Call number: LD2668 .T4 1986 M37 / Master of Science / Human Nutrition

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / O objetivo deste estudo foi verificar o efeito do Ãcido acÃtico 1% sobre a microbiota da carne ovina maturada. Foram utilizados 5 animais ovinos machos castrados do tipo Sem RaÃa Definida (SRD), com idade aproximada de 1 ano, provenientes do interior do estado do CearÃ. ApÃs o abate as carcaÃas dos animais foram refrigeradas por 12 horas a 0ÂC e em seguida foram coletadas amostras da superfÃcie dos seguintes locais: paleta, pescoÃo, peito, lombo, coxÃo e cavidade abdominal. Nessas amostras foram realizadas anÃlises microbiolÃgicas de contagem padrÃo em placas de bactÃrias mesÃfilas, pesquisa de coliformes totais e fecais. As paletas foram entÃo retiradas das carcaÃas e cortadas em fatias de peso similar, da porÃÃo proximal para a porÃÃo distal desse corte. As fatias das paletas direitas foram submetidas a tratamento de imersÃo em soluÃÃo de Ãcido acÃtico a 1% por 1 minuto e as fatias esquerdas foram imersas em Ãgua potÃvel (controle). Todas as fatias foram em seguidas embaladas individualmente à vÃcuo em filme flexivel, impermeÃvel ao oxigÃnio e armazenadas para maturaÃÃo a 1ÂC. Para as anÃlises microbiolÃgicas da carne de paleta, foram coletadas fatias nos dias 3, 13, 23, 33 e 48 de armazenamento. Em cada dia foram coletadas fatias, sendo 5 de cada tratamento de imersÃo. As anÃlises realizadas foram contagem padrÃo em placa (mesÃfilos e psicrofilos), contagem de bolores e leveduras, contagem de clostridios sulfito-redutores, pesquisa de coliformes totais e fecais e pesquisa de Salmonella. NÃo houve diferenÃas significativas (P>0,05) na contagem de bactÃrias entre os diferentes locais da carcaÃa ovina analisada. Em relaÃÃo ao estudo de armazenamento da carne, foi observada uma reduÃÃo (P<0,05) da contagem de bactÃrias mesÃfilas nas carnes tratadas com Ãcido nos dias 13 e 23 de estocagem. Com 3 e 13 dias de armazenamento houve uma reduÃÃo significativa (P<0,05) na microbiota de psicrÃfilos na carne da paleta ovina tratada com Ãcido. Entretanto nos dias 23, 33 e 48 de armazenamento esse comportamento nÃo foi observado. Em relaÃÃo a bolores e leveduras, houve uma reduÃÃo (P<0,05) da microbiota das amostras tratadas em relaÃÃo a das nÃo tratadas. Este efeito foi evidente atà o dia 13 de armazenamento. Somente no 3 dia de armazenamento, as amostras tratadas apresentaram contagens de coliformes totais significativamente (P<0,05) menores que as nÃo tratadas. Tal comportamento, porÃm, nÃo foi verificado nos dias 13, 23, 33 e 48 de estocagem. As amostras tratadas com Ãcido acÃtico 1% apresentaram valores menores (P<0,05) de coliformes fecais do que as nÃo tratadas. Observou-se ausÃncia de clostrÃdios sulfito-redutores em todas as amostras, independente do tratamento e do tempo de maturaÃÃo. A pesquisa de Salmonella, indicou presenÃa deste microrganismo em 20 e 24%, das amostras tratadas com Ãcido acÃtico 1% e nÃo tratadas, respectivamente. Os valores de pH foram significativamente menores (P<0,05) nos dias 3, 23 e 33 que nos dias 13 e 48 de armazenamento. Os resultados sugerem que o abate cuidadoso de animais ovinos nas condiÃÃes ambientais do Nordeste Brasileiro, permite obter carcaÃas com nÃveis aceitÃveis de microrganismos na superfÃcie. A imersÃo das carnes em Ãcido acÃtico 1% seguida de estocagem a vÃcuo permite manter as carnes refrigeradas (1ÂC) por 13 dias, com controle eficiente da microbiota deteriorativa, mantendo um padrÃo higiÃnico-sanitÃrio adequado, mas nÃo à suficiente para inibir o crescimento de Salmonella. / The objective of this study was to verify the effect of 1% acetic acid on the microbial condition of aged lamb meat. The experiment used five undefined breed (SRD) wethers, with 1 year of age. After slaughter the carcasses were chilled at 0ÂC and kept for 12 h. Samples for microbiological analysis were collected from the surface of shoulder, neck, breast, loin, leg and the ventral side of the flank. These surfaces were evaluated for mesophiles and total and fecal coliform microrganisms. Shoulders were then separated from the carcass and cut to standard weight slices, from the proximal to the distal region of the cut. The right side shoulder slices were dipped in 1% acetic acid solution for 1 min and the left side shoulder slices were dipped in distilled water (control). The slices were individually vacuum packaged in a film, with low permeability to oxygen and then stored at 1ÂC. On days 3, 13, 23, 33 and 48 of the aging period samples (5 trated with 1% acetic acid and 5 control) were collected, to be analyzed for total plate count, mould and yeast, sulfite-reduzing clostridia, total and fecal coliforms and Salmonella. There was no difference (P>0.05) in surface microrganism counts among different locations in the lamb carcass. Related to the aging of meat trated with acetic acid it was observed a decrease (P<0.05) in mesophiles count on trated samples with 13 and 23 days of aging. At 3 and 13 days of aging occurred a significant (P<0.05) decrease of psicrophylic organisms in meats treated with acetic acid. However at 23, 33 and 48 days of storage this effect was not observed. There were a decrease (P<0.05) in moulds and yeast counts is samples treated with acid. Mould andyeast counts were smaller (P<0.05) at day 13 than those at days 33 and 48 days of aging. Only at day 3 of aging treated samples showed lower (P<0.05) total coliform counts than samples with no acid. Meat samples treated with 1% acetic acid showed lower (P<0.05) fecal coliform counts than samples with no acid. It was observed absence of sulfite-reduzing clostridia in all samples independent of acid treatment or aging time. The presence of Salmonella detected in 20% of the treated samples and in 24% of the untreated ones. Meat pH values were lower (P<0.05) on days 3, 23 and 33 than on days 13 and 48 of aging. Results suggest that proper slaughter conditions in Northeast Brasil produce lamb carcasses with acceptable counts of microrganisms. Deeping of meat cuts in 1% acetic acid solution followed by vacuum packazing is appropriate to age meat at 1ÂC for 13 days. This treatment keeps low levels of psicrofilic counts, allows a sound higienic condition of the meat but it is not enough to inhibit the presence of Salmonella.

Thesis (MSc. (Microbiology)) --University of Limpopo, 2018 / Refer to the document / National Research Foundation (NRF)

The aerobic transformation of TCE and cis-DCE by a tetrabutoxysilane-grown microorganism (Vancheeswaran et al., 1999) led to the investigation of novel substrates, including benzyl alcohol, for promoting cometabolism. The culture grew on carboxylic compounds and alcohols, but did not grow on formate, methanol, methane, propane, butane, ethylene, benzene, toluene, or p-xylene. Cis-DCE transformation was observed when the culture grew on butyrate, glucose, 1-propanol, 1-butanol, ethanol, benzyl alcohol, and phenol, and effectively transformed TCE, cis-DCE, and vinyl chloride when grown on phenol or benzyl alcohol. Several cycles of growth on benzyl alcohol led to increases in TCE transformation rates and transformation capacities. Products of benzyl alcohol degradation shifted from benzaldehyde to 2-hydroxy benzyl alcohol (2HBA) during the several cycles of growth. In resting cells studies, 2HBA production rates were highly correlated with TCE transformation rates. TCE transformation and 2HBA production rates doubled when the culture was grown on phenol and rates of TCE transformation were correlated with 2HBA production rates. Benzyl alcohol- and phenol-grown cells oxidized toluene to o-cresol, which indicated the similarity between benzyl alcohol ortho-monooxygenase, phenol hydroxylase, and toluene ortho-monooxygenase. 2-Butyne and 1-hexyne (but not acetylene) inhibited benzyl alcohol- and phenol-grown cells similarly, indicating the same ortho-monooxygenase was responsible for TCE cometabolism. Resting cell kinetic studies were performed with cells grown on phenol or benzyl alcohol. Benzyl alcohol degradation followed a Monod kinetics while phenol degradation followed a Haldane kinetics. The maximum transformation rates (k[subscript max]) of TCE, cis-DCE, and VC achieved by phenol-grown cells were about a factor of two higher than achieved with benzyl alcohol-grown cells, while the half-saturation constants (K[subscript s]) were in a similar range. Transformation capacities (Tc) for TCE, cis-DCE, and VC were about a factor of two to four higher with phenol-grown cells. The modeling of TCE, cis-DCE, and VC transformation using independently measured k[subscript max] and K[subscript s] values matched well with observed data from batch tests. Benzyl alcohol was shown to be an effective novel substrate for the aerobic cometabolism of TCE, cis-DCE, and vinyl chloride. Being a non-regulated compound, it might have applications for in-situ bioremediation. / Graduation date: 2004

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Thesis (Ph. D.)--School of Chemistry and Biochemistry, Georgia Institute of Technology, 2004. Directed by Suzanne B. Shuker. / Includes bibliographical references.

Thesis (Ph. D.)--Mississippi State University. Department of Civil Engineering. / Title from title screen. Includes bibliographical references.

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