Avaliação das características físico-químicas e alterações do leite UHT (UAT) produzido no Estado de Goiás ao longo da estocagem
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2010-05-14
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Universidade Federal de Goiás
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With the objective of evaluating the physical/chemical, microbiological characteristics and the changes that occur in UHT milk (UAT) processed in the State of Goias during its storage for 135 days, a study was done between August and December 2008 with all the companies that produced UHT milk (UAT) processed in the State. Samples were collected from refrigerated raw milk stored in milk storage silos of industry for analysis of their physical/chemical and microbiological characteristics. From each company, twelve one liter cartons of milk were collected for analysis of their physical/chemical and microbiological properties as well as nitrogen compounds and the amount of fat separation from the milk and sedimentation within each sample. The samples were sent to the laboratories of Microbiology and Dairy of the School of Agronomy and Food Engineering at the Federal University of Goias (UFG). The physico-chemical properties of raw milk were in accordance with the parameters established by legislation, except for three brands of milk, with values of freezing point, nonfat milk solids and total solids. The Alizarol test results were normal for UHT milk (UHT) of all brands, except the milk of the mark "E", which has had worst results established by legislation. All milk samples were within the standards for titratable acidity and pH. The density indices were normal, but decreased during the stock. The freezing point values were within the standards, but increased during the storage and the values of total solids and nonfat solids were low and at variance with the laws in UHT milk (UHT) of all brands. The fat found below the minimum content of 3% recommended by the legislation. All results are suggestive of water being added accidentally during processing. Scores were found higher than those established by law for psychotropic and mesophilic aerobic refrigerated raw milk. In UHT milk (UHT) milk from only one mark was at odds as the parameters established by law for heat resistant spores of aerobic mesophiles. It was verified a progressive increase in sedimentation and fat separated from milk during storage and observed age gelation in milk from one brand to 135 days of storage. From the results obtained can be verified that the physicochemical characteristics of UHT milk (UAT), when compared to raw milk source, changed negatively and that the raw material, the type of thermal processing and storage time at room temperature are possible causes for the changes that occurred throughout the shelf-life UHT milk (UAT).
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COSTA, Andréia Di Martins Carmo. Avaliação das características físico-químicas e alterações do leite UHT (UAT) produzido no Estado de Goiás ao longo da estocagem. 2010. 56 f. Dissertação (Mestrado em Ciencias Agrárias - Agronomia) - Universidade Federal de Goiás, Goiânia, 2010.