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1
Robinson, Tobin. "The microbiology of food microenvironments". Thesis, Cardiff University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387586.
Testo completo
2
Olaonipekun, Basirat Arinola. "Application of predictive food microbiology to reduce food waste". Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/65935.
Testo completoAbstract (sommario):
Universal food insecurity continue to be a challenge that needs attention from all stakeholders. The problem of food waste however is highly important as it slows down the effort to improve food security, most especially in the world’s poorest countries. Conservative shelf life estimation of RTE foods by food producers is one of the major contributor to food waste. After a survey was carried out on the different RTE food products (n=195) available on the shelf of 3 supermarkets in Hatfield, with their set shelf life and storage instructions. Microbiological quality (Total viable count, LAB, Enterobacteriaceae, yeasts and moulds, and Pseudomonas spp.) and safety (E. coli, Staphylococcus aureus, Listeria spp. and Salmonella spp.) was conducted on selected RTE products (used as a reference point) during storage at ± 5o C. This wass to evaluate the validity of the set shelf life of beef lasagne (3 days), egg noodles (3 days), pre-cut mango (4 days) and pre-cut papaya (4 days) by food producers. Challenge test study was also conducted on representative RTE food products (beef lasagne, egg noodles, and pre-cut mango) with relevant food borne pathogens (L. monocytogenes, Salmonella Typhimurium, and E. coli) during storage for 12 days at ± 5oC. Growth potential (?) of these pathogens in the RTE foods were calculated using the concept of EU-CRL technical guidance on shelf life for L. monocytogenes on RTE foods as ? values can be very useful in potential food safety risk evaluation. Performance of 4 different types of software (ComBase, PMP, MicroHibro & FSSP) was evaluated for use in shelf life estimation of these selected RTE foods. These software were selected based on different criteria (User-friendly, accessibility and availability and types of pathogens for its application). The predicted growth from these software were compared to observed growth (generated from experimental data got from challenge test) of L. monocytogenes in beef lasagne and egg noodles. Indices of performance; Coefficient of determination (R2), root mean square error (RMSE), bias factor (Bf) and accuracy factor (Af) were used to evaluate the performance of these software. All the RTE food products reviewed had no specific refrigeration storage temperature instruction on the product package. Storage test study indicated that some of these RTE foods (beef lasagne, pre-cut mango and papaya) could have longer shelf life (5, 13 and 5 days respectively), while egg noodles could be a potential public health risk due to the presence of food borne pathogens right from day of purchase. However, the challenge test results also confirmed the conservative shelf life estimation by food producers in that the shelf life of all the products evaluated can be extended (Beef lasagne by 6 days, Egg noodles by 6 days and pre-cut mango by 9 days) with no food safety risk associated with the extension. On the other hand. RTE egg noodles and beef lasagne may support the growth of L. monocytogenes (? > 0.5 log10 cfu/g) if present in the food while egg noodles may not support the growth of S. Typhimurium (? ? 0.5 log10 cfu/g). Beef lasagne and pre-cut mango may also not support the growth of E. coli (? ? 0.5 log10 cfu/g). Growth of L. monocytogenes predicted by ComBase, PMP, MicroHibro & FSSP in beef lasagne and egg noodles was in agreement with the observed growth from the challenge test study, with a fail-safe prediction. However, ComBase predictor had the closest prediction to the observed growth. Hence, it had overall best performance for prediction compared to the other software. Notwithstanding, all the software evaluated in this study can be applied in shelf life prediction of RTE food products. Predictive microbiology is a field of food microbiology that can be looked into and implemented by the authorities. Its use by the South African food industry to scientifically estimate the shelf life of RTE food products is thereby encouraged. This will assist in decision making with regards to food quality and safety, thereby reducing the problem of food waste as result of product shelf life and at the same time protect public health.Dissertation (MSc)--University of Pretoria, 2017.
Food Science
MSc
Unrestricted
3
Lombard, Bertrand. "Les essais inter-laboratoires en microbiologie des aliments Inter-laboratory studies in food microbiology". Phd thesis, INAPG (AgroParisTech), 2004. http://pastel.archives-ouvertes.fr/pastel-00001258.
Testo completoAbstract (sommario):
La validité des contrôles microbiologiques, réalisés dans l'objectif d'assurer la sécurité sanitaire des aliments, nécessite notamment l'obtention de résultats d'analyse fiables. La fiabilité des résultats implique l'utilisation de méthodes validées, mises en œuvre par un laboratoire compétent. Les essais inter-laboratoires permettent de s'assurer, du moins en partie, du respect de ces deux conditions. Cependant, en raison de limites expérimentales, ces essais ne sont pas aussi largement pratiqués dans le domaine de la microbiologie des aliments qu'ils ne le sont dans d'autres domaines analytiques. Dans un premier temps, une revue des documents de référence permet d'établir un état des lieux. Cette revue concerne les trois objectifs que l'on peut assigner à des essais interlaboratoires, à savoir l'évaluation de méthodes d'analyse, celle des laboratoires, et la caractérisation de matériaux de référence. Les documents de portée générale, puis ceux spécifiques de l'analyse des aliments, sont pris en compte, et leur degré d'applicabilité à l'analyse microbiologique des aliments est envisagé. Les référentiels et pratiques propres au domaine d'intérêt traité sont finalement présentés, et les déviations par rapport aux documents généraux analysées. Sur cette base, sont présentées les conditions de mise en œuvre de deux types d'essais interlaboratoires, soit la validation de méthodes dans le cadre d'un projet européen du 4ème Programme Cadre de Recherche & Développement d'une part, et l'évaluation de laboratoires par le biais d'essais d'aptitude pour les Laboratoires Nationaux de Référence sur le lait d'autre part. Les difficultés relatives au protocole expérimental, et liées aux spécificités de la microbiologie, sont mises en exergue. Les modes d'exploitation des résultats, en fonction des objectifs et de la nature, qualitative ou quantitative, de la détermination, sont expliqués. En ce qui concerne la caractérisation de la performance des méthodes d'analyse, l'utilisation de statistiques robustes pour estimer la fidélité des méthodes quantitatives est discutée, ainsi que la façon de caractériser la fidélité comme la justesse des méthodes qualitatives. Sur ces aspects, des perspectives d'amélioration sont envisagées. L'intérêt de l'organisation des essais inter-laboratoires en microbiologie des aliments est ensuite abordé. Celui-ci réside dans l'utilisation que l'on peut faire de ces essais comme éléments incontournables de validation d'une méthode d'analyse et d'évaluation d'un laboratoire afin, d'une part, de crédibiliser ou d'améliorer les méthodes d'analyse normalisées au niveau international, et d'autre part d'estimer l'incertitude de mesure attachée aux résultats d'analyse. Quant aux limites de ces essais, essentiellement d'ordre expérimental, elles tiennent surtout à la nature vivante de l'analyte, et concernent des questions de représentativité.
4
Grant, Irene Ruth. "The microbiology of irradiated pork". Thesis, Queen's University Belfast, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335332.
Testo completo
5
Mendoza, L. S. "The microbiology of cooked rice and fish fermentation". Thesis, University of Reading, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356490.
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6
Eames, Malcolm. "United Kingdom Government food research and development policy : food safety, food science and the consumer". Thesis, University of Sussex, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238807.
Testo completo
7
Robles, de la Terre Raul Rene. "Modelling continuous solid/liquid countercurrent food extractions". Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363805.
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8
Macario, Nancy. "The application of predictive food microbiology to improve the quality of milk". Thesis, Queensland University of Technology, 1995. https://eprints.qut.edu.au/37198/1/37198_Macario_1995.pdf.
Testo completoAbstract (sommario):
In traditionally packaged pasteurised milk, shelf-life is usually limited by Pseudomonas fluorescens. In aseptically packaged pasteurised milks in which these post-pasteurisation contaminants are eliminated, Bacillus circulans dominates at spoilage. Storage temperature controls the growth rates of these two spoilage organisms in milk and whether from a health, profit or other point of view, the availability of predictive models to estimate the remaining shelf-life would be of benefit to everyone involved in the food production and distribution chain.
Standard plate counts have traditionally been used for the production of growth rate data but the method has been shown to be time, labour and material intensive. Recently, optical density methods have been the method of choice with little or no attention being paid to the potentially time, labour and material saving conductance methods.
This study was designed to investigate the use of optical density and conductance methods to model the effect of temperature on the growth rate of two spoilage organisms in milk. The models proposed for both organisms were examined for their ability to predict reliably microbial growth in traditionally and aseptically packaged liquid milk products.
Growth curves were obtained for both organisms using optical density and conductance measurements. The Genstat program was used to determine the growth parameters from the optical density data while six different calculation methods were used for modelling of the conductance growth curves. All of the models obtained were validated in real products: P.fluorescens in traditionally packaged pasteurised milks and B.circulans in aseptically packaged pasteurised milks. Optical density was seen to produce fail-safe models within the acceptable range of deviation for P. fluorescens in pasteurised whole white and chocolate flavoured milks. Conductance methods produced more reliable models for B.circulans in aseptically packaged pasteurised milks although bias and precision factors calculated indicated that the models deviated excessively from the real system.
The results of this study support the commercial use of the optical density model for P. fluorescens in pasteurised whole white and chocolate flavoured traditionally packaged milks. While no model was found to be adequate for B.circulans in commercial production of aseptically packaged milk products, the results indicated that when models are derived from good conductance curves, the conductance method potentially may provide models which relate more closely to what is occurring in the real product.
Predictive models are of benefit as they enable the optimisation of food inventory management, assist making decisions regarding the suitability of a particular product for a certain use, help evaluate processes and facilitate the resolution of disputes relating to product quality. While debate continues whether optical density should replace standard plate cou,nts as the traditional method used for the production of the growth rate data, the results of this study encourage further development of the conductance methods.
9
Stuart-Moonlight, Belinda Isobel. "Microbial survival on food contact surfaces in the context of food hygiene regulation". Thesis, King's College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249535.
Testo completo
10
Hong, Wan Soo. "The development of a methodology for assessing food quality in hospital food service systems". Thesis, Sheffield Hallam University, 1993. http://shura.shu.ac.uk/19824/.
Testo completoAbstract (sommario):
There are few empirical studies of food quality within hospital food service systems. Although it is widely accepted that food quality is a multi-faceted phenomenon, much attention has been paid to single component explanations in the past. The aim of this study throughout has been two fold - to develop a model suitable for evaluating the quality of food in conventional hospital food service systems; and to evaluate food quality in selected hospitals in the Trent Regional Health Authority and West Midland Regional Health Authority using the model. A key outcome in this study has been the development of a multifaceted measurement of food quality to help catering managers deploy resources effectively, in conventional hospital food service systems. This approach was achieved using a variety of qualitative and quantitative information to score six food quality components and 15 influencing variables. Food quality was defined as a multi-dimensional measure to include measures of satisfaction of patients and catering staff, productivity, safety, and nutritional adequacy. Measures of influencing variables were chosen or adapted from those available in food service operations insofar as was possible. Where none was available, methods were developed. The variables were grouped into two major categories: human resources and system resources. A survey of 12 hospital conventional food service systems in the UK was undertaken and detailed information was collected from each, including surveys of 933 patients and 327 catering staff. Patient satisfaction with the quality of hospital food and food-related service was evaluated by patient questionnaires. It was measured by assessing 14variables. Patients seem to be generally satisfied with the food served. In the regression analysis none of the influencing variables explained the component of 'patient satisfaction' at the level of P < 0.05, suggesting that it is a different kind of component from the other 4. Importantly the component 'patient satisfaction' appears to be explained predominantly by patients' own demographic and emotional variables rather than by objective catering system factors. Age and appetite were found to significantly correlate with patient satisfaction scores. The component of food waste was found to have a high negative correlation with patients' satisfaction. It may be possible to use food waste as an index of patient satisfaction in future research. Catering staff - satisfaction was evaluated by measuring employee job attitudes towards five aspects of their job using the Job Description Index (JDI). The JDI is directed toward specific areas of satisfaction rather than global or general satisfaction and was easily administered. The food service workers surveyed in this research were less satisfied with their jobs than are other types of workers in other industries. In the regression analysis total number of patients explains around 36% of the variation in staff satisfaction. The productivity level was based upon the total meal equivalents divided by the total labour hours required to produce and serve them. The regression analysis suggests that around 77% of the variance in productivity is explained by labour cost. The safety component was based upon two elements which were microbiological control and temperature control. The results of regression analysis suggest that the number of menu items and the subsidizing meal ratio explain around 74% of the variation in the safety component. Nutritional adequacy was evaluated indirectly by measurement of food waste. In the regression analysis more than 68% of food waste component can be explained by the variable occupancy rate. Correlations between the food quality components show that a non-significant relationship existed between all but one of the components of food quality studied. A significant negative correlation existed between the patients'satisfaction with the hospital meal and service and the food waste; this was expected. The non-significant correlations between the components of food quality showed the independence of components, confirming the need for a multi-dimensional model of food quality. The findings of this research support the notion that food quality is a multi-faceted phenomenon and have led to the development of a practical way of measuring it.
11
de, Senna Antoinette BoYee. "Screening of biocontrol organisms for the management of phytopathogenic fungi and foodborne pathogens on produce". DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1402.
Testo completoAbstract (sommario):
The multibillion dollar agricultural industry is an important part of the United States economy, and the management of factors that affect crop and human health is imperative to maintaining this economic sector. The fungi Botrytis cinerea, Fusarium pallidoroseum, and Fusarium moniliforme are the causative agents of several plant diseases and can cause significant crop loss both before and after harvest in commodities such as strawberries, lettuce, citrus, and grains. Fungicides are employed to control these phytopathogens, but the use of these chemicals has led to an increase in fungicide resistance and may negatively affect the environment and human health. In addition to plant pathogens, foodborne pathogens also have a substantial impact on the agricultural industry. Foodborne disease outbreaks involving Listeria monocytogenes, Salmonella, and Escherichia coli O157:H7 not only cause considerable economic losses, but can also result in devastating health problems for consumers. The increase in fungicide resistance and number of produce-related foodborne disease outbreaks warrants investigation into additional methods of microbial control for use in the agricultural industry. Many bacterial species, including Lactic Acid Bacteria (LAB) and Bacillus species, produce antifungal and antimicrobial compounds, thus the use of biological control agents pre- and postharvest could augment current methods of pathogen management. The purpose of this study was to screen 22 bacterial isolates for inhibitory activity against the fungal phytopathogens Botrytis cinerea, Fusarium pallidoroseum, and Fusarium moniliforme and the foodborne pathogens Listeria monocytogenes, Salmonella, and Escherichia coli O157:H7 in vitro, then evaluate antimicrobial efficacy of select isolates against the foodborne pathogens on fresh produce.
To evaluate antifungal activity, the bacterial isolates were individually spot-inoculated onto Tryptic Soy Agar, Potato Dextrose Agar, or MRS agar, depending on isolate growth requirements and then a plug of fungal-colonized agar was placed onto the center of the isolate-inoculated plate. Plates were incubated at 24°C for 10 days; fungal growth was evaluated daily, beginning on Day 3. Nine of the 22 isolates screened inhibited all three fungi; inhibition by these isolates ranged from 51-62% for B. cinerea, 60-68% for F. pallidoroseum, and 40-61% for F. moniliforme. Isolates were also screened for biosurfactant activity using the drop-collapse test. Biosurfactant production was detected in seven of the nine isolates. Bacillus megaterium, Bacillus coagulans, Bacillus thuringiensis BT2 and three Bacillus amyloliquefaciens isolates demonstrated strong biosurfactant activity and suppression of all three fungi, and therefore are recommended for further study.
Antimicrobial activity of the isolates was assessed using two methods: LAB isolates were screened using a seeded-overlay method and all other isolates were evaluated by spot inoculating the isolate on pathogen-seeded TSA. Three LAB isolates and six Bacillus isolates suppressed L. monocytogenes, Salmonella, and E. coli O157:H7 in vitro. Based on the results of the screening, three LAB isolates—Lactobacillus plantarum, Pediococcus acidilactici, and Pediococcus pentosaceus—were selected for further evaluation and use in challenge studies on fresh produce.
The role of organic acids in pathogen inhibition was evaluated by incubating L. monocytogenes, Salmonella, and E. coli O157:H7 cultures in the cell-free supernatant (CFS; pH 3.81-4.27) or the neutralized cell-free supernatant (pH adjusted to 6.5 -7.0) of each isolate. When neutralized, the antimicrobial activity of the CFS of the three LAB isolates was greatly diminished, illustrating the role of lactic acid in the inhibition of pathogen growth.
To assess antimicrobial efficacy on Iceberg lettuce, a cocktail of the three LAB isolates (7-8 log CFU/g) was sprayed onto lettuce spot-inoculated with L. monocytogenes (2-3 log CFU/g); lettuce was incubated at 10°C for 14 d. L. monocytogenes levels were 1.84 log lower on LAB-treated lettuce than on untreated lettuce at the end of incubation. Because the LAB cocktail suppressed the growth of L. monocytogenes on lettuce, testing on fresh produce continued using DF1, which was a powdered product comprised of the three LAB isolates and media components. Because DF1 caused substantial browning of Iceberg lettuce after 2 d, Gala apples were chosen to evaluate the antimicrobial activity of DF1 against L. monocytogenes, Salmonella, and E. coli O157:H7.
The effect of DF1 on L. monocytogenes, Salmonella, and E. coli O157:H7 on Gala apples was determined by spraying a Gala apple spot-inoculated with pathogen (6-7 log CFU/plug) with approximately 3 mL of a 20% DF1 solution, then incubating at 20°C for 5 d. After 5 d incubation, L. monocytogenes, Salmonella, and E. coli O157:H7 levels on DF1-treated apples were approximately 4, 2, and 2 log higher than the control, respectively. Based on the results of these experiments, DF1 is not the optimal formulation for the biocontrol of foodborne pathogens on fresh produce.
This study identified several bacterial isolates with potential for use in the biocontrol of plant and foodborne pathogens. Further investigation is required to assess possible use in the agricultural industry, including characterization of bioactive compounds, optimization of biocontrol product formulation, and evaluation of the commercial viability of the biocontrol product
12
Damant, Andrew P. "An investigation into the stability of azo food colours to other food additives in soft drinks". Thesis, University of Reading, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304519.
Testo completo
13
Taylor, Tiffany M. J. "Effect of Antimicrobials and Sodium Replacement Agents on the Survival of Pathogenic Bacteria in Low Sodium Low-Moisture Part-Skim (LMPS) Mozzarella Cheese". DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/1102.
Testo completoAbstract (sommario):
Recent increases in chronic cardiovascular diseases, such as hypertension, have put pressure on the food industry to reduce sodium levels. Dairy products, though full of vital nutrients, are perceived as being high in sodium. However, the reduction of salt in dairy products could potentially alter the microbial stability, as well as cause unfavorable changes in flavor. In order to reduce the sodium level, while maintaining acceptable flavor and microbial stability, salt replacers and alternative antimicrobial agents may need to be introduced into the food matrix. To identify potential antimicrobials for use in reduced sodium dairy products, this study evaluated the efficacy of eight commercially available antimicrobials in TSA, milk agar, and cheese agar. Antimicrobials included MicroGard 100, MicroGard 430, Nisaplin, NovaGard CB1, Protect-M, PuraQ Verdad RV75, SEA-i F75 and VMY1P. Antimicrobials were also tested in combination with six commercial sodium reduction agents (potassium chloride, Puracal PP/USP, Purasal Hi Pure P Plus, PuraQ Verdad NV10, SaltWise 0029 and SaltWise 1029) to if there were any interference with antimicrobial activity.
Antimicrobials with and without sodium reduction agents were added to the agar systems, then a five-strain cocktail of Listeria monocytogenes, Salmonella or Escherichia coli O157:H7 was spread plated at three concentrations: 101, 102 and 104 CFU/plate. Samples were then incubated at 35°C and observed for growth after 24 and 48h. SEA-i F75 was the most effective antimicrobial in each of the agars tested. Additionally, no interactions were observed between SEA-i F75 and any of the sodium replacement agents.
SEA-i F75 was selected for use in a final challenge study using six formulations of LMPS mozzarella cheese: regular sodium control cheese (1.7% NaCl, no antimicrobial added); low sodium control cheese (0.7% NaCl, no antimicrobial added); low sodium treated cheese (0.7% NaCl, treatment with SEA-i F75); low sodium cheese with KCl as salt replacer (0.7% NaCl, 1.0% KCl, treatment with SEA-i F75); low sodium cheese with Alta 2345 as salt replacer (0.7% NaCl, 0.25% Alta 2345, treatment with SEA-i F75); and low sodium cheese with Salona as salt replacer (0.7% NaCl, 0.95% Salona, treatment with SEA-i F75).
Fifteen gram cheese pieces from each formulation were dipped in an antimicrobial solution containing 0.25% SEA-i F75 then inoculated with L. monocytogenes, Salmonella, or E. coli O157:H7 at a target inoculum concentration of 102-103 CFU/g and incubated at either 4° or 12°C. In all trials, over all formulations and temperatures tested, initial decreases in counts, followed by organism recovery were observed. Therefore, SEA-i F75 was not effective at reducing the counts of pathogenic bacteria in LMPS mozzarella cheese.
Results from this study highlight the effect of the food matrix, and its components on antimicrobial efficacy. Future research includes examining the effect of one of the other antimicrobials in LMPS mozzarella cheese.
14
Wang, Weiyao. "Food packaging design for older consumers". Thesis, Birmingham City University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264688.
Testo completoAbstract (sommario):
This research centres on product package design related to older people's emotional needs. In particular, knowledge concerning the design of packages for transgenerational use linked to background social data has been elicited. The most distinctive accomplishment has been an exploration of the visual appeal of packaging design in relation to age, gender, education and emotional preference of older consumers. Findings are primarily related to the interaction older people in the UK with selected aspects of package design. Three areas of research have been brought together in this thesis: packaging design and multiple choice, emotional/psychological preference for packaging design characteristics and colour appeal associated ..w ith food character in packaging design. Investigations into the 'third age' and classifications beyond utilised a large sample from the 'Thousand Elders' and a range of packaging designs for selected food items. The significant findings indicate that familiarity and emotional response to packaging designs are key determinants in older consumers' intentions to purchase. Design relating to overall perception or technical cognition are shown to correlate with age related emotional feelings of arousal. Specific findings on such correlations are described in detail. A further 'emotional appeal' was found with colour; for example, green, yellow or bright tones were the most popular colour hue and value associated with varied qualities for food packaging design for specific age groups. Differences between ages, gender and education levels (hypothesised variables linked to design choices) are also analysed and correlated; for example, gender and age rather than educational level combinations appeared to significantly influence choice. Males aged between 55 and 64 relied on their experience of functional aspects for packaging design when considering a purchase. Females in the older age group of 65-74 were more emotional and considered visual appeal in a more personal way. However, few distinguishable psychological effects were noted for the over 75 year olds in their relationship with design. Personal characteristics of older people and their choice are presented in a combination of qualitative interpretation and numeric analysis. Key findings relate to the specific nature of older consumers behaviour in their engagement with packaging design.
15
Galazka, Vanda Barbara. "Protein-polysaccharide interactions in food emulsions". Thesis, University of Leeds, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305638.
Testo completo
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Eves, Anita. "Physiological methods of food texture measurement". Thesis, University of Reading, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252941.
Testo completo
17
Violaris, Yiannis Vasou. "Monitoring and control of risks associated with food production and food handling : the HACCP system and its application to the food businesses with particular regard to Cyprus". Thesis, University of Surrey, 2003. http://epubs.surrey.ac.uk/2190/.
Testo completo
18
Racicot, Bergeron Catherine. "Food animal reservoir for extraintestinal pathogenic «Escherichia coli» causing human infections". Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104886.
Testo completoAbstract (sommario):
Studies of extraintestinal infections caused by genetically related strains of Escherichia coli among unrelated people have demonstrated the epidemic potential of this group of bacteria. These related extraintestinal pathogenic E. coli (ExPEC) may have a common source. Our group recently described how retail meat, particularly chicken, may be a reservoir for ExPEC causing human urinary tract infections (UTIs). By moving upstream on the farm to fork continuum, this study tests whether the reservoir for ExPEC is in food animals themselves. A total of 824 geographically and temporally matched E. coli isolates from cecal contents of slaughtered food animals (n=349) and human UTI (n=475) sources were compared. Using 6 different typing methods, an evolutionary relationship was observed between E. coli isolates from the food animal reservoir and human UTI. Moreover, chicken was the predominant animal species from where the related isolates originated. Using an evolutionary model, chicken was determined to be the most likely source of the human UTI isolates. This study confirmed that an animal reservoir, principally in chicken, may exist for ExPEC causing community-acquired UTI.Les études portant sur les infections extra-intestinales causées par des souches d'Escherichia coli génétiquement apparentées, chez des personnes non reliées entre elles, ont démontré le potentiel épidémique de ce groupe de bactéries. Ces souches d'E. coli pathogènes extra-intestinales (ExPEC) apparentées auraient possiblement une source commune. Notre groupe a récemment décrit comment la viande de détail, plus particulièrement le poulet, pourrait être un réservoir d'ExPEC responsables d'infections urinaires (IUs) chez les humains. En se déplaçant plus en amont dans le continuum de la ferme à la fourchette, cette étude teste si le réservoir d'ExPEC se trouve dans les animaux de production eux-mêmes. Un total de 824 isolats d'E. coli de provenances géographique et temporelle communes, prélevés dans le contenu caecal d'animaux abattus (n=349) et de cas d'IU humaine (n=475) ont été comparés. Par l'utilisation de 6 différentes méthodes de typage, une relation évolutionnaire a été observée entre les isolats d'E. coli provenant du réservoir animal et d'IU humaine. De plus, le poulet était l'espèce animale prédominante parmi les isolats parentés. L'utilisation d'un modèle évolutionnaire a permis de déterminer que le poulet est la source la plus probable des isolats d'IU humaine. Cette étude a confirmé qu'un réservoir animal, principalement chez le poulet, pourrait exister pour les ExPEC qui causent des IUs acquises en communauté.
19
Edwards, J. S. A. "Military feeding : an evaluation of the nutritional status, food habits and food preferences of the British Army". Thesis, University of Surrey, 1986. http://epubs.surrey.ac.uk/804475/.
Testo completo
20
Piette, J. P. Gabriel (Jean-Paul Gabriel). "Heat treatment of staphylococcal enterotoxins B and C2 in extract from fermented sausage". Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66174.
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21
Bahroun, Najat. "Detection of Salmonella in food samples using exogenous volatile organic compound metabolites". Thesis, Northumbria University, 2017. http://nrl.northumbria.ac.uk/32550/.
Testo completoAbstract (sommario):
Rapid, sensitive and selective detection and identification of pathogens is required in the prevention and recognition of problems related to food security. Salmonella is one of the dangerous foodborne pathogens. The identification of specific volatile organic compounds (VOCs) produced by Salmonella may contribute in providing a fast and accurate detection method for Salmonella in food samples. In this study, VOCs liberated by Salmonella strains have been identified and quantified via head space-solid phase microextraction coupled to gas chromatography/mass spectrometry (HS-SPME GC/MS). The dominant chemical class of volatiles liberated from Salmonella strains was alcohol compounds. In addition, ester and ketone compounds were also detected. The most sensitive VOCs detected were ethyl octanoate (LOD = 62.0 ng/mL and LOQ = 207 ng/mL) and ethyl decanoate (LOD = 66 ng/mL and LOQ = 219 ng/mL) with the lowest LOD and LOQ when using Rappaport-Vassiliadis Soya peptone (RVS) broth media and polar SPME fiber with polar GC column. The type of culture medium was found to affect the liberated VOCs. For example, 2-heptanone was not detected when S. london and S. stanley were grown in TSB but they were detected and quantified when using BHI as growth media. Also, 1-octanol was detected and quantified in all strains when Salmonella grown in TSB and BHI, and did not detected in all strains when RVS was used as growth media. The research has been extended to include the addition of specific enzyme substrates to the culture medium (RVS). The enzyme substrates are either commercially available or have been synthesised to allow exogenous VOC detection. The specific enzymes targeted in Salmonella were α-galactosidase, C-8 esterase and pyrrolidonyl peptidase. The enzyme substrates used are phenyl α-D-galactopyranoside, 2-chlorophenyl octanoate and L-pyrrollidonyl fluoroanilide respectively. All, except pyrrolidonyl peptidase, are known to give a positive response to Salmonella. This developed methodology was initially applied to pure cultures of S. stanley to evaluate the feasibility of the approach. The developed approach shows potential for future application in food samples to detect and identify Salmonella species in food samples of a level as low as 100 CFU/mL within a 5 h incubation at 37 ºC by the detection of the liberated VOCs. Subsequently the methodology was applied to a range of food samples (milk, cheese, eggs and chicken). It was found that all food samples were Salmonella free; however, false positive was detected due to the presence of other pathogens in the food samples. Inhibition of some of these pathogens in milk and cheese samples was achieved with the addition of 5 mg/L vancomycin and 10 mg/L of novobiocin. To improve the method specificity, it was necessary to deviate from the standard method and use Salmonella selective RVS broth in pre-enrichment step than using non selective one (BPW). This results in a successful detection of Salmonella contamination on milk samples and cheddar cheese samples. However, failed in detect Salmonella in other cheeses. Inhibition of resistant pathogens (Streptococcus salivarius ssp. Thermophilus, Lactobacillus rhamnosus and Enterococcus faecalis) using another combination of selective agents (vancomycin 10 mg/L, novobiocin 10 mg/L, erythromycin 0.75 mg/L and lithium chloride 15 g/L) failed. This study highlighted the benefits of the use of specific enzyme substrates along with antibiotics into Salmonella VOC analysis to improve the specificity of Salmonella detection method. The results of VOC analysis of specific enzymes inherent within Salmonella could be extended to develop a selective portable sensor approach to be used in food production.
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Schnetler, Demona Charlotte. "The microbiology of ostrich meat with reference to prevalent microbial growth and bruises in carcasses". Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/4046.
Testo completoAbstract (sommario):
Thesis (MSc Food Sc (Food Science))--University of Stellenbosch, 2009.ENGLISH ABSTRACT: Fresh ostrich meat competes in well regulated and competitive international markets; therefore food quality and safety are of the utmost importance. At the same time the production process must be well controlled to be cost effective. Losses in meat yield through bruising and the trimming thereof as well as a high initial microbial load that causes a decrease in shelf-life is thus undesirable. The main objectives of this study were firstly to investigate the expected prevalent microbial growth on ostrich meat as well as possible environmental contaminants to establish which bears the greatest risk. Secondly to establish the best practice of removing bruised areas from carcasses from both a microbiological and meat yield perspective. Lastly to investigate bruises on carcasses to predict the possible causes thereof so as to minimize bruising during transport and handling. From this study it was concluded that the prevalent growth on carcasses was predominantly Grampositive which increased ten fold from post-evisceration to post-chilling, this was also associated with a marked increase in Gram-negative organisms. The most dangerous vector for contamination was found to be standing water containing Gram-negative human pathogens including Shigella, Salmonella and E. coli. Bruises to the necks (52.58% of all bruises) were the most frequent, the high side railings on transport trucks the probable cause thereof. It was indicated that aerobic viable counts decreased after cold trimming, where the opposite occurred on warm trimmed surfaces, while the average loss in meat yield per bird due to bruising was smaller for cold trimming.
AFRIKAANSE OPSOMMING: Vars volstruisvleis kompeteer in goed gereguleerde en kompeterende internasionale markte; dus is voedselkwaliteit en –veiligheid baie belangrik. Terselfdertyd moet die produksieproses goed beheer word en koste effektief wees. Verliese aan vleisopbrengs as gevolg van kneusings en die verwydering daarvan, sowel as ‘n hoë inisiële mikro-organisme lading wat ‘n verkorte rakleeftyd tot gevolg het, is dus ongewens. Die hoofdoelwitte van die studie was eerstens om die verwagte mikro-organisme groei op volstruisvleis en op moontlike omgewings kontaminasie bronne te ondersoek om vas te stel watter bronne die grootste risiko dra vir besmetting. Tweedens om die beste praktyd vir die verwydering van kneusings van die volstruiskarkasse te bepaal uit beide ‘n mikrobiologiese en vleisopbrengs oogpunt. Laastens om die omvang en verspreiding van karkaskneusings te ondersoek om die oorsaak daarvan te probeer aandui en sodoende kneusings tydens vervoer en hantering te verminder. Uit die studie was die volgende duidelik; die mikrobiese groei op karkasses was hoofsaaklik Gram-positief, tellings het tienvoudig toegeneem vanaf ontweiding tot na verkoeling, met ‘n gepaardgaande merkbare toename in Gram-negatiewe organismes. Die gevaarlikste oorsaak van omgewingskontaminasie was staande water wat Gram-negatiewe menslike patogene (insluitend; Shigella, Salmonella en E. coli) bevat het. Nekkneusings (52.58% van all kneusings) was die algemeenste; met die hoogte van die kantreëlings van die volstruistrokke die moontlike oorsaak daarvan. Dit is bewys dat die aerobe mesofiele plaattelings afgeneem het na koue verwydering, maar dat die teenoorgestelde gesien is op warm gesnyde areas; die gemiddelde verlies in vleisopbrengs per volstruis as gevolg van kneusingverwydering is kleiner tydens koue verwydering.
23
Goh, Suk Meng. "An engineering approach to food texture studies". Thesis, Imperial College London, 2002. http://hdl.handle.net/10044/1/11411.
Testo completo
24
Wright, Jeremy J. "Magnetic resonance imaging applications in food science". Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319882.
Testo completo
25
Kometa, Nsanyi. "On-line sample preparation for food analysis". Thesis, University of Hull, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262428.
Testo completo
26
Euston, Stephen Robert. "Statistical modelling of food colloids and polymers". Thesis, University of Leeds, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329780.
Testo completo
27
Cassar, Claire. "Bacterial survival and decontamination in relation to food contact surfaces". Thesis, King's College London (University of London), 1999. https://kclpure.kcl.ac.uk/portal/en/theses/bacterial-survival-and-decontamination-in-relation-to-food-contact-surfaces(376ed8d4-39c1-439e-9eb4-90a9700266f0).html.
Testo completo
28
Mattick, Karen. "The survival of Salmonella spp. at high temperature and low water activity". Thesis, University of Exeter, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341195.
Testo completo
29
Colwill, J. "An analysis of food utilisation in restaurants and public houses with particular reference to food waste and fat content". Thesis, University of Huddersfield, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373775.
Testo completo
30
Martin, John Richard. "The implications of the Food Safety Act 1990 for food safety in retailing and catering in England and Wales". Thesis, University of Surrey, 1995. http://epubs.surrey.ac.uk/2127/.
Testo completo
31
Grandinetti, Megan E. "Decay of Macroalgae and Leaves and Their Relation to Detrital Food Webs". TopSCHOLAR®, 2016. http://digitalcommons.wku.edu/theses/1601.
Testo completoAbstract (sommario):
This project addressed if decaying macroalgae and leaf detritus play a major role in the detrital pool of a 7th-order karst riverine system. Decay rates, macroinvertebrates colonization patterns, and change in δ13C values of Cladophora, Platanus occidentalis, and a mix of Acer negundo and A. saccharinum were tracked during summer and autumn months for portions of multiple years.
Packs of air-dried Cladophora, Acer, and P. occidentalis were placed in mesh bags and put in groups (n=4) in wire baskets. Seven baskets were submerged in riffle (0.5 m) and deeper run (2 m) habitats. Benthic organic matter was collected with each pack to see if there was a correlation with δ13C signatures of decaying macroproducers to help understand what is entering the detrital food web.
Summer 2014 Cladophora and Acer were significantly faster to breakdown than Platanus in both habitats. In autumn‒spring 2014‒2015, Cladophora was significantly faster to breakdown than leaves. Isotopic values of Cladophora were not significantly different than leaves in summer 2014 but were significantly more δ13Cdepleted in the autumn‒spring 2014‒2015. There were no significant differences in macroinvertebrate abundance between the macroproducers for either season. Cladophora had significantly lower macroinvertebrate richness in both seasons, lower shredder abundance, but a significantly higher abundance of clingers. The mean δ13C values of benthic detritus were significantly different than all three macroproducers in the summer and significantly different than Cladophora in the run treatment for autumn‒spring.
Seasonality had a strong influence on breakdown rates, leading to greater mass loss of all three species in the warm summer months compared to the cooler autumn‒spring months. The low macroinvertebrate richness and shredder abundance on the decaying macroalga suggests Cladophora may not be consumed by macroinvertebrates but used strictly as habitat. The implication of rapid Cladophora decay during warm seasons, plus few colonizing macroinvertebrate taxa, is that the decaying macroalgae may not pass through a decomposer food web before being remineralized as CO2.
32
Medeiros, Diane. "Epidemiological typing of Campylobacter clinical and food isolates using pulsed-field gel electrophoresis". Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6279.
Testo completoAbstract (sommario):
Campylobacteriosis is the most frequently reported type of acute bacterial gastroenteritis in Canada. In 2000 alone, 11,846 campylobacteriosis cases were reported in Canada. The majority of these cases are sporadic, and their causes remain unknown. An attempt was made to gain a better understanding of the epidemiology of campylobacteriosis, both by identifying foods and environments that harbor Campylobacter spp., and by characterizing clinical, food and environmental isolates using pulsed-field gel electrophoresis (PFGE). Spot maps were also used to determine the geographical relationship of these campylobacteriosis cases. A variety of raw and ready-to-eat foods were tested for the presence of Campylobacter spp. From the 300 samples analyzed, Campylobacter spp. were detected in four samples, one raw beef liver sample and three raw chicken samples. An isolation rate of 9.7% was observed among the raw chicken samples tested, a significantly-reduced percentage, as compared to a 1981 Canadian survey. The prevalence of Campylobacter spp. in a poultry foodservice operation in Ottawa, was also determined from March to August 2001. No Campylobacter spp. were detected in the 125 samples tested. Campylobacter clinical and food isolates were characterized using PFGE with two restriction enzymes, SmaI and KpnI. KpnI produced more complex banding patterns than SmaI, and proved to be more discriminatory. Among the 154 isolates assigned to clusters by SmaI, only 42% gave concordant results with KpnI. In contrast, among the 53 isolates assigned to 23 clusters by KpnI, 87% gave concordant results with SmaI. Five of the 20 concordant clusters represented isolates obtained from the same person, suggesting that some of these individuals may have become re-infected. Spot map analysis revealed a significant clustering of campylobacteriosis cases in the former city of Ottawa, most of which, did not belong to the same postal code. In contrast, very few cases were observed in outlying regions; however, most of these cases belonged to the same postal code, suggesting the possible presence of local outbreaks.
33
Mahmood, A'isha Usman. "Growth and extracellular enzyme production by Bacillus species on food processing waste substrates". Thesis, University of the West of England, Bristol, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386817.
Testo completo
34
Towler, Gary. "Attitudes and other important factors affecting food choice". Thesis, University of East Anglia, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292259.
Testo completo
35
Lareo, Claudia. "The verticle flow of solid-liquid food mixtures". Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242999.
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36
Liu, Shi. "The horizontal flow of solid-liquid food mixtures". Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307898.
Testo completo
37
Beardall, Lindsay M. "Evaluating the impact of cooling methods on biosafety level I Escherichia coli and Bacillus cereus populations in four food products". Thesis, Kansas State University, 2016. http://hdl.handle.net/2097/34573.
Testo completoAbstract (sommario):
Master of ScienceFood Science Institute - Animal Sciences & Industry
Sara E. Gragg
Food preparation in institutional settings is often carried out in large quantities. Food is cooked and then cooled and stored for later service. Improper or "slow" cooling has been identified by the United States Food and Drug Administration (US FDA) as a contributing factor in foodborne illness outbreaks. This study was designed to test the efficacy of cooling technique combinations on controlling microbial growth within pre-cooked taco meat, chili con carne with beans, low sodium marinara sauce, and brown rice food products. These products were cooked to 73.8°C (165°F) and then portioned to 2 and 3-inch depths in steam table pans. Food product was allowed to cool to 60°C ± 5°C (140°F ± 5°F) before inoculation with surrogate Escherichia coli (E. coli) or Biosafety Level I (BSL I) Bacillus cereus (B. cereus). Pans were uncovered or covered with one or two layers of aluminum foil to allow or restrict air exposure and then placed in a -20°C (-4°F) commercial walk-in freezer or situated in ice water baths in a commercial walk-in refrigerator 4°C (39.2°F). Food products were sampled over a 24-hour period (0, 4, 8, 12, and 24 hour time points) for enumeration of microbial populations. Conclusions from the cooling temperature data in this study revealed uncovered pans and pans stored in the freezer at 2-inch food product depths cooled most rapidly. However, few cooling methods achieved the two-step US FDA Food Code requirement for pre-cooked taco meat, chili con carne with beans, and brown rice products and none of the cooling methods tested achieved the US FDA food code requirement for low sodium marinara sauce. Surrogate E. coli and BSL I B. cereus microbial population data revealed pre-cooked taco meat, chili con carne with beans, and brown rice products all exhibited a certain degree of overall population decline during the 24-hour cooling period. However, a small recovery of surrogate E. coli population was observed in the low sodium marinara sauce product as well as 2-inch product depths of the chili con carne with beans product. This observed growth was less than 0.50 log₁₀ CFU/g, indicating low risk for microbial proliferation from the cooling methods tested. It is possible that the surrogate E. coli and BSL I B. cereus population changes observed were not the result of cooling failure or risk, but rather due to natural variations within the food products. These results indicate all 12 cooling methods tested were low risk and therefore effective at controlling E. coli and B. cereus microbial populations within the four food products.
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Morrison, Nathan J. "Inactivation and injury of Salmonella enterica serovar Enteritidis in buffer and whole liquid egg during treatment with mild heat, ozone and their combinations". The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1434646616.
Testo completo
39
Cook, Crystal N. "Development of a Rapid Method for Detection and Differentiation of Escherichia coli Serotypes and Strains Using Attenuated Total Reflectance Fourier Transform Infrared Microspectroscopy". The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1461253150.
Testo completo
40
Wang, Zihua. "Persistence of ESBL E. coli in Poultry Production Free of Antibiotic Application". The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524047763189613.
Testo completo
41
Hussein, Walaa. "Discovery of Novel Lactic Acid Bacteria Strains with Antimicrobial and Probiotic Traits for Beneficial Industrial Applications". The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1595587732038431.
Testo completo
42
Liserre, Alcina Maria. "Microencapsulação de Bifidobacterium lactis para aplicação em leites fermentados". Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/9/9131/tde-26042016-181206/.
Testo completoAbstract (sommario):
Bifidobacterium spp. são microrganismos probióticos que podem ser incorporados em produtos alimentícios. Entretanto, para que seus efeitos benéficos à saúde humana ocorram, é necessário que o número de células viáveis na hora do consumo seja, no mínimo, 106UFC/g. As bifidobactérias são sensíveis à elevada acidez e, por isso, torna-se necessária a busca por métodos que possam proteger a integridade da célula, sendo um deles a microencapsulação. Em uma primeira etapa do trabalho, Bifidobacterium lactis foi encapsulado em micropartículas de alginato e alginato modificado (alginatoquitosana, alginato-quitosana-sureteric e alginato-quitosana-acryl-eze) e sua sobrevivência e liberação das micropartículas em fluidos simulados do trato gastrintestinal foram mensuradas utilizando-se soluções tampão com pH 1,5, 5,6 e 7,5, na presença e na ausência de pepsina (3g/L), pancreatina (1g/L) e bile (10g/L). A liberação de células das micropartículas teve uma relação direta com o pH do tampão. A microencapsulação aumentou a taxa de sobrevivência de B. lactis, em comparação com células não encapsuladas, em soluções tampão com pH 1,5 sem a presença de enzimas. Em suco gástrico simulado com enzimas digestivas, por outro lado, foi observado que a pepsina proporcionou um efeito protetor sobre as células de B. lactis, e nesse caso, as taxas de sobrevivência do microrganismo estavam diretamente relacionadas com o grau de injúria das células. Em uma segunda etapa do trabalho, leites fermentados com Streptococcus salivarius ssp. thermophilus e Lactobacillus delbrueckii ssp. bulgaricus foram enriquecidos com culturas de Bifidobacterium lactis submetidas a quatro tratamentos diferentes: desidratação em temperatura ambiente, liofilização/congelamento, encapsulação em alginatoquitosana e encapsulação em alginato-quitosana-acryl-eze. A população sobrevivente de B. lactis foi determinada semanalmente no leite fermentado e também após tratamento simulando condições do trato gastrintestinal. Os resultados indicaram que na ausência de pepsina, as populações de B. lactis foram reduzidas drasticamente após o contato com tampão pH 1,5, não sendo possível a detecção de células viáveis livres ou encapsuladas após 120 minutos de teste. A presença de pepsina influenciou positivamente a recuperação de células viáveis de B. lactis em todas as condições testadas, mas as culturas na forma desidratada apresentaram melhores resultados que as culturas microencapsuladas ou liofilizadas. No caso do leite fermentado contendo as células desidratadas, a população de B. lactis, após o tratamento em suco gástrico com enzimas, foi superior à detectada no produto antes desse tratamento. Conclui-se que a microencapsulação não foi eficiente para proteger B. lactis em leite fermentado contra injúrias causadas pelo trato gastrintestinal simulado.Bifidobacterium spp. are microorganisms that can be added to foods. However, the benefits for the human health occur when the numbers of viable cells in the moment of the consumption is at least 106CFU/g. Bifidobacteria are acid sensitive, and methods to protect cell integrity, such as microencapsulation, are needed. In the first part of the present study, Bifidobacterium lactis was encapsulated in microparticles of alginate and modified alginate (alginate-chitosan, alginate-chitosan-sureteric and alginate-chitosan-acryl-eze) and the survival and release from microparticles in simulated gastrointestinal conditions were measured, using buffers (pH 1.5, 5.6 and 7.5), in the absence and presence of pepsin (3g/L), pancreatin (1g/L) and bile. The release from microparticles presented a direct relationship with pH. When the pH was 1.5 and no enzyme was present, encapsulation improved the survival of B. lactis, when compared to free cells. However, pepsin had a protective effect on B. lactis, and the survival rate was directly related to the cells injury degree. In the second part of the study, fermented milk samples containing Streptococcus salivarius ssp. thermophilus and Lactobacillus delbrueckii ssp. Bulgaricus were supplemented with B. lactis submitted to four different treatments: dehydration at room temperature, freeze drying, encapsulation in alginate-chitosan and encapsulation in alginate-chitosaacryl-eze. The number of viable B. lactis cells in the fermented milk was determined weekly and also after treatment with simulated gastrointestinal conditions. Results indicated that in the absence of pepsin, the number of viable cells decreased significantly after contact with buffers (pH 1.5), and no viable cell was detected after 120 minutes. Pepsin improved the recovery of viable cells in the assayed gastric conditions, being the dehydrated cultures more resistant than other cultures. In fermented milk containing the dehydrated cells, the number of viable cells increased after treatment with simulated gastrointestinal fluids. Microencapsulation was not an effective procedure to protect B. lactis in fermented milk against injury caused by the simulated gastrointestinal tract.
43
Woskett, Christine Maria. "Competitive adsorption and protein-surfactant interactions in food emulsions". Thesis, University of Leeds, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235613.
Testo completo
44
Baines, Zoe Venetia. "Influence of food texture on flavour and taste perception". Thesis, Cranfield University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293960.
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45
Sakate, Ricardo Ichiro. "Prevalência, epidemiologia, caracterização sorológica e molecular de Listeria monocytogenes isoladas na criação intensiva de Novilhos Superprecoces e em abatedouros frigoríficos no Estado de São Paulo". Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/9/9131/tde-08082017-155252/.
Testo completoAbstract (sommario):
O Brasil é um dos principais exportadores de carne bovina. A maioria do gado é criada a pasto, porém uma parte já é confinada, como na criação de Novilhos Superprecoces. Este confinamento pode favorecer a contaminação por L. monocytogenes (Lm) do rebanho, bactéria responsável pela listeriose, doença que provoca aborto, neuropatias e gastrenterites. Com isto, pesquisou-se a presença e características sorotípicas e moleculares de Lm durante o confinamento de cinco raças de novilhos e em suas carcaças no frigorífico A, assim como amostras de carcaças, utensílios, equipamentos e ambiente em outro frigorífico (B). Foram utilizadas para tipar as cepas técnicas de sorotipagem por multiplex PCR, soroaglutinação e PFGE. Nenhuma Lm foi isolada nas 645 amostras do confinamento, sendo 13/48 carcaças dos novilhos, assim como amostras de piso e parede da câmara fria positivas para Lm no frigorífico A. Das 516 amostras do frigorífico B, 27 continham Lm, sendo a maioria proveniente da área limpa. Verificou-se que os sorotipos 1/2c e 4b foram os mais freqüentes no frigorífico A e o 1/2b e 1/2c no frigorífico B. A análise por PFGE forneceu 15 perfis Ascl, 13 Apal e 21 perfis compostos, caracterizando sete grupos clonais. Nesta cadeia produtiva de carne o principal ponto crítico para Lm está na área limpa do frigorífico e que cepas de mesmos grupos clonais puderam ser encontrados em ambos frigoríficos, assim como em áreas distintas do frigorífico B, demonstrando o alto poder de disseminação destas cepas. Portanto, estes resultados podem auxiliar no desenvolvimento de programas de boas práticas e HACCP para prevenir ou eliminar a contaminação por este patógeno.Brazil is one of the most important beef producer/exporter country worldwide. The majority of the cattle is raised extensively, but some of them are feedloted. Confinement conditions can stress the animals and favor the contamination and proliferation for Listeria monocytogenes (Lm), agent of listeriosis which causes abortion, stillbirths, nervous dysfunctions and gastroenteritis. The aim of this study was to verify the presence of this microorganism and its molecular and serotype characteristics. Two groups of samples were analyzed: first, during the confinement of five different breeds of steers and on their carcasses (abattoir A). Second, at the slaughter and processing of other groups of beef cattle (abattoir B). The Lm strains were serotyped with commercial antisera and by multiplex PCR, and subtyped by PFGE. No Lm was found among the 645 samples of feces, environment, feed and water during the confinement, but 13/48 of the refrigerated carcasses were contaminated, as well as the floor and the wall of the cold room at the abattoir A. Amongst the 516 samples of slaughter and processing environments, carcasses, utensils and equipment collected from abattoir B, 27 harbored Lm, being the majority from the c1ean area. Serotype 1/2b and 4b were the most frequent Lm serotypes in the carcasses of the steers in abattoir 1, and 1/2b and 1/2c in the abattoir B. The molecular typing by PFGE resulted in 15 Ascl and 13 Apal profiles, and 21 composite profiles, resulting in seven clonal groups. In these beef production chains the most important critical point for Lm contamination is the c1ean area of meat processing. Same clonal groups could be isolated in both abattoirs and in different areas on abattoir B, demonstrating high dissemination capability of these strains. Therefore, these results could aid the development of good manufacturing practices and HACCP, to prevent or eliminate the contamination for this pathogen.
46
Silva, Bruna Lourenço da [UNESP]. "Avaliação higiênico-sanitária de produtos minimamente processados comercializados em Botucatu/SP: perfil genotípico e fenotípico das cepas de Staphylococcus sp., em relação à produção de biofilme e de enteroxinas". Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/94793.
Testo completoAbstract (sommario):
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silva_bl_me_botib.pdf: 198846 bytes, checksum: ff23adb2c290d1b6ce0ce5d4e1ddfa11 (MD5)Os alimentos minimamente processados surgiram como uma interessante alternativa para o consumidor que procura por produtos de boa qualidade, saudáveis e de fácil preparo e consumo. No entanto, micro-organismos patogênicos podem estar presentes desde a produção ou serem introduzidos através de equipamentos e utensílios mal higienizados ou pela manipulação inadequada. Sendo assim, o objetivo desse trabalho foi a avaliação microbiológica de hortaliças, legumes e frutas minimamente processados, em relação aos parâmetros microbiológicos descritos na legislação brasileira, que permite até 102/g de coliformes termotolerantes para hortaliças e até 5 x 102/g, para frutas, na ausência de Salmonella em 25 gramas do produto. Entretanto, a legislação não contempla a pesquisa de Staphylococcus aureus, bactéria potencialmente produtora de enterotoxinas, cujo habitat é a mucosa nasal e que pode ser transmitida aos alimentos pela intensa manipulação. Dentro do mesmo gênero, existem as espécies de estafilococos coagulase negativa (ECN), que apresentam grande potencial patogênico, por possuírem os mesmos genes para a produção de enterotoxinas, encontrados em S. aureus. Assim, o trabalho também objetivou o isolamento dessas bactérias, a pesquisa dos genes que codificam a produção de enterotoxinas clássicas e biofilme e, a partir da presença dos genes, foi pesquisada a produção in vitro desses fatores. A produção de biofilme foi verificada em plástico, aço inoxidável e vidro. Foram analisadas 200 amostras, e nenhuma apresentou contaminação por Salmonella, mas 157 (78,5%) estavam fora dos limites aceitáveis em relação à quantidade de coliformes termotolerantes. Em relação aos estafilococos, 50 amostras (25%) apresentaram contaminação por ECN e 7 (3,5%), por estafilococos coagulase...
Minimally processed foods emerged as an interesting alternative for the consumer that seeks for products with good quality, which are healthy, easy to prepare and to consume. Nevertheless, pathogenic microorganisms may be present in these products since production, or may be introduced by badly sanitized equipment and utensils, or by improper manipulation. Therefore, the objective of this work was the microbiological evaluation of minimally processed vegetables and fruits, regarding the microbiological parameters described in the Brazilian law, which allows for up to 10² thermotolerant coliforms in vegetables and up to 5 x 10² in fruits, in the absence of Salmonella in 25 grams of the product. However, the law does not consider the research of Staphylococcus aureus, bacteria that is a potential producer of enterotoxins, whose habitat is the nasal mucosa and that may be transmitted to food by the intense manipulation they are subjected. In the same genus, there are the coagulase-negative staphylococci species (CoNS), which presents huge pathogenic potential, for having the same genes for enterotoxin production found on S. aureus. Thus, this work also aims the isolation of these bacteria, the research of genes that codify for the production of classical enterotoxins and biofilm and, as from the presence of these genes, the research of the production in vitro of enterotoxins and biofilm. The biofilm production was tested on plastic, stainless steel and glass, which are the most used materials in equipments and utensils. 200 samples were analyzed, and none presented contamination by Salmonella, although 157 (78.5%) were outside the acceptable limits regarding the quantity of thermotolerant coliforms. From these 200 samples of minimally processed products, 50 (25%) presented coagulase-negative staphylococci (CoNS) and... (Complete abstract click electronic access below)
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Silva, Bruna Lourenço da. "Avaliação higiênico-sanitária de produtos minimamente processados comercializados em Botucatu/SP : perfil genotípico e fenotípico das cepas de Staphylococcus sp., em relação à produção de biofilme e de enteroxinas /". Botucatu, 2012. http://hdl.handle.net/11449/94793.
Testo completoAbstract (sommario):
Orientador: Vera Lúcia Mores RallBanca: Ary Fernandes Junior
Banca: Maria Cecília de Arruda
Resumo: Os alimentos minimamente processados surgiram como uma interessante alternativa para o consumidor que procura por produtos de boa qualidade, saudáveis e de fácil preparo e consumo. No entanto, micro-organismos patogênicos podem estar presentes desde a produção ou serem introduzidos através de equipamentos e utensílios mal higienizados ou pela manipulação inadequada. Sendo assim, o objetivo desse trabalho foi a avaliação microbiológica de hortaliças, legumes e frutas minimamente processados, em relação aos parâmetros microbiológicos descritos na legislação brasileira, que permite até 102/g de coliformes termotolerantes para hortaliças e até 5 x 102/g, para frutas, na ausência de Salmonella em 25 gramas do produto. Entretanto, a legislação não contempla a pesquisa de Staphylococcus aureus, bactéria potencialmente produtora de enterotoxinas, cujo habitat é a mucosa nasal e que pode ser transmitida aos alimentos pela intensa manipulação. Dentro do mesmo gênero, existem as espécies de estafilococos coagulase negativa (ECN), que apresentam grande potencial patogênico, por possuírem os mesmos genes para a produção de enterotoxinas, encontrados em S. aureus. Assim, o trabalho também objetivou o isolamento dessas bactérias, a pesquisa dos genes que codificam a produção de enterotoxinas clássicas e biofilme e, a partir da presença dos genes, foi pesquisada a produção in vitro desses fatores. A produção de biofilme foi verificada em plástico, aço inoxidável e vidro. Foram analisadas 200 amostras, e nenhuma apresentou contaminação por Salmonella, mas 157 (78,5%) estavam fora dos limites aceitáveis em relação à quantidade de coliformes termotolerantes. Em relação aos estafilococos, 50 amostras (25%) apresentaram contaminação por ECN e 7 (3,5%), por estafilococos coagulase... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Minimally processed foods emerged as an interesting alternative for the consumer that seeks for products with good quality, which are healthy, easy to prepare and to consume. Nevertheless, pathogenic microorganisms may be present in these products since production, or may be introduced by badly sanitized equipment and utensils, or by improper manipulation. Therefore, the objective of this work was the microbiological evaluation of minimally processed vegetables and fruits, regarding the microbiological parameters described in the Brazilian law, which allows for up to 10² thermotolerant coliforms in vegetables and up to 5 x 10² in fruits, in the absence of Salmonella in 25 grams of the product. However, the law does not consider the research of Staphylococcus aureus, bacteria that is a potential producer of enterotoxins, whose habitat is the nasal mucosa and that may be transmitted to food by the intense manipulation they are subjected. In the same genus, there are the coagulase-negative staphylococci species (CoNS), which presents huge pathogenic potential, for having the same genes for enterotoxin production found on S. aureus. Thus, this work also aims the isolation of these bacteria, the research of genes that codify for the production of classical enterotoxins and biofilm and, as from the presence of these genes, the research of the production in vitro of enterotoxins and biofilm. The biofilm production was tested on plastic, stainless steel and glass, which are the most used materials in equipments and utensils. 200 samples were analyzed, and none presented contamination by Salmonella, although 157 (78.5%) were outside the acceptable limits regarding the quantity of thermotolerant coliforms. From these 200 samples of minimally processed products, 50 (25%) presented coagulase-negative staphylococci (CoNS) and... (Complete abstract click electronic access below)
Mestre
48
Goodall, Ian Christopher. "The investigation and analysis of carbohydrates to determine food authenticity". Thesis, University of East Anglia, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309963.
Testo completo
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Brooks, Joy Lynne. "Sensor systems for the rapid detection of microorganisms in food". Thesis, University of Reading, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306341.
Testo completo
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Al-Othaimeen, Abdulaziz Ibrahim. "Food habits, nutritional status and disease patterns in Saudi Arabia". Thesis, University of Surrey, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304502.
Testo completo