Thesis (Ph.D.) - University of St Andrews, June 2009.

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Sodium phosphite was evaluated for inhibition of growth of spoilage yeasts in laboratory media and in two commercial carbonated beverages. In addition, the effects of pH and atmosphere in combination with sodium phosphite were also examined in laboratory media. Inhibition studies in laboratory media were performed with optimal or near optimal growth conditions for each yeast. Growth was monitored by measuring optical density at 600 nm. A time to significant growth was determined for experiments in laboratory media and was used to evaluate the effect that sodium phosphite and other test variables had on growth. A time to detectable growth was determined for experiments in commercial carbonated beverages and post incubation counts on observations with undetectable growth were used to evaluate the effects of sodium phosphite on yeast growth. Sodium phosphite was most effective in inhibiting growth of Zygosaccharomyces bailii, and less effective against Saccharomyces cerevisiae, and Saccharomyces uvarum respectively. Results from this investigation show the potential use of sodium phosphite as an antimicrobial food preservative has potential. / Master of Science

Call number: LD2668 .T4 1986 M375 / Master of Science / Chemistry

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Orientador: Rogério Lopes Vieites / Banca: Aline de Oliveira Garcia / Banca: Eliane Maria Ravasi Stéfano Simionato / Banca: Roseli Aparecida Claus Bastos Pereira / Banca: Regina Daiuto Bastos / Resumo: Os figos são comercializados in natura ou processados na forma de doces. A preocupação com a saúde, especialmente à obesidade ou diabetes, tem feito o consumidor buscar opções menos calóricas para manter o prazer de ingerir alimentos doces. A elaboração de produtos com sabor idêntico ao convencional é de grande importância para aceitação destes produtos. O objetivo deste projeto foi desenvolver protocolos de fabricação de compota de figo diet visando o aproveitamento tecnológico e agregação de valor ao fruto respondendo aos interesses da Associação Agrícola de Valinhos e Região. Foram elaboradas compotas de figo verde avaliando diferentes edulcorantes. As formulações da calda foram: calda de açúcar (TA); Sorbitol (TS); Eritritol (TE); Sorbitol e Erititol (TSE); Steviosídeo (TST); Ciclamato de Sódio, Sucralose e Sacarina Sódica (TCSuSa); Ciclamato sódico e Sacarina sódica (TSC); Acessulfame-K e Sucralose (TAcSu); Steviosídeo, Sacarina Sódica e Ciclamato de Sódio (TSSC). Os figos in natura e as compotas foram avaliados quanto teores de sólidos solúveis oBrix, pH, acidez titulável, açúcar redutor-AR e açúcar redutor total-ART, umidade, proteínas, lipídeos e cinzas. Também foram avaliados quanto a cor instrumental, textura, análises microbiológicas e avaliação sensorial através dos testes de ordenação e teste afetivo. Para a qualidade das compotas foram determinados o peso bruto, peso líquido e peso drenado, vácuo e contagem de número de figos no pote. Os valores de todos os atributos físico-químicos avaliados estão de acordo com a literatura e legislação para este tipo de produto. A coloração do figo in natura e da compota mostraram que houve alteração na cor quando os mesmos sofreram tratamento térmico, causando modificação da cor natural dos frutos. Não ocorreu contaminação microbiológica nas compotas e se apresentaram em ... / Abstract: Figs are marketed fresh or processed into sweets. Concern for health, especially with obesity or diabetes, have made consumers look for low-calorie options to keep the pleasure of eating sweet foods. The preparation of products identical to conventional taste is of great importance for acceptance of these products. The objective of this project was to develop diet fig compote manufacturing protocols to technological use and add value to fruit responding to the interests of the Agricultural Association of Valinhos and Region. green fig jam evaluating different sweeteners were prepared. The slurry formulations were: syrup (TA); Sorbitol (TS); Erythritol (TE); Sorbitol and Erititol (TSE); Steviosídeo (TST); Sodium cyclamate, sucralose and saccharin Sodium (TCSuSa); sodium cyclamate and Saccharin (TSC); Acesulfame-K and sucralose (TAcSu); Steviosídeo, Saccharin Sodium and Sodium cyclamate (TSSC). Figs fresh and the jams were evaluated for soluble solids ° Brix, pH, titratable acidity, reducing sugar and sugar-AR full-ART reducer, moisture, protein, lipids and ash. They were also evaluated for instrumental color, texture, microbiological analysis and sensory evaluation through the ordering and affective test tests. For the quality of jams were determined the gross weight, net weight and drained weight, vacuum and number of figs count the pot. The values of all evaluated physico-chemical attributes are consistent with literature and rules for this type of product. Staining fig fresh and compote showed that there was a change in color when they have undergone heat treatment, causing modification of the natural color of the fruit. There was no microbiological contamination in jams and presented in satisfactory sanitary conditions. In sensory analysis, the jams of TA treatments TCSuSa and TSSC were selected in order to test for sweetness and affective test only TA and TCSuSa jams obtained higher scores for... / Doutor

Made available in DSpace on 2014-06-11T19:23:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-03-04Bitstream added on 2014-06-13T19:09:13Z : No. of bitstreams: 1 gusmao_vv_me_sjrp.pdf: 467989 bytes, checksum: f6fb70f81cc15aa3029140a597f0de22 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / No Brasil, o leite possui uma posição de destaque, tanto do ponto de vista social como do econômico. Devido a sua composição peculiar rica em proteínas, gorduras, carboidratos, sais minerais e vitaminas, é considerado como um excelente meio de cultura, pois constitui um ambiente adequado para o desenvolvimento de vários microrganismos. A contaminação microbiana altera a qualidade do alimento e pode agir como veículo de microrganismos patogênicos, que podem provocar o desenvolvimento de doenças infecciosas ou intoxicações alimentares, que colocam em risco a saúde do consumidor e levam à condenação do leite, além da perda da qualidade nutricional do produto. O leite é freqüentemente relacionado com surtos de toxinfecções alimentares, o que justifica a necessidade de avaliações constantes de sua qualidade garantindo a sua condição de consumo. Neste trabalho foram coletadas 23 amostras de leite pasteurizado tipos A, B e C, obtidas no comércio varejista da região de São José do Rio Preto - SP, que foram submetidas as seguintes análises microbiológicas: contagem de bactérias aeróbias mesófilas, enumeração de bolores e leveduras, determinação do Número Mais Provável (NMP) de coliformes totais e fecais, pesquisa de Escherichia coli e de Salmonella spp. Das amostras de leite analisadas foram isoladas 31 culturas de leveduras, submetidas às provas taxonômicas, morfológicas, fisiológicas e de assimilação de diversas fontes de carbono. De acordo com os resultados obtidos, observou-se que apenas 2 (8,70%) amostras apresentaram coliformes fecais acima do limite da legislação, resultado este, inferior aos diversos trabalhos encontrados em leite pasteurizado desenvolvidos em diferentes regiões do Brasil. A presença de Escherichia coli foi constatada em apenas 3 amostras, sendo todas do tipo C. A de Salmonella spp não foi verificada em nenhuma... / In Brazil, milk has a prominent position, as much of social point of view as of economic, due to its particular composition rich in proteins, fats, carbohydrates, mineral salts and vitamins, and consequently it is considered like an excellent medium, because it s an adequate atmosphere for the development of several microorganism. The microbial contamination changes the food quality, so that it may act like vehicle of pathogenic microorganism, promoting disease or food poisoning, risking consumer s health and milk may be condemned; besides the loss of product s nutritional quality. Milk is frequently related to outbreaks of food toxinfection, what justify the need for constant evaluations of its quality as well as the guarantee of its condition of consumption. In this study 23 samples of kinds A, B and C pasteurized milk were obtained from the retail trade of São José do Rio Preto (SP) region and were done the following microbiological analyses: counting of mesophilic aerobic bacteria, listing of molds and yeasts, determination of most probable number (MPN) of total coliforms and fecal coliforms, research of E. coli and Salmonella spp.. Thirty one yeast cultures were isolated from the samples. They were submitted to taxonomic, morphological, and physiological tests and to carbon source assimilation test. According to the results obtained, only 2 (8.70%) had fecal coliforms above the regulation limit. The percentage out of the microbiological standard (8.70%) was lower than several studies found in pasteurized milk, developed in different regions of Brazil. E. coli was detected in 3 samples of kind C. Salmonella spp. was not detected in any sample analyzed, what is in accordance with the current regulation. In conclusion, most of the samples (91.30%) had coliforms a 45°C 4 MPN/mL, xii consequently were labeled as products in satisfactory sanitary conditions, therefore products...(Complete abstract click electronic access below)

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / The food industry uses chemical additives to extend the shelf life of its products and maintain their sensory and microbiological characteristics acceptable. However, the presence of preservatives in foods may interfere in the quantification of total antioxidant activity. Therefore, this study aimed to evaluate the influence of food preservatives on total antioxidant activity and on the sensory and microbiological quality of acerola tropical juice. The fruits were washed, sanitized (200 ppm sodium hypochlorite), pulped and then were formulated with water and its specific preservatives. The juices were heat treated (90ÂC/60 seconds) and hot filled in glass bottles, which were closed, cooled until 35ÂC and stored at 25ÂC for 180 days. The formulations tested were: control juice without additive (C); juice with addition of 0.004 g/100 mL of sodium metabisulphite (SMS); juice with addition of 0.08 g/100 mL of potassium sorbate (SSP); juice added of 0.05 g/100 mL of sodium benzoate (SBS); juice added of 0.002 g/100 mL of sodium metabisulfite and 0.04 g/100 mL of potassium sorbate S(MS+ SP); juice with addition of 0.002 g/100 mL of sodium metabisulfite and 0.025 g/100 mL of sodium benzoate S(MS + BS). It was carried out chemical determinations for ascorbic acid, total carotenoids, total anthocyanins, total extractable polyphenolics and total antioxidant activity by ABTS and DPPH methods. Commercial sterility testing was performed on samples to determine the hygienic and sanitary processing and to check for any microbiological changes. In sensory acceptance tests were used acerola nectars, prepared by dilution from the acerola tropical juice and added sucrose to obtain 11 ÂBrix, using a 9-point hedonic scale for flavor, color, aroma, sweetness, appearance, body and overall impression. The experiments were performed at three time points (0, 90 and 180 days) and the determinations were made in triplicate. The results were analyzed by the interaction between the juice type and storage time. Regarding anthocyanins content, all samples showed an average of 1.0 mg/100mL (P> 0.05). The acid ascorbic contents remained stable during the storage and ranged from 256.22 mg/100mL (C juice) to 301mg/100mL (SMS and SSP juices). The total carotenoid in treatments with or without preservatives did not vary significantly among themselves, with mean values of 0.04 mg/100mL. The yellow flavonoids showed no significant difference between the juice type (P> 0.05), averaging 5.30 mg/100 mL. For soluble dark pigments, SMS obtained the lowest range in absorbance at 90 days time (0.170 to 0.240), and greater variation for the control juice (from 0.230 to 0.320). All samples showed high losses of phenolics during storage, observing greater losses at times of 0 and 90 days, which ranged from 36.59% for S(BS + MS) and 42.97% for SMS. There was a significant variation of total antioxidant activity with time by the DPPH test (P≤0.05). The values ranged from 877.41 to 978.44 g/g DPPH for C and SMS juices, respectively. A similar behavior was observed for contents analyzed by the ABTS testing: 58.46 mM Trolox/g for SMS and 49.80 mM Trolox/g for control juice. A significant and positive correlation was verified between polyphenols and ABTS (r = 0.78) and DPPH (r = 0.44); anthocyanins and ABTS (r = 0.39) and DPPH (r = 0.44). Yellow flavonoids and ABTS and DPPH assays were negatively and significantly correlated (r = -0.83 and r = -0.52), respectively. There was no significant correlation between ascorbic acid and ABTS and DPPH assays. There was no significant interaction between any treatment and storage time (P> .05). Sodium metabisulphite and its combinations did not influence sensorial acceptance of acerola nectars, with assessments within the acceptable range for all analyzed attributes along storage time. The potassium sorbate and sodium benzoate singly were the additives that contributed most to a higher rejection sensory of products. The employed chemical preservatives, associated with the heat treatment, were effective for maintaining the commercial sterility of acerola tropical juices. / A indÃstria de alimentos utiliza-se de conservantes quÃmicos para prolongar a vida Ãtil de seus produtos e manter suas caracterÃsticas sensoriais e microbiolÃgicas aceitÃveis. Contudo a presenÃa desses conservantes nos alimentos pode interferir na quantificaÃÃo da atividade antioxidante total. Portanto, este trabalho objetivou avaliar a influÃncia dos conservantes alimentares na atividade antioxidante total, na qualidade sensorial e microbiolÃgica de sucos tropicais de acerola. As frutas foram lavadas, sanitizadas (200mg/L de cloro ativo) e despolpadas, em seguida, formuladas com Ãgua e seus conservantes especÃficos. Os sucos foram tratados termicamente (90ÂC/60 segundos) e acondicionados a quente em garrafas de vidro, que foram fechadas, resfriadas atà 35ÂC e armazenadas à temperatura de 25ÂC por 180 dias. As formulaÃÃes testadas foram: suco controle, sem aditivo (C); suco com adiÃÃo de 0,004 g de metabissulfito de sÃdio/100 mL (SMS); suco com adiÃÃo de 0,08g sorbato de potÃssio /100 mL de (SSP); suco adicionado de 0,05g de benzoato de sÃdio /100 mL (SBS); suco com 0,002g de metabissulfito de sÃdio e 0,04 g/100 mL de sorbato de potÃssio/100 mL S(MS+SP)); suco com adiÃÃo de 0,002g/100 mL de metabissulfito de sÃdio e 0,025 g/100 mL de benzoato de sÃdio S(MS+BS). Foram realizadas determinaÃÃes quÃmicas de Ãcido ascÃrbico, carotenÃides totais, antocianinas totais, polifenÃis extraÃveis totais e quantificaÃÃo da atividade antioxidante total pelos mÃtodos ABTS e DPPH. Foi realizado o teste de esterilidade comercial nas amostras para determinar as condiÃÃes higiÃnico-sanitÃrias do processamento e verificar as possÃveis alteraÃÃes microbiolÃgicas. Os testes sensoriais de aceitaÃÃo foram utilizados nÃctares de acerola, preparados por diluiÃÃo a partir do suco tropical de acerola e adicionado de sacarose atà obtenÃÃo de 11 ÂBrix, os quais foram avaliados quanto aos atributos impressÃo global, cor, aparÃncia, aroma, doÃura, sabor e corpo utilizando uma escala hedÃnica estruturada de nove pontos. Os experimentos foram realizados em trÃs tempos (0, 90 e 180 dias) e realizados em triplicata. Os resultados foram tratados por anÃlise de interaÃÃo entre os diferentes tratamentos e tempo de armazenamento. Para o teor de antocianinas, todas as amostras apresentaram mÃdia de 1,0mg/100g (P>0,05). O teor de Ãcido ascÃrbico se manteve estÃvel durante o armazenamento, variando de 256,22 mg/100mL para o suco C, a 301mg/100mL, para os sucos SMS e SSP. Os teores de carotenÃides totais nos tratamentos com ou sem conservantes nÃo diferiram entre si (P>0,05), apresentando valor mÃdio de 0,04mg/100mL. Os flavonoides amarelos nÃo apresentaram diferenÃa significativa (P>0,05), apresentando mÃdia de 5,30mg/100mL. Para pigmentos escuros solÃveis o SMS obteve a menor variaÃÃo na absorbÃncia no tempo de 90 dias (0,170 a 0,240), e a maior variaÃÃo para o suco controle (0,230 a 0,320). Todas as amostras apresentaram perdas elevadas de fenÃlicos durante o armazenamento, observando-se perdas maiores entre 0 e 90 dias, que variaram de 36,59% para S(MS+BS) e 42,97% para SMS. Houve variaÃÃo significativa com o tempo para a atividade antioxidante total pelo ensaio DPPH (P≤0,05). Os valores variaram entre 877,41 e 978,44 g/g DPPH para os sucos C e SMS, respectivamente. Comportamento semelhante foi observado para os teores analisados pelo mÃtodo ABTS, observando-se para o SMS, 58,46 ÂM Trolox/g; e para o suco controle, 49,80 ÂM Trolox/g. A correlaÃÃo positiva e significativa foi verificada entre polifenÃis e o ensaio ABTS (r = 0,78) e para DPPH (r = 0,44). Antocianinas totais e ABTS (r = 0,39) e DPPH (r = 0,44). Os flavonÃides amarelos e os ensaios ABTS e DPPH se correlacionaram negativamente e significativamente (r = -0,83 e r= -0,52; respectivamente). NÃo foi observada interaÃÃo significativa entre os tratamentos e os tempos de armazenamento (P > 0,05). O metabissulfito de sÃdio e suas combinaÃÃes nÃo influenciaram na aceitaÃÃo sensorial dos nÃctares de acerola, com avaliaÃÃes dentro da faixa de aceitaÃÃo para todos os atributos analisados ao longo do tempo de armazenamento. Os aditivos sorbato de potÃssio e benzoato de sÃdio isoladamente contribuÃram para uma maior rejeiÃÃo sensorial dos produtos. Os conservantes quÃmicos utilizados, associados ao tratamento tÃrmico empregado, foram eficientes para a manutenÃÃo da esterilidade comercial dos sucos tropicais de acerola.

Thesis (M. Tech. Environmental health) -- Central University of technology, Free State, 2011 / Microbial pathogens play an important role in the food industry where they could cause disease and subsequently significant economic losses. Limited information is available on the situation with regard to Listeria in food products in South Africa. However, much research is being done in the rest of the world on Listeria indicating serious problems as a result of resistance development against various antimicrobial agents, including the organic acids. It is hypothesised that the situation with regard to resistance development may be more serious than generally admitted. Isolation of 200 different food samples was done by using a slightly modified EN ISO 11290-1/A1:2004 standard method. Identification of presumptive positive colonies was confirmed as Listeria by API (Analytical profile index) Listeria. API positive cultures were subjected to 16S rDNA sequencing to compare and confirm identification. Isolates and standard strains were screened for resistance to food preservatives such as organic acids and antibiotics used in the current treatment regime for Listeria infections. The organisms evaluated included isolated strains namely Listeria monocytogenes, Listeria welshimeri, Listeria innocua and their corresponding ATCC (American type culture colletion) strains. An agar dilution method as described by the Clinical and Laboratory Standard Institute (CLSI) was used to determine the minimum inhibitory concentrations (MICs) of 11 antibiotics and 13 organic acids and salts for all the isolates. Overall antibiotic susceptibility patterns of all the isolates indicated high level susceptibility to all the antibiotics tested. Susceptibility to all the organic acids was notably reduced at pH 7 in all the isolates and control strains. Eight highly susceptible strains were selected for induction and represented each of the species isolated. These isolates were exposed to increasing concentrations of three antibiotics and three organic acids. MICs were again determined for all the induced strains for five antibiotics and three organic acids. Proteins extracted from the induced strains were separated on discontinuous SDS-PAGE slab gels to generate total protein profiles. Notable variations were observed in MICs, although induction with antibiotics as well as organic acids did not result in general resistance development. However, evidence was provided that continuous exposure to antimicrobial agents may cause Listeria spp. to develop resistance to different antimicrobial agents. Further research and in depth studies on mechanisms involved in the development of resistance to food preservatives would, therefore, be required. Finally, it is concluded that Listeria monocytogenes may be a possible threat in the Central South African food industry, which deserves more attention. The situation may actually pose a problem that is overseen, because only a small percentage of people that get sick from food, would seek medical advice.