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This work aimed at evaluating the influence of enzyme concentration, temperature, and reaction time in the lactose hydrolysis process in milk, cheese whey, and whey permeate, using two commercial β-galactosidases of microbial origins. We used Aspergillus oryzae (at temperatures of 10 and 55°C) and Kluyveromyces lactis (at temperatures of 10 and 37°C) β-galactosidases, both in 3, 6, and 9 U/mL concentrations. In the temperature of 10°C, the K. lactis β-galactosidase enzyme is more efficient in the milk, cheese whey, and whey permeate lactose hydrolysis when compared to A. oryzae. However, in the enzyme reaction time and concentration conditions evaluated, 100% lactose hydrolysis was not reached using the K. lactis β-galactosidase. The total lactose hydrolysis in whey and permeate was obtained with the A. oryzae enzyme, when using its optimum temperature (55°C), at the end of a 12 h reaction, regardless of the enzyme concentration used. For the lactose present in milk, this result occurred in the concentrations of 6 and 9 U/mL, with the same time and temperature conditions. The studied parameters in the lactose enzymatic hydrolysis are critical for enabling the application of β-galactosidases in the food industry.

The aim of this work was to evaluate the effects of pasteurization and ultra-high temperature processes on proximate and physicochemical composition, microbiological parameters and fatty acid profile in bovine milk. Raw, pasteurized and sterilized milks were collected at a dairy factory in the state of Rio Grande do Sul, Brazil. The samples were submitted to determination of moisture, protein, total fat, lactose, total solids, free-fat dry extract, urea, calcium, phosphorus, pH, acidity, density, fatty acid profile, somatic cell count and total bacterial count. Pasteurized and ultra-high temperature milks kept protein and lactose content similar to raw milk. Pasteurization and sterilization altered the composition of the milk slightly, decreasing total fat and total solids and increasing urea. These processes changed essentiality short-chain fatty acids (4:0, 6:0 and 8:0). High proportions of palmitic acid (18:0), oleic acid (18:1 n-9), stearic acid (18:0) and myristic acid (14:0) were found in all milks analyzed. The absence of large significant modifications on milk composition and fatty acid profile indicates that the processes could be applied without altering the nutritional value of the milk.

RESUMOO Rio Grande do Sul é um dos maiores produtores de leite do país e o Vale do Taquari contribui com aproximadamente 7% da produção do estado. O queijo e a ricota são alguns dos principais derivados do leite produzidos na região, que geram nos seus processos de fabricação quantidades elevadas de soros de queijo e de ricota, respectivamente. Por sua elevada carga orgânica, estes soros devem ser tratados antes do lançamento em corpos hídricos. No entanto, estudos indicam que esses subprodutos podem ser reaproveitados. Portanto, o objetivo desse trabalho foi avaliar as características físico-químicas de soros de queijo e de ricota coletados em uma indústria de laticínios do Vale do Taquari visando ao aproveitamento na elaboração de novos produtos alimentícios. As amostras foram submetidas às determinações de acidez, pH, cinzas, umidade, proteínas, gordura, demanda química de oxigênio, carbono e nitrogênio total e lactose. Os parâmetros avaliados apresentaram variações, provavelmente em função dos soros serem provenientes de processos de fabricação de diferentes tipos de queijo e de ricota. Além disso, o soro de queijo apresentou maior carga orgânica. As concentrações de proteínas e lactose dos soros indicam que estes podem ser reaproveitados no desenvolvimento de novos produtos e processos. Palavras-chave:Leite. Derivados Lácteos. Subprodutos. ABSTRACTThe Rio Grande do Sul is one of the largest milk producers in the country and Taquari Valley contributes about 7% of the state production. Cheese and ricotta are some of the major dairy products produced in the region, which generate in their manufacturing processes large amounts of cheese whey and ricotta whey, respectively. Because of the high organic load they should be treated before being released into water bodies. However, studies indicate that these by-products can be reused. Therefore, the aim of this study was to evaluate the physicochemical characteristics of ricotta and cheese whey collected in a dairy industry in the Taquari Valley in order to use it in the development of new food products. The samples were processed for determination of acidity, pH, ash, moisture, protein, fat, chemical oxygen demand, total carbon and nitrogen, and lactose. The parameters showed variations, probably because the whey was from the manufacturing processes of different types of cheese and ricotta. Furthermore, the cheese whey showed a higher organic load. The protein and lactose

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