 and 2000 p.p.m.) and MAP, alone and in combination with each other, showed that potassium sorbate, gas packaging or oxygen absorbents (Ageless FX) could extend the shelf life of pizza crusts and decrease the growth rate of molds, bacteria and yeast. Furthermore, when pizza crusts were packaged in 60% CO$ sb2$ or with an oxygen absorbent, in combination with potassium sorbate (1000-2000 p.p.m.), a shelf life of 42d was possible without compromising the sensory shelf life of the product. (Abstract shortened by UMI.)
17
Rodgers, Svetlana. "Development of a bio-preservation method for extended shelf-life cook-chill systems /". View thesis, 2003. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030721.150526/index.html.
Testo completoAbstract (sommario):
Thesis (PhD) -- University of Western Sydney, 2003."A thesis submitted for degree of Doctor of Philosophy, Centre for Advanced Food Research, School of Science, Food & Horticulture, University of Western Sydney, Hawkesbury campus, Richmond, Australia, January 2003" Bibliography: leaves 199-227.
18
Lütke, Entrup Matthias. "Advanced planning in fresh food industries : integrating shelf life into production planning /". Heidelberg ; New York : Physica-Verlag, 2005. http://www.springerlink.com/content/978-3-7908-1592-4.
Testo completo
19
Rodgers, Svetlana. "Development of a bio-preservation method for extended shelf-life cook-chill systems". Thesis, View thesis, 2003. http://handle.uws.edu.au:8081/1959.7/23237.
Testo completoAbstract (sommario):
Extended shelf-life cook-chill meals can pose a potential risk of botulism if they are subjected to a temperature abuse. Spores of group II non-proteolytic Clostridium botulinum can survive the mild heat treatment typically given to these products and can grow at refrigeration temperatures. To circumvent this safety issue, existing preservation methods can either affect the sensory properties of these foods or damage their image. Therefore, additional natural preservation hurdles are needed. Thus, the aim of this study was to develop a novel bio-preservation method based on the principle of antibiosis between protective cultures (PCs) and C. botulinum. Consequently, the objectives were to select effective anti-botulinal cultures and study their inhibition pattern in microbiological media and foods, identify the conditions for effective inhibition and the nature of the antibiosis. This research demonstrates for the first time that the bacteriocinogenic protective cultures inoculated at high levels had an anti-botulinal effect in a range of commercial cook-chill products, which supported active growth of non-proteolytic C. botulinum. The protocol for commercial application of the protective cultures was developed.
20
Bagdan, Galen Corey. "Shelf-life extension studies on an omega-3 enriched breakfast cereal". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0033/MQ64315.pdf.
Testo completo
21
Thor, Nandan G. "Using Computer Vision to Build a Predictive Model of Fruit Shelf-life". DigitalCommons@CalPoly, 2017. https://digitalcommons.calpoly.edu/theses/1721.
Testo completoAbstract (sommario):
Computer vision is becoming a ubiquitous technology in many industries on account of its speed, accuracy, and long-term cost efficacy. The ability of a computer vision system to quickly and efficiently make quality decisions has made computer vision a popular technology on inspection lines. However, few companies in the agriculture industry use computer vision because of the non-uniformity of sellable produce. The small number of agriculture companies that do utilize computer vision use it to extract features for size sorting or for a binary grading system: if the piece of fruit has a certain color, certain shape, and certain size, then it passes and is sold. If any of the above criteria are not met, then the fruit is discarded. This is a highly wasteful and relatively subjective process.
This thesis proposes a process to undergo to use computer vision techniques to extract features of fruit and build a model to predict shelf-life based on the extracted features. Fundamentally, the existing agricultural processes that do use computer vision base their distribution decisions on current produce characteristics. The process proposed in this thesis uses current characteristics to predict future characteristics, which leads to more informed distribution decisions. By modeling future characteristics, the process proposed will allow fruit characterized as “unfit to sell” by existing standards to still be utilized (i.e. if the fruit is too ripe to ship across the country, it can still be sold locally) which decreases food waste and increases profit. The process described also removes the subjectivity present in current fruit grading systems. Further, better informed distribution decisions will save money in storage costs and excess inventory.
The proposed process consists of discrete steps to follow. The first step is to choose a fruit of interest to model. Then, the first of two experiments is performed. Sugar content of a large sample of fruit are destructively measured (using a refractometer) to correlate sugar content to a color range. This step is necessary to determine the end-point of data collection because stages of ripeness are fundamentally subjective. The literature is consulted to determine “ripe” sugar content of the fruit and the first experiment is undertaken to correlate a color range that corresponds to the “ripe” sugar content. This feature range serves as the end-point of the second experiment. The second experiment is large-scale data collection of the fruit of interest, with features being recorded every day, until the fruit reaches end-of-life as determined by the first experiment. Then, computer vision is used to perform feature extraction and features are recorded over each sample fruit’s lifetime. The recorded data is then analyzed with regression and other techniques to build a model of the fruit’s shelf-life. The model is finally validated. This thesis uses bananas as a proof of concept of the proposed process.
22
Zare, Zahra. "High pressure processing of fresh tuna fish and its effects on shelf life". Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18212.
Testo completoAbstract (sommario):
Tuna is highly perishable and has been implicated in histamine poisoning because of high histidine levels in the muscle. There is high demand for fresh tuna fillet and steaks for Japanese type foods, and as a grilled item in restaurants. Demand for fresh, additive-free and safe seafood products has stimulated efforts to discover novel methods to prolong the shelf life of fresh products with minimum loss of quality. High pressure processing was investigated for its effects on quality and useful shelf life of fresh tuna. Fresh tuna was subjected to various pressure treatments (220 MPa, 200 MPa, 150 MPa), holding times (30 min, 15 min) and temperature (below 20oC). The pressure treated and control (untreated) samples were analyzed for initial physicochemical properties and subsequent changes during chilled storage. Color parameters (L*, a* and b* values), texture, drip loss, pH, sensory attributes, endoprotease activity, TBA, TVB and histamine levels were all evaluated. All the pressure-treated samples lost their glossiness, and their redness decreased with pressure and holding time. Pressure treatment increased yellowness of the samples, and the ‘b’ values increased throughout storage. High pressure processing above 150 MPa resulted in firmer muscles with higher springiness. High pressure also resulted in increased drip loss for all pressure treated samples. However during chilled storage increase in drip loss was significantly faster in untreated samples than in pressure treated samples. Proteolytic activity did not change significantly during storage, unlike the TVB levels that increased during storage. Pressure treatments at 220 MPa/30 or 15 min, and 200 MPa/30 min reduced TVB values the most. None of applied pressure conditions induced major changes in initial pH values. Also no consistent pattern was observed for TBA levels, although the levels were low and indicative of high quality products. Histamine formation was inhibited by pressure treatmentLe thon est fortement périssable et a été impliqué dans l’empoisonnement de l’histamine à cause de niveau très élevé d’histidine dans la chair du poisson. Il y a un forte demande pour le filet de thon frais et de steaks de type japonais de même que les grillades. La demande pour les produits frais de mer, sans additifs et sûrs a stimulé le milieu scientifique afin de découvrir de nouvelles méthodes pour prolonger la durée de vie des produits frais avec la perte minimale de qualité. Le traitement à haute pression a été évalué pour ses effets sur la qualité et la durée de vie du thon frais. Le thon frais a été soumis aux divers traitements de pression (220 MPa, 200 MPa, 150 MPa), avec les temps de rétention de 30 minutes et 15 minutes, et une température sous 20ºC. Les échantillons pressurisés et non pressurisés ont été analysés pour leurs propriétés physicochimiques initiales ainsi que les changements associés au stockage. Les paramètres de couleur (CIE L*, a* et b*), la texture, l’exsudat, pH, les attributs sensoriels, l'activité endo-protéase, TBA, TVB et le niveau d’histamine ont été évalués. Tous les échantillons pressurisés ont perdu leur lustre, et leur rougeur a diminué avec la pression et le temps de rétention. La pressurisation a augmenté le jaune des échantillons et les valeurs de ‘b’ ont augmentés au cours du stockage. Le traitement à haute pression au-dessus de 150 MPa a augmenté la fermeté des muscles ainsi qu’une élasticité plus élevée. Par le fait même, le traitement à haute pression a causé l'augmentation de l’exsudat de tous les échantillons pressurisés. Cependant, l’exsudat était significativement plus rapide sur les échantillons non traités que sur les échantillons pressurisés. L'activité protéolytique n'a pas changé significativement durant le stockage, à la différence des niveaux de TVB qui ont augmenté durant le stockage. La pressurisation à 220 MPa/
23
Lamine, Slim 1965. "A predictive model of shelf life enhancement for meat packed under modified atmospheres". Thesis, The University of Arizona, 1991. http://hdl.handle.net/10150/277920.
Testo completoAbstract (sommario):
A dynamic model of fresh beef packaged under modified atmospheres has been developed. This model links the change in meat color with the permeation of gases (O₂, CO₂, N₂) through the packaging film. Its viability is demonstrated with experimental data using muscle semimembranosus with which it was shown that color change of the meat surface and the change of headspace gas concentration were well described by the model. Moreover, the model parameters were obtained independently of the model itself through the literature. A major result of the model showed that surface color is independent of oxygen concentration above 5%. Moreover, under aseptic conditions and ambient atmosphere concentrations, shelf-life of muscle semimembranosus was shown to be 11 days with this value possibly being a minimum.
24
Orleans, Kimberly Ann. "Microbiological and Chemical Changes During Shelf-life in Regular and Chocolate Milk". The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1308253657.
Testo completo
25
Leek, Viktor. "Reduction of wastage costs for products with short shelf life : A case study on the Swedish division of the global dairy company Arla Foods". Thesis, KTH, Industriell ekonomi och organisation (Inst.), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-98554.
Testo completoAbstract (sommario):
Background – inventory management theory has in the past been focused on traditional engineering industries. These theories are not completely applicable on industries such as FMCG where the main objective is to avoid obsolescence and not tied-up capital. A part of the FMCG industry that is especially pressured by short shelf lives is the food industry. The food industry has also the disadvantage that the customers demand instant deliveries, which makes production to order impossible. Arla Foods is a dairy company that is struggling with high and increasing wastage costs. The wastage cost is generated from products where last sales date is exceeded and Arla Foods CSE therefore has to trash the products even if the best-before date is still valid. These costs need to be reduced on both short and long term. Hence Arla Foods is perfect as a case company for this study. Purpose – the ulterior purpose of this study is to seek if the current theory is applicable on the food industry. This is investigated through a case study at Arla Foods with the following questions asked: Which factors drives wastage costs at a global dairy company such as Arla Foods? How do the factors relate to each other? Which actions could be taken to reduce the wastage costs at a global dairy company such as Arla Foods? To what extent could these findings be generalizable? Method – a thorough literature study is conducted to create an understanding of the existing theories. The case study is mainly based on interviews and observations with employees at Arla Foods. Data has been extracted from internal data bases and processed to complement the interviews and observations. Conclusion – the case company showed that the most significant wastage drivers on an article level were forecast deviations and batch size/delivery frequency. However, the main wastage drivers at Arla Foods were nothing that could be found in neither supply chain management nor inventory management theory – this was instead problems related to work process, organization, communication and strategy. Suggested solutions to these problems are among others: Going through the worst performing articles’ set-up in a structured way. Making sure that there exists a clear process and that all employees are educated in it. Having a back-up plan on what to do with excessive inventory. Using follow-up reports as tools to take action from. When these problems have been solved, Arla Foods can instead focus on planning principles such as taking steps towards a more integrated collaboration with their customers via Efficient Consumer Response. The findings are not proved to be general in any way, but the conclusion of the report still states that there is a high probability that these findings could be applied on other companies within the food industry in general and within the dairy industry in specific. If this is the case, then it is shown that the current theory lacks several aspects when it comes to food industry – aspects that maybe do not have the same importance within most of the traditional engineering industries. Originality – the literature review conducted before the case study did not show any other case study or research that has made an equally broad overview. Earlier studies have mainly been focused on that the food industry is in need of customized planning principles and systems. That research has in the end advocated implementation of Efficient Consumer Response or similar.
26
Goeksoy, E. O. "Decontamination of poultry meat by intense heat treatment". Thesis, University of Bristol, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297810.
Testo completo
27
Khan, Abdulla. "Effects of Processing and Packaging Modifications on the Quality and Shelf Life in Meats". DigitalCommons@USU, 2014. https://digitalcommons.usu.edu/etd/3967.
Testo completoAbstract (sommario):
Shelf life of meat and meat products depends on the quality of meat and packaging stability. Meat color change, lipid oxidation, pH, and microbial contamination are the main causes that affect the nutritional, sensory, and physical characteristics by forming toxic compounds, off flavors, off odors, and undesirable color. The first objective of this study was to examine the effect of newly developed CO2 generating absorbent pads on beef, tuna and chicken meats. The second objective was to compare the effect of Type I (radical quenching) antioxidants eugenol and rosmarinic acid (RA) to that of Type II (metal chelating) antioxidants milk mineral (MM), phytate, and sodium tri-polyphosphate (STPP) in raw ground chicken patties. In the first study samples of beef semitendinosus muscle, boneless and skinless chicken breast, and yellowfin tuna loins were chosen and packaged with four different pad types. Red meats and chicken exhibited trends as would normally be expected during storage. Specifically, color became less appealing (beef and tuna color changed from red to brown, and chicken changed from yellow–pink to grey); pH increased, microbial counts increased, and lipid oxidation (rancidity) increased. Lightness (L*) values for chicken were within 46 – 54, for tuna L* value range was 21-26. Redness/greenness (a*) is an indicator of freshness in red meats, and for beef steaks an average value of 12.32 was noted on day 8, indicative of fresh red color. Recorded average lipid oxidation (TBA values in mg/kg of meat) for chicken (< 0.19 mg/kg) and tuna were low (< 0.16 mg/kg) and for beef (1.06 mg/kg). Even though there was a significant effect of storage time (P < 0.05) as expected, no significant (P >0.05) differences were observed between the four tested pad types over the 8-day testing period.
In study 2, (Chapter 4) a significant antioxidant effect (P < 0.05) was observed in L* values of ground chicken color between treatments. Milk mineral effectively preserved fresh color and slowed lipid oxidation in chicken patties by day 10. Inverse correlations (P < 0.001) were observed between pH (increasing), and lightness, redness values (decreasing) from day 1 through 10. Increased pH levels from slightly acidic to basic or physiological pH resulted in high numbers for total aerobic plate-counts. There was a significant antioxidant effect on lipid oxidation values by day 10; eugenol and MM were more effective (P < 0.05) than STPP in controlling lipid oxidation measured as thiobarbituric acid reactive substances (0.198 mg/kg, 0.198 mg/kg, and 0.268 mg/kg, respectively). In conclusion, CO2 generating absorbent pads did not have a positive effect on meat quality, while the antioxidant milk mineral efficiently maintained color, and pH, and controlled lipid oxidation and limited the growth of aerobic bacteria when compared to other antioxidants.
28
De, Luca Paola. "L'importanza dell'Atmosfera Modificata nel Confezionamento di Frutta e Verdura Minimamente Processate". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/19261/.
Testo completoAbstract (sommario):
L’atmosfera modificata è una tecnologia all’avanguardia che permette di allungare la conservazione (shelf-life) di alimenti freschi e deperibili anche di alcune settimane al fine di assicurare al consumatore frutta e verdura fresca durante tutto l’anno, sia quella continentale sia quella extra continentale. Per permettere tutto ciò bisogna studiare a fondo la miscela ottimale di gas per ogni alimento tenendo conto di numerose variabili come gli effetti che CO2 ed O2 hanno sul prodotto, la solubilità dei gas nel cibo, la respirazione dei frutti, le attività microbiche e fungine. La tesi si occupa in particolare di “minimally processed foods”, ovvero di quegli alimenti che hanno subito una lavorazione blanda come ad esempio lavaggio, taglio, triturazione, rimozione delle foglie ecc. Dal punto di vista nutrizionale conservano ancora le loro caratteristiche in quando non sono stati sottoposti a trattamenti invasivi con calore o congelamento. Per questo motivo è importante il mantenimento della loro qualità attraverso il MAP (modified atmosphere packaging), all’interno di pellicole polimeriche adeguate ed a temperature di refrigerazione.
È una sfida molto interessante per i tecnologi alimentari, soprattutto in un mondo in cui il consumatore esige sempre più reperibilità e qualità dei prodotti, con caratteristiche intrinseche sempre più rilevanti quali la salvaguardia dell’ambiente, l’ecologia, la biodegradabilità e la tutela degli animali. Negli ultimi periodi si stanno sviluppando studi nel campo del packaging commestibile proprio per venire incontro a queste esigenze sempre più forti che sono determinanti sull’acquisto di un prodotto o meno. I rivestimenti commestibili offrono numerosi vantaggi anche in termini di praticità, ad esempio proteggono frutta e verdura contro lividi e danni ai tessuti causati da urti e vibrazioni e offrono anche una barriera contro l’ossigeno.
29
Liu, Jiun Ni 1976. "Formulation, shelf-life and safety studies on value-added trout products packaged under modified atmospheres". Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=30690.
Testo completoAbstract (sommario):
Value-added trout burgers and trout wontons were prepared from minced trout trimmings, oats, dried onion flakes, white pepper, cayenne pepper, garlic powder, soy sauce, spice mix and eggs. The trout burgers were coated with crushed cornflakes and then partially cooked (2 min at 140ºC) or frilly cooked (5 min at 140ºC) in hot oil. Similar fillings were used to prepare trout wontons by wrapping the mixture with Chinese wonton dough and 2 products were made: raw wonton (uncooked) and fried wonton (fried for 8 min at 140ºC).Storage trials were performed on raw and fried trout wontons (a w 0.98--0.95, pH 6.5), and partially and fully cooked trout burgers (aw 0.97--0.96, pH 6.4). Products were packaged in air and under various modified atmospheres (MAP), and stored at 4 and 12ºC. A microbiological shelf-life of >28 days was possible for the cooked trout burgers and fried wontons stored at 4ºC. In general, the microbiological shelf-life preceded the sensory shelf-life.
Subsequent challenge studies were done to address the safety concerns associated with MAP food. All products were inoculated with 102 CFU/g of Listeria monocytogenes and 102 spores/g of Clostridium botulinum type E spores. Gas packaging with 80% CO2 (balance N2) inhibited the growth of L. monocytogenes in products stored at 4ºC. However, counts of L. monocytogenes increased in all other packaging conditions. In challenge studies with C. botulinum type E, toxin was not detected in any products after 28--60 days.
30
Badiger, Aishwarya Satish. "Consumer Food Waste Reduction using Dynamic Labelling and Predictive Shelf-life Modelling for Pasteurized Milk". The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1532015322705163.
Testo completo
31
Chien, Yung-hsin. "SHELF LIFE EXTENSION OF SEED BUTTER MADE WITH SESAME, SUNFLOWER AND PUMPKIN SEEDS". The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1449235219.
Testo completo
32
Padmanabhan, Natarajan. "A novel mechanism for delivering nutrition: sorghum based fortified blended foods using extrusion". Thesis, Kansas State University, 2013. http://hdl.handle.net/2097/16302.
Testo completoAbstract (sommario):
Master of ScienceDepartment of Grain Science and Industry
Sajid Alavi
The objective of the study was to investigate extrusion as an alternative processing method and grain sorghum as a viable substitute for corn in fortified blended foods (FBFs) used in nutrition and food assistance programs around the world. In the first part of this study, sorghum-soy blend (SSB), corn-soy blend (CSB) and whole corn-soy blend (WCSB) were developed using extrusion and compared with traditional CSB13 for physico-chemical and sensory properties. After milling of extrudates, average particle size (PS) ranged between 341-447 microns, with 78-85% below 600 microns. In general, Bostwick flow rates (VB=12-23 cm/min) of rehydrated blends (11.75% solids) were within standard specifications but higher than CSB13. Descriptive sensory analysis indicated that the sorghum-based rehydrated blends were significantly less lumpy and had a more uniform texture as compared to corn-based blends and CSB13. In the second part, the impact of decortication level and process conditions was investigated with respect to sorghum-based extruded blends. Degree of gelatinization of the whole sorghum-soy blend (WSSB) and decorticated sorghum-soy blend (DSSB) extrudates ranged from 93-97%. Expansion ratio (ER=3.6-6.1) was correlated with specific mechanical energy input (SME=145-415 kJ/kg; r=0.99) and average particle size after milling (PS=336-474 microns; r= -0.75). Rehydrated blends at 20% solids concentration provided recommended energy density (0.8 kcal/g) for FBFs. Bostwick flow rates had high correlation (r = -0.91) with pasting data (final viscosity) obtained using rapid visco analyzer (RVA). Addition of oil (5.5%) prior to extrusion was also studied, and resulted in process instabilities and also lower shelf-life as determined via descriptive sensory analysis (rancid and painty attributes) and gas chromatography-mass spectroscopy (hexanal, heptenal and octanal concentrations). In conclusion, extruded sorghum-soy blends met standard specifications for energy density and consistency (Bostwick flow rate), and were superior in some aspects as compared to extruded corn-soy blends and traditional corn-soy blends (CSB13). Relationships between extrusion mechanical energy input, expansion, particle size after milling and consistency of rehydrated blends were established. Consistency of the rehydrated blends is an extremely important criterion as it affects the ease of ingestion by target consumers (children below 5 years, in this case).
33
Hadawey, Abas. "Design of chilled food display cabinets for better temperature integrity and longer product shelf life". Thesis, Brunel University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436477.
Testo completo
34
Cetin-Karaca, Hayriye. "ANTIMICROBIAL EFFICACY OF NATURAL BIOACTIVE COMPOUNDS AND HIGH PRESSURE PROCESSING AGAINST POTENTIAL PATHOGENS IN INFANT FOODS". UKnowledge, 2015. http://uknowledge.uky.edu/animalsci_etds/57.
Testo completoAbstract (sommario):
This study investigated the antimicrobial efficacy of bioactive plant compounds along with high pressure processing (HPP) against pathogens Bacillus cereus and Cronobacter sakazakii in infant formula and infant rice cereal. The influence of these applications on antimicrobial activity, shelf-life and sensory attributes of infant foods were examined.
Trans-cinnamaldehyde (TC), (-)-Epigallocatechin gallate (EGCG) and [10]-Gingerol (GI) were incorporated (0.05%) in infant rice cereal reconstituted with infant formula. The cereal was inoculated with either B. cereus (ATCC 14579) or B. cereus spores (107-108 log CFU g-1). All the samples were stored at 7, 23 or 37°C for 0, 4, 8 and 24 h. TC showed the highest antimicrobial activity by inhibiting the B. cereus and its spores up to 2.72 and 3.8 log CFU g-1, respectively.
HPP (600 MPa for 5 m), and TC (0.05-0.1%) along with Chitosan (CH) (1%), were applied to reconstituted powder infant formula which was inoculated with either 3 strains of C. sakazakii (ATCC 29544, ATCC 12868, and ATCC BAA 894) or 5 strains of B. cereus spore (ATCC 14579, ATCC 33018, ATCC 12826, ATCC 4342, and Difco Spores) cocktail (107-108 log CFU ml-1). All the samples were stored at 7, 23 or 45°C for 5-8 weeks. HPP and TC (0.1%) combination exhibited the highest inhibition (P < 0.05) by reducing the B. cereus spores 2.97 log CFU ml-1 after 7 d. C. sakazakii was fully inactivated by HPP, TC (0.05%) and C (1%) combination following 8 weeks of storage at 7 and 23°C and 2 weeks storage at 45°C. The combination of HPP and bioactive compounds exhibited additive antimicrobial effect.
Gradual decrease (P < 0.05) in pH was observed in rice cereal and non-HPP formula samples due to the microbial growth and metabolic activity. Significant differences (P < 0.05) were found in color, aroma and general appearance of EGCG and GI applied cereal samples, while TC only did exhibit a cinnamon taste.
In summary, the antimicrobial findings suggest that TC, EGCG, GI and CH could be incorporated in infant foods along with HPP as natural and safe alternatives to synthetic preservatives and thermal applications.
35
Nagalingam, Thevaki. "The application of combined preservation techniques to maintain the quality and extend the shelf life of avocado". Thesis, University of Reading, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332005.
Testo completo
36
Leygonie, Coleen. "Evaluation of packaging and freezing and thawing rates on the shelf-life stability of ostrich meat". Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/18116.
Testo completoAbstract (sommario):
Thesis (PhD (Food Sc))--Stellenbosch University, 2011.ENGLISH ABSTRACT: Ostrich meat has become increasingly popular in South Africa and abroad, driven by the health conscious trend and ostrich meat’s natural low intramuscular fat, high polyunsaturated fatty acid and low cholesterol content. This increased demand led to the investigation of novel packaging regimes to improve its attractiveness and shelf-life. Different modified atmospheric packaging regimes were studied for fresh and frozenthawed ostrich M.iIliofibularis steaks stored at ±4°C for 10 days. Oxygen MAP (30 CO2:70 O2) was applied with great success to fresh steaks, and resulted in significantly improved colour stability, decreased drip loss and a 10-day shelf-life. Oxygen MAP of frozen-thawed ostrich steaks was not successful as the colour deteriorated within 3 days, coupled with high lipid and protein oxidation. The microbial shelf-life was not influenced by freezing and thawing. The use of nitrogen MAP (30 CO2:70 N2) as an alternative to vacuum packaging for fresh and frozen-thawed ostrich meat was inconclusive due to trace amounts of residual oxygen in the headspace accelerating myoglobin oxidation by depleting the metmyoglobin reducing activity. The differences in oxidative stability of the fresh and frozen-thawed ostrich meat led to the investigation of the source of these differences and a system that would allow control over the freezing and thawing practice. This was supported by the industry that is under increasing pressure to reduce the excessive (15-20%) thaw weight loss that is continually reported. Subsequently, a mathematical prediction model based on the control volume approach was developed that predicted the rate of freezing and thawing of intact whole vacuum-packed ostrich muscle. The model predicted with greater accuracy than existing models, and can be used successfully by the industry to optimally design, control and operate their systems. Furthermore research was conducted to investigate the effect of different freezing and thawing rates on the ice crystal formation and the quality of ostrich M. femorotibialis stored at ±4°C post freeze/thaw. Five characteristic freezing rates (FR (time from 0°C to -7°C): 1, 2, 4, 8, 24h) were paired with five characteristic thawing rates (TR (time form -7°C to 0°C): 1.5, 3, 6.5, 14, 21h) in a completely randomised block design. Results showed that thawing had no impact on any of the tested quality parameters, including thaw loss. Freezing rate however did influence the ice crystal formation and at a characteristic freezing rate of one hour (FR_1h) only intracellular ice crystals were observed throughout the M. femorotibialis leading to the lowest thaw loss (2.57%) and highest shear force. Freezing rate of 2h, 4h and 8h (FR_2h, FR_4h and FR_8h) were dominated by extracellular ice crystals. FR_2h and FR_8h showed major dehydration of the muscle fibres and excessive distortion of the muscle fibre matrix that led to significantly lower oxidative stability. FR_24h (approximately commercial rates) formed columns of ice from the surface to the centre of the meat resulting in the highest thaw loss (6.24%). FR_4h was judged to deliver the best quality product with moderate thaw (3.93%) and drip loss, low cooking loss, good colour stability and extremely low TBARS. FR_4h is an achievable rate of freezing for the industry and if implemented should decrease the thaw loss problem as well as increase revenue and throughput in the processing facility.
AFRIKAANSE OPSOMMING: ‘n Hedendaagse strewe na ‘n gesonde lewenstyl tesame met die natuurlike lae vetinhoud (d.i. hoë poli-onversadigde vetsure en lae cholesterolvlak) van volstruisvleis het gelei tot ‘n toename in die nasionale en internasionale aanvraag. Hierdie het ook die behoefte laat ontstaan om nuwe verpakkingstegnieke te ondersoek om sodoende die aanvaarbaarheid en rakleeftyd van die produk te verleng. Die invloed van verskeie gewysigde atmosferiese verpakkingsmetodes (GAV) op die kleurstabiliteit, drupverlies en rakleeftyd van vars en bevrore/ontdooide volstruisvleis (spesifiek M. Iliofibularis), gestoor by ±4°C vir 10 dae, is ondersoek. Die suurstof GAV (30 CO2:70 O2) van vars volstruisvleis het ‘n verbetering in kleurstabiliteit, verlaagde drupverlies en 'n verlengde mikrobiese rakleeftyd (10 dae) tot gevolg gehad. Die suurstof GAV van bevrore-ontdooide volstruisvleis het geen voordelige effek op kleurstabiliteit en rakleeftyd getoon nie. Die bevrore/ontdooide monsters het totaal verkleur na 3 dae en ‘n hoë vlak van lipied- en proteïenoksidasie is waargeneem. Die bevriesing en ontdooiing het geen invloed op rakleeftyd gehad nie. Die moontlikheid om stikstof GAV (30 CO2:70 N2) as 'n alternatief tot vakuumverpakking vir vars en bevrore/ontdooide volstruisvleis te gebruik, is beïnvloed deur die teenwoordigheid van oorblywende suurstof in die lugruimte van die GAV, met ‘n gevolglike toename in die tempo van mioglobien oksidasie as gevolg van ‘n afname in die metmioglobien reduksie aktiwiteit. Die verskil in die oksidatiewe stabiliteit van vars en bevrore/ontdooide volstruisvleis het gelei tot ‘n verdere ondersoek na die oorsaak van die verskille en die ontwikkeling van ‘n moontlike protokol om die oksidatiewe stabiliteit en dus rakleeftyd van volstruisvleis, te verbeter en bestuur. Die behoefte aan so ‘n protokol is beklemtoon deur die bedryf wat onder toenemende druk verkeer om buitensporige ontdooiingsverliese (15-20%) te verminder. ‘n Wiskundige voorspellingsmodel, gebaseer op die beheer-volume benadering, is ontwikkel om die tempo van bevriesing en ontdooiing van vakuumverpakte heel volstruisspiere te voorspel. Die model het tempo van bevriesing en ontdooiing met groter akkuraatheid as die bestaande modelle voorspel en kan suksesvol gebruik word in die bestuur van slagpale. Verder navorsing is onderneem om ondersoek in te stel na die effek van die tempo van bevriesing en ontdooiing op die kwaliteit van die bevrore-ontdooide volstruisvleis tydens berging by ±4°C. Die invloed van die kombinasie van vyf bevriesingstempo’s (FR (tydsverloop 0°C tot -7°C): 1, 2, 4, 8, 24 h) met vyf ontdooiingstempo’s (OT (tydsverloop -7°C to 0°C): 1.5, 3, 6.5, 14, 21 h) is ondersoek. Die resultate het getoon dat ontdooiingstempo geen beduidende invloed op enige van die kwaliteit kriteria, insluitend ontdooiingsverlies, gehad het nie. Bevriesingtempo het egter ‘n groot rol ten opsigte van yskristalvorming gespeel. Teen ‘n kenmerkende bevriesingstempo van een uur (FR_1h) was slegs intrasellulêre yskristalle waargeneem dwarsdeur die M. femorotibialis wat gelei het tot die laagste ontdooiingsverlies (2.57 %). Die ander bevriesingstempo’s, d.i. FR_2h, FR_4h en FR_8h, het gelei tot die vorming van meestal ekstrasellulêre yskristalle. Bevriesingstempo’s van FR_2h en FR_8h het beduidende dehidrasie van die spiervesels en vervorming van die spiervesel matriks tot gevolg gehad, wat tot verhoogde oksidasie gelei het. ‘n Bevriesingstempo van FR_24h (d.i. kommersieële tempo), het gelei tot die vorming van yskolomme van die oppervlak na die middelpunt van die spier, wat gevolglik die grootste ontdooiingsverlies (6.24%) tot gevolg gehad het. ‘n Bevriesingstempo van vier ure (FR_4h) is bestempel as die mees geskikte bevriesings tempo as gevolg van ‘n matige ontdooiingsverlies (3.93%), drupverlies, lae kookverlies, goeie kleur stabiliteit en uiters lae lipiedoksidasie te verseker. Die FR_4h bevriesingstempo is haalbare in die bedryf. Indien dit geïmplementeer word, sal dit waarskynlik die deurset van die slagpalesiklus asook die kostedoeltreffendheid van die volstruisbedryf vebeter, deur die vermindering van ontdooiingsverlies en verbetering van die algehele kwalitiet van die vleis.
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Steele, Kyle Stover. "Shelf life of five meat products displayed under light emitting diode or fluorescent lighting". Thesis, Kansas State University, 2011. http://hdl.handle.net/2097/13135.
Testo completoAbstract (sommario):
Master of ScienceDepartment of Animal Sciences and Industry
Elizabeth A. E. Boyle
Light emitting diode (LED) and fluorescent (FLS) lighting effects on enhanced pork loin chops, beef longissimus dorsi and semimembranosus steaks, ground beef, and ground turkey displayed in two retail display cases set up with similar operational temperatures were evaluated using visual and instrumental color, Enterobacteriaceae (EB) and aerobic plate counts (APC), internal product and case temperatures, and thiobarbituric acid reactive substances (TBARS). Visual discoloration of the five meat products increased (P<0.05) as display time increased. Beef longissimus dorsi steaks, ground beef, and the superficial portion of beef semimembranosus steaks had less (P<0.05) visual discoloration under LED lighting than FLS. Compared to FLS, pork loin chops under LED lighting had higher (P<0.05) L* values and a lower (P<0.05) a/b ratio. The deep portion semimembranosus steak under LED was redder (P<0.05) and the superficial portion had a lower (P<0.05) a/b ratio; LED deep and superficial portion semimembranosus steaks had higher (P<0.05) saturation index values at 5.18 and 4.47, respectively, on d 0 than FLS. Pork chops under LED lighting had lower (P<0.05) APC populations than FLS by the end of display. Enterobacteriaceae populations fluctuated throughout display on ground turkey under FLS lighting while populations remained stable under LED. APC populations increased as display time increased for pork loin chops, ground beef and ground turkey, but not beef longissimus dorsi steaks possibly due to initial case-ready postmortem age. As display time increased, EB populations increased (P<0.05) for pork loin chops, ground beef and ground turkey. The internal temperature of all products, except beef longissimus dorsi steaks, was lower (P<0.05) in the LED case. FLS case temperatures were higher (P<0.05) by 0.56 to 1.11°C than LED over the duration of the study. Pork loin chops, ground turkey, and beef semimembranosus steaks had higher (P<0.05) TBARS values by 0.06 to 0.24 mg malonaldehyde/kg under LED lighting, but lighting type did not affect (P>0.05) lipid oxidation of beef longissimus dorsi steaks or ground beef. LED lighting results in lower display case temperatures, lower internal product temperatures, and extended color life; however, lipid oxidation was increased in some cuts under LED lighting.
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Chen, Ruiji. "The effect of modified atmosphere packaging and methyl jasmonate on the shelf life of lychee". The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1563501432071153.
Testo completo
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Engelbrecht, Sanneliza. "Microbial content stability and inhibitory effects of antimicrobials on the shelf-life of high moisture dried fruit". Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51828.
Testo completoAbstract (sommario):
Thesis (MSc Food Sc )--Stellenbosch University, 2000.ENGLISH ABSTRACT: Drying of fruit is an age-old preservation technique that even to this day, remains popular. On the foreign markets there is a trend towards dried fruit products that are softer and more palatable. Based on this, the South African dried fruit industry has launched a range of "soft eating", high moisture dried fruit (HMOF) products. These products have a moisture content of ca 36% (w/w) and a water activity (aw) of ca 0.85, both of which are considerably higher than that of traditional dried fruit. It is this higher moisture content that makes the product susceptible to serious microbial spoilage and colour deterioration in spite of the use of sulphur dioxide. Currently, the shelf-life of these products is approximately three months and to ensure a quality export product, the shelf-life must be at least nine months. During this study the microbial composition of five South African commercially available HMDF products (raisins, prunes, nectarines, cling stone peaches and apricots), was determined. It was found that high moisture dried (HMO) raisins and prunes had the highest bacterial counts, while apricots were more susceptible to yeast and mould spoilage. The most frequently isolated microbes were members of the endospore forming Bacillus group and osmotolerant yeasts like Zygosaccharomyces. Members of the genera Salmonella, Staphylococcus and even anaerobic endospore formers were present in certain samples of the HMO prunes and raisins. From these results it was concluded that the current pasteurisation method of 7 h at 80°C used by the industry is not effective in successfully eliminating spoilage microbes. High moisture dried nectarines and prunes were used in challenging studies, where four indicator organisms (B. cereus, Z. rouxii, Escherichia coli and Penicillium chrysogenum) were selected to evaluate the shelf-stability of these two HMOF products over six months at 5° and 25°C. The results showed higher bacterial counts for the fruit stored at 25°C (1 200 cfu.g ̄ ¹ versus 450 cfu.g ̄ ¹ at 5°C), as well as extensive Maillard browning of the nectarines at the higher storage temperature. Furthermore, it was found that the pasteurisation method (7 h at 80°C) was not effective in eliminating the endospore former B. cereus, P. chrysogenum and Z. rouxii, which may thus lead to serious spoilage implications. The E. coli strain did not survive in either of the HMOF products and no counts were found even before pasteurisation. From these results it was clear that the current pasteurisation method of HMOF products is not effective in terms of the prevention of spoilage, and that storage of the product at lower temperatures would lead to a better quality product. The impact of different preservatives (lysozyme, pimaricin, sorbate, benzoate and an imidazole compound) on the survival and growth of B. cereus and Z. rouxii, were evaluated in nectarine puree prepared from dried nectarines. Lysozyme showed the best inhibitory effect (70% inhibition) on B. cereus over a 12 h incubation period, followed by benzoate, sorbate, the imidazole compound and lastly, pimaricin. The data obtained for the inhibitory effect of the preservatives on Z. rouxii showed that benzoate and sorbate showed. the best growth inhibitory effect (100% inhibition after 24 h). Pimaricin gave a 100% inhibitory effect after 48 h while the imidazole compound gave a 89% inhibition. From the different pasteurisation time/temperature combinations applied to eliminate the endopspore former B. 'cereus, it was found that pasteurisation of 150 min at 90°C showed the best inhibition results. However, the colour of the product was unstable. It was, therefore, decided to also evaluate the use of modified atmosphere packaging (MAP), as part of the product's processing. It was found that the colour of the HMO nectarines was stable and it is thus recommended that a time/temperature combination of 150 min at 90°C together with MAP, is used to ensure a shelf-stable HMOF product.
AFRIKAANSE OPSOMMING: Die droging van vrugte is 'n eeu-oue preserveringstegniek wat vandag steeds baie gewild is. Daar is 'n tendens in die oorsese markte na droëvrugte wat sagter en smaakliker is. Gebaseer op hierdie tendens het die Suid Afrikaanse droëvrugtebedryf 'n nuwe "soft eating", hoë vog droëvrug (HVDV) produkreeks die lig laat sien. Hierdie produkte het 'n voginhoud van ca 36% (m/m) en 'n water aktiwiteit (aw) van ca 0.85. Dit is die hoër voginhoud wat lei tot mikrobiologiese bederf en verbruining. Tans is die rakleeftyd van die produkte ongeveer drie maande, terwyl uitvoer standaarde 'n rakleeftyd van minstens nege maande vereis. Tydens hierdie studie is die mikrobiese samestelling van vyf Suid Afrikaans beskikbare HVDV produkte (rosyne, pruimedante, nektariens, taaipit perskes en appelkose) bepaal. Dit is bevind dat hoë vog droë (HVD) rosyne en pruimedante meestal hoë bakterie tellings het, terwyl appelkose meer vatbaar is vir giste en misiliêre fungi. Die organismes wat meestal geïsoleer is, was lede van die endospoorvormende Bacillus groep en osmotolerante giste soos Zygosaccharomyces. Lede van die genera Salmonella, Staphylococcus en selfs anaerobiese endospoorvormers is gevind in van die HVD pruimedante en rosyne. Vanuit hierdie resultate was dit duidelik dat die huidige pasteurisasie proses van 7 h by 80°C, wat deur die industrie gebruik word, nie effektief is om bederf organismes suksesvol te elimineer nie. Hoë vog droë nektariens an pruimedante is gebruik in uitdaging studies, waar vier indikator organismes (B. cereus, Z. rouxii, Escherichia coli en Penicillium chrysogenum) gekies is, om die rakleeftyd van die twee HVDV produkte oor 'n opbergingstydperk van 6 maande by 5° en 25°C te evalueer. Die resultate het hoër bakteriese tellings vir vrugte wat by 25°C (1 200 kve.g ̄ ¹ versus 450 kve.g ̄ ¹ by 5°C) opgeberg is getoon, asook dat Maillard verbruining by HVD nektariens plaasvind by die hoër opbergingstemperatuur. Verder is bevind dat die pasteurisasie metode (7 h by 80°C) nie effektief was om die endospoorevormer B. cereus, P. chrysogenum en Z. rouxii te elimineer nie, wat ernstige bederf implikasies tot gevolg kan hê. Die E. coli stam het nie in een van die twee HVDV produkte oorleef nie en geen tellings is gevind nie, selfs nie voor pasteurisasie nie. Die resultate het duidelik getoon dat die huidige pasteurisasie proses vir HVDV nie effektief is om mikrobiese bederf te voorkom nie, terwyl 'n lae opbergingstemperatuur aanbeveel word om 'n beter kwaliteit eindproduk te verseker. Die impak van verskillende preserveermiddels (lisosiem, pimarisien, sorbaat, bensoaat en 'n imidasool verbinding) ten opsigte van die groei en oorlewing van B. cereus en Z. rouxii is geëvalueer in nektarien puree. Lisosiem het die beste inhibisie effek (70% inhibisie) t.o.v. B. cereus getoon gedurende die 12 h inkubasie periode, gevolg deur bensoaat, sorbaat, die imidasool verbinding en laastens pimarisien. Die data verkry vir die inhibitoriese effek van die preserveermiddels t.o.v Z. rouxii, het getoon dat bensoaat en sorbaat die beste groei inhibisie getoon het (100% inhibisie na 24 h). Pimarisien het 'n 100% inhibisie getoon na 48 h, terwyl die imidasool verbinding 89% inhibisie getoon het. Van die verskillende pasteurisasie kombinasies wat aangewend is om die endopsoorvormer B. cereus te elimineer, is dit bevind dat 'n pasteurisasie van 150 min by 900G die beste inhibisie resultate getoon het. Die kleur van die nektariens was egter onstabiel. Gevolglik is daar besluit om gemodifiseerde atmosfeer verpakking (MAV) te evalueer as deel van die produk se prosessering. Dit is bevind dat die kleur van die HVD nektariens stabiel was en daar word verder aanbeveel om 'n tyd/temperatuur kombinasie van 150 min by 90°C, saam met MAV te gebruik, om 'n kwaliteit eindproduk te verseker.
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Hussein, Zaharan. "Perforation-mediated modified atmosphere packaging (PM-MAP) and shelf-life of pomegranate fruit arils (cv. ACCO)". Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/96079.
Testo completoAbstract (sommario):
Thesis (MScFoodSc)--Stellenbosch University, 2014.ENGLISH ABSTRACT: Perforation-mediated modified atmosphere packaging (PM-MAP) offers the possibility of optimising polymeric films in order to compensate for barrier limitations of conventional modified atmosphere packaging (MAP). The aim of this study was to investigate the effects of PM-MAP and storage duration on the physico-chemical quality attributes, microbial quality, phytochemicals (anthocyanins, phenolics and ascorbic acid) and antioxidant activities of arils from fresh minimally processed pomegranate (cv. Acco). The effects of number of perforations (0, 3, 6 and 9; Ø = 0.8 mm) and storage temperature (5, 10 and 15 ºC) on water vapour transmission rate (WVTR, g/m2.day) of synthetic ‘Polylid’ and biodegradable (Nature flexTM) polymeric films were investigated. The results showed that non-perforated biodegradable film had higher WVTR at all storage temperatures, and irrespective of film type, increasing the number of perforations (from P-3 to P-9) had higher impact on WVTR than increasing storage temperature (from 5 to 15 ºC). Furthermore, this study investigated the effects of PM-MAP on the physico-chemical properties, phytochemicals components and antioxidant activities of fresh minimally processed arils. Arils (100 g) were packaged in polypropylene trays (10.6 x 15.1 cm2) and heat-sealed with a polymeric film POLYLID®. Perforations (0, 3, 6 and 9; Ø = 0.8 mm) were made on the top of the film and all samples were stored at 5 ± 1 ºC and 95 ± 2% relative humidity for 14 days. Samples were analysed at intervals of 3, 6, 9, 12 and 15 days. Microbial analysis included tests for Escherichia coli, aerobic mesophilic bacteria, yeast and moulds at days 0, 6, 10 and 14. The results showed that headspace gas composition was significantly influenced by the number of perforations, which helped balance the decrease in O2 with corresponding increase in CO2 levels, thus preventing anoxic conditions. Total soluble solids, titratable acidity and firmness of arils were slightly reduced by PM-MAP compared to clamshell trays. Colour attributes was generally maintained across all treatments and throughout the storage duration. The highest counts of aerobic mesophilic bacteria (5.5 log CFU/g), yeast and moulds (5.3 log CFU/g) were observed in P-0 and P-9 packages, respectively. Overall, P-3 and P-6 better maintained the physico-chemical properties and microbial quality of arils. Total phenolics and anthocyanin contents were higher in arils packaged in PM-MAP while ascorbic acid was slightly reduced. Antioxidant activities tested against FRAP and DPPH radical-scavenging activity increased across all types of MAP over storage duration. However, antioxidant activities were significantly higher in pomegranate arils packaged in PM-MAP due to O2-promoted biosynthesis of phenolics and anthocyanins which constitute the antioxidant properties. Overall, the results reported in this study showed that the use of PM-MAP in cold chain could be suitable for the preservation of physico-chemical quality, phytochemical contents and antioxidant properties of arils packaged in passive PM-MAP compared to clamshell and non-perforated packages during postharvest handling and storage. Perforating MAP films showed potential in preventing the incidence of in-package moisture condensation which is a common problem during postharvest handling and storage of fresh produce packaged inside non-perforated MAP. The results also showed the importance of keeping PM-MAP packs in closed refrigerated shelves to avoid cross contamination or ingress of foodborne pathogens.
AFRIKAANSE OPSOMMING: Perforasie-bemiddelde gewysigde-verpakking (PM-MAP) maak dit moontlik om polimeer films te optimiseer en om sodoende te kompenseer vir die versperring beperkings van die konvensioneel-gewysigde atmosfeer verpakking (MAP). Die doelwit is om die effek van PM-MAP en die duur van stoor op die fisioko-chemiese gehalte kenmerke, mikrobiale gehalte, fitochemikale (antisianien, fenolies en askorbiensuur) en antioksidant aktiwiteite van granaatarils van vars, minimaal geprosesseerde granate, te ondersoek (cv. Acco). Die effek van die aantal perforasies (0, 3, 6 en 9; Ø =0.8 mm) en stoortemperatuur (5, 10 en 15 ºC) op die waterdamp transmissie koers (WVTR, g/m2.day) van sintetiese ‘Polylid’ en biodegradeerbare (Nature flexTM) polymeriese films is ondersoek. Die resultate het bewys dat nie-perforeerde biodegradeerbare film by alle stoortemperature ’n hoër WVTR het, en dat by alle tipes film, ’n verhoogde aantal perforasies (van P-3 tot P-9) ’n hoër impak op WVTR het as ’n verhoogde stoortemperatuur (van 5 tot 15 ºC). Verder is die effek van PM-MAP op die fisiko-chemiese kenmerke, fitochemikale komponente en antioksidant aktiwiteite van vars, minimaal-geprosesseerde granaatarils bestudeer. Die granaatarils (100 g) is verpak in in polipropilien (PP) platkissies (10.6 x 15.1 cm2) en verseël met polimeer film, POLYLID®. Perforasies (0, 3, 6 en 9; Ø =0.8 mm) is aan die bo-end van die film aangebring en alle voorbeelde is vir 14 dae teen 5 ± 1 ºC en 95 ± 2 % relatiewe humiditeit. Die voorbeelde is met tussenposes van 3, 6, 9, 12 en 15 dae ontleed. Die ontleding het toetse vir Escherichia coli, aerobiese mesofiliese bakterië, suurdeeg en skimmel op tussernposes van 0, 6, 10 en 14 dae ingesluit. Die resultate bewys dat die komposisie van die gas beïnvloed word deur die aantal perforasies. Dit help om die vermindering in O2 met ’n ooreenkomstige toename in CO2 vlakke te balanseer en om dus toestande wat deur ’n gebrek aan suurstof veroorsaak is, te verhoed. Die totaal van oplosbare vaste stowwe, titreerbare suurgehalte en fermheid van die granaatarils is deur die PM-MAP verminder veral as dit vergelyk word met “clamshell trays”. Die kleur kenmerke het oor die algemeen dieselfde gebly by al die behandelings en dwarsdeur die stoortydperk. Die hoogste aantal aerobiese mesofiliese bakterië (5.5 log CFU/g), gis en skimmel (5.3 log CFU/g) is in die P-0 en P-9 verpakkings onderskeidelik opgemerk. Oor die algemeen is P-3 en P-6 beter in staat om die fisioko-chemiese kenmerke en mikrobiale gehalte van die granaatarils te behou. Die totaal van die fenoliese and antosianiin inhoud was hoër in granaatarils wat verpak is in PM-MAP maar die askorbiensuur was effens laer. Antioksdant aktiwiteite is getoets teen FRAP en DPPH aktiwiteite het by al die tipes van MAP tydens stoor vermeerder. Antioksidant aktiwiteite was egter heelwat hoër in granate wat in PM-MAP verpak is. Dit is die gevolg van die biosintese van fenolies en antosianins wat deur O2 in die hand gewerk word en wat die basis van antioksidant kenmerke vorm. Oor die algemeen toon die resultate van hierdie studie dat die gebruik van PM-MAP in die koue ketting geskik is vir die behoud van fisieko-chemiese gehalte, fitochemiese inhoud en antioksidant kenmerke van granaatarils wat in passiewe MAP verpak is, veral as dit vergelyk word met die vrugte wat in ‘clamshell’ en nie-geperforeerde verpakking tydens hantering na die oes en tydens stoor verpak is. Die perforeer van MAP films kan die voorkoms van die kondensasie in die verpakking verminder. Hierdie kondensasie is ’n algemene probleem tydens die hantering en stoor van vars vrugte wat in MAP sonder gaatjies verpak is. Die resultate toon ook hoe belangrik dit is om die PM-MAP verpakking in toe, verkoelde rakke te hou en om sodoende kruis-kontaminasie asook kontaminasie deur kieme wat in vrugte teenwoordig is, te voorkom.
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Lee, Yun-ae. "Combined use of modified atmosphere packaging (MAP) and glucose (GOX) for shelf-life extension of fresh fish". Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59900.
Testo completoAbstract (sommario):
The fish processing industry is actively seeking for alternative methods of shelf life preservation and marketability of fresh fish, while at the same time economizing on energy costs. Two methods which fulfill both objectives are modified atmosphere packaging (MAP) and glucose oxidase (GOX)/Glucose dipping solutions. MAP is the packaging of perishable products in an atmosphere other than that of air and is used for the shelf life extension of beef, pork, fruits, vegetables and bakery products. GOX, either alone or in conjunction with MAP has the potential for shelf life extension of fresh fish.The objectives of this study were to determine the combined effect of glucose oxidase/glucose or gluconic acid dipping solutions and modified atmosphere packaging in conjunction with refrigeration on the shelf life extension of mackerel and cod.
This study has shown that the shelf life of fresh fish can be extended through the combined use of MAP/dipping solutions and refrigeration. This novel process of "dipping" in GOX solution in conjunction with modified atmosphere packaging (MAP) will have a significant effect in the area of fish hygiene and will minimize fish losses incurred through spoilage.
42
Verardo, Vito <1977>. "Determination of bioactive and potentially toxic compounds in food: raw material analysis and shelf life evaluation". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1521/.
Testo completoAbstract (sommario):
"Bioactive compounds" are extranutritional constituents that typically occur in small
quantities in food. They are being intensively studied to evaluate their effects on health.
Bioactive compounds include both water soluble compounds, such as phenolics, and lipidic
substances such as n-3 fatty acids, tocopherols and sterols.
Phenolic compounds, tocopherols and sterols are present in all plants and have been studied
extensively in cereals, nuts and oil. n-3 fatty acids are present in fish and all around the
vegetable kingdom.
The aim of the present work was the determination of bioactive and potentially toxic
compounds in cereal based foods and nuts.
The first section of this study was focused on the determination of bioactive compounds in
cereals. Because of that the different forms of phytosterols were investigated in hexaploid
and tetraploid wheats. Hexaploid cultivars were the best source of esterified sterols (40.7%
and 37.3% of total sterols for Triticum aestivum and Triticum spelta, respectively).
Significant amounts of free sterols (65.5% and 60.7% of total sterols for Triticum durum
and Triticum dicoccon, respectively) were found in the tetraploid cultivars.
Then, free and bound phenolic compounds were identified in barley flours. HPLCESI/
MSD analysis in negative and positive ion mode established that barley free flavan-3-
ols and proanthocyanidins were four dimers and four trimers having (epi)catechin and/or
(epi)gallocatechin (C and/or GC) subunits. Hydroxycinnamic acids and their derivatives
were the main bound phenols in barley flours. The results obtained demonstrated that
barley flours were rich in phenolic compounds that showed high antioxidant activity. The
study also examined the relationships between phenolic compounds and lipid oxidation of
bakery. To this purpose, the investigated barley flours were used in the bakery production.
The formulated oven products presented an interesting content of phenolic compounds, but
they were not able to contain the lipid oxidation.
Furthermore, the influence of conventional packaging on lipid oxidation of pasta was
evaluated in n-3 enriched spaghetti and egg spaghetti. The results proved that conventional
packaging was not appropriated to preserve pasta from lipid oxidation; in fact, pasta that
was exposed to light showed a high content of potentially toxic compounds derived from
lipid oxidation (such as peroxide, oxidized fatty acids and COPs).
In the second section, the content of sterols, phenolic compounds, n-3 fatty acids and
tocopherols in walnuts were reported. Rapid analytical techniques were used to analyze the
lipid fraction and to characterize phenolic compounds in walnuts. Total lipid chromatogram
was used for the simultaneous determination of the profile of sterols and tocopherols.
Linoleic and linolenic acids were the most representative n-6 and n-3 essential dietary fatty
acids present in these nuts. Walnuts contained substantial amounts of γ- and δ-tocopherol,
which explained their antioxidant properties. Sitosterol, Δ5-avenasterol and campesterol
were the major free sterols found. Capillary electrophoresis coupled to DAD and microTOF
was utilized to determine phenolic content of walnut. A new compound in walnut ((2E,4E)-
8-hydroxy-2,7-dimethyl-2,4-decadiene-1,10-dioic acid 6-O-β-D-glucopiranosyl ester,
[M−H]− 403.161m/z) with a structure similar to glansreginins was also identified. Phenolic
compounds corresponded to 14–28% of total polar compounds quantified. Aglycone and
glycosylated ellagic acid represented the principal components and account for 64–75% of
total phenols in walnuts. However, the sum of glansreginins A, B and ((2E,4E)-8-hydroxy-
2,7-dimethyl-2,4-decadiene-1,10-dioic acid 6-O-β-D-glucopiranosyl ester was in the range
of 72–86% of total quantified compounds.
43
Manios, Stavros G. "Investigating the impact of retail and household practices on the quality and safety of ready-to-eat and ready-to-cook foods". Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7940.
Testo completoAbstract (sommario):
Bacterial responses to environmental stresses may be easily observed and predicted under controlled laboratory conditions. However, realistic conditions encountered during manufacturing, in retail or in households may cause unpredicted responses of spoilage or pathogenic bacteria. Therefore it is essential to identify and understand the microbial dynamics under such conditions. The overall aim of the present study was to simulate the most common environmental conditions and consumer-style practices during storage or preparation of Ready-to-Eat (RTE) and Ready-to-Cook (RTC) products in the domestic environment, and predict the microbial dynamics which may deteriorate the quality or compromise the safety of these foods. Aiming to develop a unified mathematical model for the prediction of the growth of the specific spoilage microorganisms (SSOs), the spoilage pattern of three RTE acidic spreads of low pH was described in relation to microbial, physicochemical and molecular changes during storage. Results showed that the spoilage profile of the products was primarily affected by the initial pH and the storage temperature, despite the differences in their formulation. These findings enabled the assessment of two unified models (polynomial and Ratkowsky) for the prediction of the growth of lactic acid bacteria (LAB; SSOs) in such acidic spreads, using only the initial pH, the concentration of undissociated acetic acid and the storage temperature. The models were validated under realistic conditions in household refrigerators. Despite the abrupt fluctuations of the temperature during validation procedure, they both were able to adequately predict the growth of LAB in the spreads. However, the initial contamination level was proved to be necessary and crucial for the accurate prediction of microbial dynamics. The time-temperature profiles of the validation procedure revealed that the suggested storage conditions were not followed promptly and, therefore, concerns were raised on the effect of such consumer mishandlings on the safety of foods. Therefore, the responses of Salmonella spp. and Escherichia coli O157:H7 to the stresses encountered during frozen storage, thawing and cooking of ground beef, simulating typical scenarios followed by the consumers, were evaluated. The results revealed that the guidelines issued by the food safety authorities lack of some specific points that may affect the safety of the final product, such as the duration of frozen storage and the method of cooking. In particular, it was found that the heat resistance of E. coli O157:H7 was likely increased after long term frozen storage, while cooking in pan-grill did not ensure the safety of the final product, even when cooked at the suggested temperature. As shown in the first study, the initial contamination level played a significant role on the predictions of the models and further on the shelf-life of the products. Therefore, the dynamics of realistically low initial populations of Listeria monocytogenes and Salmonella Typhimurium versus higher levels of the pathogens (such those used during in vitro trials) in RTE fresh-cut salads were compared. In addition, any potential uncertainty sources for the growth potential of the pathogens in broth-based simulations were investigated. Results showed that the growth variability of low inocula is highly affected by the marginal storage temperatures, the indigenous microflora and the availability of nutrients. Because of this, growth from low populations showed the likelihood to exceed the growth derived from unrealistically high inocula, suggesting that ―fail-dangerous‖ implications may derive from such challenge tests. Data derived from this part were compared with broth-based simulations and the results showed that high uncertainty should be expected when extrapolating such predictions from low initial populations in fresh-cut salads, due to the various factors affecting the microbial growth on a real food, which are (inevitably) ignored by broth-based models. Overall, the present Thesis highlights the significant impact of consumer mishandlings on the food safety and quality of foods and contributes to the identification of unpredicted potential risk origins in the domestic environment.
44
Parry-Hanson, Angela Araba Bondzewaa. "Combined boiling and irradiation treatment on the shelf life and safety of Ready-to-eat bovine tripe". Diss., Pretoria [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-04042007-162719.
Testo completo
45
Kim, Kee Deok. "Korea-U.S. trade negotiation on market access : dispute over the Korean shelf-life regulations for food products". Thesis, University of Kent, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327445.
Testo completo
46
Shearer, Christine Nicole. "Accelerated Shelf Life Determination of Antioxidant Stabilized High Oleic Sunflower and Canola Oils in Plastic Bottles". BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2799.
Testo completoAbstract (sommario):
Vegetable oil is an important commodity; however, the majority of commercially available vegetable oils have a fairly short shelf life, which limits their usefulness for long term food storage, disaster relief, space travel, food aid programs, and military rations. Vegetable oils with high oleic acid and reduced linolenic acid contents, especially with added antioxidant combinations, were previously found to have significantly longer oil stability index (OSI) values than traditional vegetable oils. This study used accelerated shelf life testing to estimate the ambient shelf life of high oleic sunflower oil (HOSUN) and high oleic canola oil (HOCAN), each containing 1,000 ppm ascorbyl palmitate, 200 ppm tertiary butyl hydroquinone, and 200 ppm mixed tocopherols. Oils were stored in the dark in low density polyethylene (LDPE), or polyethylene terephthalate (PET) bottles at 30, 40, 50, and 60°C. Control samples were stored in the dark in glass bottles at -50°C. Testing included peroxide values, qualitative headspace volatile analysis, descriptive sensory analysis, and consumer sensory acceptance. The estimated shelf life was calculated from the change in overall acceptance score over time using the Q10 method. The stabilized HOCAN in PET bottles was estimated to have a shelf life at ambient temperature of 6.8 years, while oil stored in LDPE bottles had an estimated shelf life of only 2.7 years. The estimated shelf life of HOSUN at room temperature in PET is 2.6 years and in LDPE is 0.88 years.
47
Su, Yen-Kan. "Effects of Potassium Lactate, Encapsulated Citric Acid and Storage Temperature on Microbial Growth and Shelf Life of Pork Sticks". DigitalCommons@USU, 1992. https://digitalcommons.usu.edu/etd/5393.
Testo completoAbstract (sommario):
A new product, pork sticks, was developed. Optimum shelf life and safety were major concerns associated with this product. Potassium lactate (3%) or citric acid (0.5%, 0.56%, 0.60% or 0.66%) was added to pork sticks to determine their effects on microbial growth, sensory evaluation, and shelf life when stored frozen (-20°C), refrigerated (2°C), or at room temperature (22°C). Two raw materials, pork blade meat (shoulder meat; 91% lean, 9% fat) and regular 80:20 pork trim (80% lean, 20% fat) were used. The consumer panel preferred lean pork sticks made from blade meat over high-fat pork sticks made from regular 80:20 pork trim, regardless of the addition of potassium lactate (3%) or citric acid (0.5%). Pork sticks vacuum-packaged and held at 2°C or -20°C did not develop bacterial spoilage during six months storage. However, bacterial spoilage and oxidative rancidity occurred in the unpackaged control samples held at 22°C for one month. Incorporation of potassium lactate (3%) or citric acid (0.5%) decreased the color uniformity and red color intensity and increased the brown color intensity of the pork sticks made from blade meat. Vacuum-packaged pork sticks with added citric acid (0.56%, 0.60% and 0.66%) stored at 22°C did not develop bacterial spoilage, but discoloration occurred after one month storage.
48
Bowers, Jordan Whitney James McKee Shelly R. "The effect of acid marinades on Listeria monocytogenes, shelf-life, meat quality, and consumer acceptability of beef frankfurters". Auburn, Ala, 2009. http://hdl.handle.net/10415/1884.
Testo completo
49
Pollock, Allison Maureen. "Characterization of pulsed light treatment on the shelf-life and safety of vacuum packaged cold smoked salmon". Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=101165.
Testo completoAbstract (sommario):
Listeria monocytogenes is a common post-processing contaminant in ready-to-eat vacuum packaged (VP) cold smoked salmon. Since this psychrotrophic pathogen can grow at refrigerated temperatures (~4°C), other safety barriers in addition to temperature are needed to ensure the continued safety of VP cold smoked salmon. One such novel barrier could be the pulsed light (PL) treatment of the product prior to packaging or treating the product through a transparent package.Pulsed light destruction kinetics of L. monocytogenes were evaluated while dispensed into a liquid media, on the surface of a general purpose agar and on the surface of cold smoked salmon. Results showed that PL technology was an effective surface sanitation method (a decimal reduction time or D-value of 0.91, 1.37 and 2.25 s exposure of PL at 800, 700 and 600 V, respectively, and a resulting z value of 500 V) on the agar plate. However, it had only a limited success when applied to liquid samples as well as directly on the surface of cold smoked salmon (D-value ranged from 93 s to 24 min).
Sensory quality of VP cold smoked salmon subjected to selected PL treatments was monitored during storage for 14 days at 4°C. Both color and odor scores remained within acceptable limits over the 14 day storage period. Subsequent challenge studies were carried out with L. monocytogenes applied on VP cold smoked salmon. An overall reduction in counts was observed in samples stored at 4°C over 28 days; however, after PL treatment (day 0), there was no significant reduction in counts. Color and odor scores maintained acceptable values over 14 days. Additional experiments were carried out to determine the effects of (1) 1.5% salt, (2) 6% oil, (3) a representative salmon media and (4) background microflora (lactic acid bacteria) on the PL inactivation of L. monocytogenes. All of these factors significantly affected the destruction of L. monocytogenes by increasing the D-value (adding resistance to pulsed light destruction).
Overall, these studies have shown that PL treatment in combination with low temperature storage (4°C) has the potential to extend the shelf-life of VP cold smoked salmon products without compromising sensory quality. However further investigation into higher treatment voltages is necessary in order to achieve a higher target kill of L. monocytogenes.
50
Gandy, April Lynne. "THE EFFECT OF PASTEURIZATION TEMPERATURE ON CONSUMER ACCEPTABILITY, SENSORY CHARACTERISTICS, VOLATILE COMPOUND COMPOSITION, AND SHELF-LIFE OF FLUID MILK". MSSTATE, 2007. http://sun.library.msstate.edu/ETD-db/theses/available/etd-07022007-162142/.
Testo completoAbstract (sommario):
The relationship among consumer acceptability, descriptive sensory attributes, and shelf-life was determined for 2 % milk pasteurized at 77, 79, 82, or 85?aC. Pasteurization temperature had no effect (p>0.05) on shelf-life. Consumers preferred (p<0.05) 79?aC over other treatments on day 0; however, six days post-pasteurization 79?aC milk was only preferred (p<0.05) over 77?aC. Consumers were grouped into eight clusters based on product liking for both day 0 and 6 evaluations. The largest cluster liked all pasteurization treatments, and 79?aC was highly acceptable to all consumers that liked milk. Similar sensory descriptors indicated the end of shelf-life for all pasteurization treatments even though treatments could be differentiated by descriptors on day 0. This research reveals that altering pasteurization temperature from 79?aC may cause a decrease in consumer acceptability to some consumers. Altering pasteurization temperature does not affect shelf-life or sensory descriptors and volatile compound profiles at the end of shelf-life.