Orientador: Antonio Nader Filho / Banca: Angela Cleusa de Fatima Banzatto de Carvalho / Banca: Luiz Francisco Zafalon / Resumo: O leite é um alimento altamente nutritivo e excelente substrato para a multiplicação de microrganismos. Os estafilococos estão entre os principais contaminantes do leite, seja em decorrência da mastite ou de falhas de higienização. A contaminação do leite pode favorecer a adesão bacteriana sobre superfícies com a formação de biofilmes, cujos fragmentos podem se desprender e contaminar o produto durante o processo de beneficiamento, o que representa um risco à saúde do consumidor. Tendo isto em foco, objetivou-se o presente estudo, em uma micro-usina do Estado de São Paulo, a fim de investigar a presença e formação de biofilme por Staphylococcus spp, antes e após o processo de higienização. Colheu-se o total de 60 amostras por meio de suabes, antes e após o processo de higienização, das superfícies do tanque de recepção, do tanque de estocagem de leite cru, da tubulação de saída do pasteurizador, do tanque de estocagem de leite pasteurizado, e da tubulação da máquina de envase. Foram colhidas, ainda, amostras de leite no tanque de recepção, no tanque de estocagem de leite cru, na tubulação de saída do pasteurizador e amostras de leite envasado, assim como das embalagens plásticas vedadas e vazias, utilizadas para o envase do leite pasteurizado. Dentre 41 estirpes de Staphylococcus spp isoladas, 16 (39,0%) mostraram-se positivas na prova da coagulase, enquanto que 25 (61,0%) foram negativas. Por meio de análise genotípica, com a técnica de Reação em Cadeia da Polimerase (PCR), pode-se observar que, dentre as 16 estirpes coagulase positivas, quatro (25%) apresentavam o gene icaA e 16 (100%) possuíam o gene icaD. Dentre as 25 estirpes coagulase negativas, 11 (44%) possuíam o gene icaA e 25 (100%) possuíam o gene icaD. Visualizou-se, por meio da microscopia eletrônica de varredura... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Milk is a highly nutritious food and excellent substrate for the multiplication of microorganisms. Staphylococci are one of the major contaminants of milk whether due to mastitis or hygiene failures in cleaning. Milk contamination may encourage bacterial adherence on surfaces with the formation of biofilms, whose fragments can detach and contaminate the product during beneficial processing, which represents a health risk to the consumers. With this in focus as the objective of this present study, to investigate the presence and formation of biofilm of Staphylococcus spp before and after the cleaning process in a micro-dairy plant in São Paulo State. A total of 60 swab samples were collected before and after the cleaning process from the reception tank surfaces, the raw milk storage tank storage, the pasteurizer outlet pipe, the pasteurized milk storage tank, and the filling machine. Further samples were collected of the milk in the receiving tank, the raw milk storage tank, from the pasteurizer outlet pipe, and packaged milk, as well as the empty sealed plastic packaging used for packaging the pasteurized milk. Of the 41 strains of isolated Staphylococcus spp, 16 (39.0%) indicated positive in the coagulase test, while 25 (61.0%) were negative. Through genetic analysis, using the Polymerase Chain Reaction (PCR) technique, it was observed that within the 16 strains of coagulase-positive, four (25%) presented the gene icaA and 16 (100%) had the gene icaD. Of the 25 strains of coagulase-negative, 11 (44%) had the gene icaA and 25 (100%) had the gene icaD. It was seen using a scanning electron microscope the start of bacteria adhesion and the formation of biofilm for all the isolated strains. From the obtained results it was possible to see evidence to the potential risk to the health of the consumer represented... (Complete abstract click electronic access below) / Mestre

The diploma thesis is dealing with design of analytical method for determination of caseins in cow‘s milk. Capillary electrophoresis was used as separative method. The developed procedure was verified on real samples. Theoretical part gives basic information about caseins. Their chemical and physical properties, structure, way of manufacturing, usage in food industry and non-food applications are described. There are further some nutritional factors mentioned, whose application in cattle nutrition can affect milk composition, especially milk protein concentration. Literary part contains summary of capillary electrophoresis methods used for casein determination. Experimental part describes used separative system, procedure of casein isolation from milk and casein content in individual milk samples. Separation of milk caseins was performed in an untreated fused-silica capillary with dimensions of 50 um i.d. x 96 cm total length (71 cm effective length). Phosphate buffer (10 mM, pH 2,5) served as the background electrolyte. Casein from milk was obtained by isoelectric precipitation at pH 4,6 after adding 10% acetic acid. Product was washed with acetone to remove fat and dried. Total casein yield was the highest in bio-milk (27,04 g/l), the lowest in skim long-life milk (22,04 g/l). The diploma thesis has arisen on the basis of cooperation of Institute of Food Science and Biotechnology, Faculty of Chemistry, Brno University of Technology and Research Institute for Cattle Breeding, Ltd., Department of Animal Nutrition Physiology in Pohořelice.

The diploma thesis, Determination of the caseins by the capillary electrophoresis, is dealing with a creating of the analytical method for a determination of the caseins in cow‘s milk. The capillary electrophoresis was used as a separative method. The developed procedure was optimalized and verified on standards of the caseins and the real samples. The theoretical part gives an information about the compound of cow's milk, caseins, their usage in the food industry and the non-food technologies. There are mentioned some further nutritional factors, whose application in the cattle nutrition can affect the milk composition. The experimental part describes the procedure of the caseins isolation from milk, the used separative system and the determination of the caseins in the lyophilisated samples of milk. The separation was performed in two untreated fused-silica capillaries. Both of them had the same internal diameter: 50 m. The total length of the first capillary was 96 cm (71 cm of effective length) and of the second used capillary 125 cm (effective length 100 cm) The phosphate buffer (10 mM, pH 2,5) served as a basic electrolyte. The diploma thesis has arisen on the basis of the cooperation of the Institute of Food Science and Biotechnology, the Faculty of Chemistry, Brno University of Technology and the Research Institute for Cattle Breeding, Ltd., Department of Animal Nutrition Physiology in Pohořelice.