Eliminating calcium chloride and replacing whole casein with k-casein eliminated clouding and sharpened diffusion boundaries in casein-agar gels used for the estimation of residual milk clotting enzymes in curd and whey. It also eliminated the need for a highly purified calcium-free agar. The substrate contained .54 percent k-casein, 3.6 percent sodium acetate, .73 percent bacto-agar and 95.13 percent water. The pH was adjusted to 5.9 with .lN hydrochloric acid. Proteases derived from Mucor pusillus var Lindt, Mucor Miehei and Endothia parasitica, as well as rennet, procine and bovine pepsins were used at recommended levels to set milk for Cheddar cheese manufacture. Whey samples from each lot were taken at draining and adjusted to pH 5.2, 5.6, 6.0, 6.2, 6.6 and 7.0 prior to being heated to 68.3C, 71.1C and 73.9C for .25, .5, 1, 5, and 10 minutes. Enzyme activities were assayed before and after heating. Mucor miehei protease was the most heat stable at all pH values followed by Mucor pusillus protease, rennet, bovine pepsin, E. parasitica protease and porcine pepsin. The heat stability of all enzymes except E. parasitica protease decreased with increasing pH, E. parasitica protease decreased with decreasing pH. All enzymes were inactivated at the minimum heat treatment at pH 7.0 except E. parasitica protease which was most stable at that pH. At pH 5.2 M. miehei protease persisted after a 10 minute treatment at 73.9C.

Made available in DSpace on 2016-05-02T13:54:22Z (GMT). No. of bitstreams: 1 AlanAndradeMesquita-dissertacao.pdf: 164106 bytes, checksum: 3b73915b95c788017b359efc06ba110b (MD5) Previous issue date: 2012-06-20 / The objective of this study was to evaluate whether oxytocin, before and after milking, influences the efficiency of milk ejection, and consequently increased production and changes in milk composition. The experiment was conducted at the Federal Institute of Education, Science and Technology in Southern Minas Gerais - Machado Campus in the cattle industry, using 39 animals, divided into 13 blocks, each with three animals listed from "1" to "13". The division of animals was based on the sequence of individual production, so that block "1" was composed by the three most productive animals and block "13" by three animals of lower production. For each block, the animals were randomly assigned to treatments 1, 2 and 3. One (T1) animal did not receive oxytocin, representing the control treatment. It received only normal saline 0.5 ml, in the entire teat during the 60 days of the experiment. In two treatment (T2), all the animals received milking oxytocin at a concentration of 10 IU, total 0.5 ml, before the start of milking, during the 60 days period. In treatment three (T3), the animals received oxytocin at the end of milking at a concentration of 10 IU, total of 0.5ml, and were milked again. Such activities were performed during the 60 days of the experiment. To measure the production of cow s milk meters were used and sampling was performed every 15 days, totaling four weighing and sampling procedures. After measured the production of all animals were, measured samples were collected and sent for analysis. The variables analyzed were the acidity of the milk and quantified of the composition of fat, lactose and protein. The results were submitted to ANOVA and subsequently the comparison of means test, which was statistically significant at 5%. According to the results oxytocin did not influence milk production, the average percentage of fat, lactose and milk protein, but enabled moderation of declining production in the lactation curve and may decrease the effect of the fall in the percentage of protein in milk. / O objetivo deste trabalho foi avaliar se a ocitocina, antes e após a ordenha, influencia a eficiência da ejeção do leite e consequentemente o aumento da produção e mudanças na composição do leite. O experimento foi realizado no Instituto Federal de Educação, Ciência e Tecnologia do Sul de Minas Gerais - Câmpus Machado, no setor de bovinocultura, utilizando 39 animais, divididos em 13 blocos, cada um com três animais enumerados de 1 a 13 , e foi utilizado na divisão dos animais, uma sequência de produção individual. Assim, o bloco 1 foi composto pelos três animais mais produtivos, e o bloco 13 , pelos três animais de menor produção. Em cada bloco os animais foram sorteados para os tratamentos 1, 2 e 3, sendo que no tratamento um (T1) os animais não receberam ocitocina, representando o tratamento controle, apenas recebendo 0,5ml de soro fisiológico, em todas as ordenhas, durante os 60 dias do experimento. No tratamento dois (T2) os animais receberam ocitocina em todas as ordenhas, na concentração de 10 UI, no total de 0,5 ml, antes do início da ordenha, durante os 60 dias do experimento. No tratamento três (T3) os animais, receberam ocitocina no final de ordenha, na concentração de 10 UI, no total de 0,5 ml e foram reordenhados, atividades essas realizadas durante os 60 dias do experimento. Para aferir a produção das vacas, foram usados medidores de leite, e as colheitas de amostras foram realizadas a cada 15 dias, totalizando quatro procedimentos de pesar e amostrar. Após aferido a produção de todos os animais, as amostras foram coletadas e encaminhadas para as análises. As variáveis analisadas foram a acidez do leite, e após a determinação da acidez, quantificou-se a composição de gordura, lactose e proteína. Os resultados foram submetidos à análise de variância e posteriormente, ao teste de comparação de médias, com diferença estatística significativa de 5%. De acordo com os resultados, a ocitocina não influência a produção leiteira, nas médias de porcentagem de gordura, lactose e proteína do leite, mas possibilita a moderação da queda de produção na curva de lactação e pode diminuir o efeito da queda da porcentagem de proteína na lactação.