MILK PROTEIN FOULING IN A TUBULAR HEAT EXCHANGER: EFFECT OF MILK TEMPERATURE AND REYNOLDS NUMBER

In the present work, β-lactoglobulin fouling phenomenon was studied, when milk flowed in a tubular heat exchanger, where hot water was used to raise milk temperature. Experiments have been carried out to determine the effect of Reynolds number and fluid temperature in whey protein fouling, in a tubular heat exchanger and the results showed that fouling increases as the fluid temperature increases. In addition, as the Reynolds number increases, the total amount of fouling (obtained by integrating the whole amount of deposit down the tube dividing by the total area) decreased

Desempenho de bezerros aleitados com soro de queijo em associação ao colostro

O objetivo deste trabalho foi avaliar o desempenho de bezerros mestiços, aleitados com soro de queijo em associação ao colostro. Foram utilizados 24 bezerros Holandês x Zebu, distribuídos em delineamento inteiramente casualizado, com três tratamentos e oito repetições. Os tratamentos consistiram de: leite integral, 50% de leite integral + 50% de soro de queijo, e 30% de colostro + 70% de soro de queijo. O desenvolvimento dos bezerros foi avaliado até os 60 dias de idade, por meio de pesagens semanais e mensurações corporais. Para a estimativa de consumo, foram feitas medições diárias de consumo da dieta sólida, pelo método oferta/sobra. O desempenho econômico foi avaliado pelo cálculo de indicadores de custos e receitas, e de medidas de resultados econômicos. Não houve influência da dieta líquida sobre o consumo de matéria seca e sobre as médias de medidas corporais dos bezerros. Foram observadas diferenças significativas no ganho de peso dos animais na segunda e na quarta semanas de vida. A dieta com colostro apresentou o maior lucro adicional em comparação ao tratamento controle. A associação do soro de queijo ao colostro é a opção mais vantajosa economicamente, já que a substituição de 100% do leite por esses subprodutos não prejudicou o desempenho dos animais

A Comparative Study Between Ovalbumin And β-lactoglobulin Fouling In A Tube Hot Surface

In the present work, Ovalbumin and β-lactoglobulin fouling phenomenon was studied, when white egg and milk flowed in the inner tube of a double tube heated by hot water which flows in the ring space between them. The fouling kinetics depends on the mass transfer effects, which is a function of protein solubility. To describe the fouling kinetics a calculus algorithm was developed, having as subsidy the protein solubility itself. The proteins solubility curves have been taken by previous works. Results showed that ovalbumin fouling was slower than β-lactoglobulin and the time necessary for the tube's inner radius to decrease in 30% of the original radius was smaller for high temperatures, for both proteins. Besides, both ovalbumin and β-lactoglobulin deposition was greater at the tube's entrance than in its exit. Therefore, the radius reduction was faster in that area. © 2005 Elsevier Ltd. 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BrazilJeurnink, T.J.M., Verheul, M., Stuart, M.A.C., Kruif, C.G., Relation between the denaturation and fouling behaviour of β-lactoglobulin (1996) Heat Treatments & Alternative Methods, pp. 73-82. , BrusselsKong, J.Y., Miyawaki, O., Nakamura, K., Yano, T., The "intrinsic" thermal conductivity of adds wet proteins in relation to their average hydrophobicity:analyses on gels of egg-albumin, wheat gluten and milk casein (1982) Agricultural and Biological Chemistry, 46 (3), pp. 789-794Lalande, M., Tissier, J.P., Corrieu, G., Fouling of the plate heat exchanger used in ultra-high-temperature sterilisation of milk (1984) Journal of Dairy Research, 51 (4), pp. 557-568Ling, A.C., Lund, D.B., Fouling of heat transfer surfaces by solutions of egg albumin (1978) Journal of Food Protection, 41 (3), pp. 187-194Lund, D.B., Bixby, D., Fouling of heat exchange surfaces by milk (1975) Process Biochemistry, 10 (9), pp. 52-55Mine, Y., Effect of pH during the dry heating on the gelling properties of egg 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Efecto de la temperatura sobre las proteínas de lactosuero

In the present work, whey protein fouling phenomenon was studied, when fowed in the inner tube of a double tube heated by hot water which fows in the ring space between them. The fouling kinetics depends on the mass transfer effects, which is a function of protein solubility. To describe the fouling kinetics a calculus algorithm was developed, having as subsidy the protein solubility itself. The proteins solubility were determined in a separate investigation. Results showed that the time necessary for the tube´s inner radius to decrease in 30% of the original radius was smaller for high temperatures. Besides, whey protein deposition was greater at the tube´s entrance than in its exit. Therefore, the rate of radius reduction was faster in that area. The experimental check for the algorithm was conducted in a pilot plant.El presente trabajo es un estudio del fenómeno de incrustación de la proteína del suero de leche al interior de un intercambiador de calor por donde fuye agua caliente por entre los dos tubos. La cinética de incrustación depende de los efectos de la transferencia de masa, que es una función de la solubilidad de las proteínas. Para describir la cinética de incrustación de las proteínas se desarrolló un algoritmo de cálculo dependiente de la solubilidad. La solubilidad de la proteína fue determinada en una investigación por separado. Los resultados mostraron que el tiempo necesario para que el tubo de radio interior disminuyera en un 30% de la radio original fue menor para altas temperaturas. Además, la deposición de las proteínas de suero de leche fue más intensa en la entrada que en la salida. Por lo tanto, la tasa de reducción de radio fue más rápido en esa zona. El experimento para comprobar el algoritmo se llevó a cabo en una planta piloto