Tecnologia de Alimentos
URI permanente desta comunidadehttps://locus.ufv.br/handle/123456789/11783
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Item Estudo da viscosidade de soluções proteicas através do analisador rápido de viscosidade (rva)(Revista Instituto de Laticínios Cândido Tostes, 2014-02-14) Alves, Maura P.; Perrone, Ítalo T.; Souza, Alisson Borges de; Stephani, Rodrigo; Pinto, Cláudia Lúcia de Oliveira; Carvalho, Antônio F. deEste trabalho objetivou determinar pelo analisador rápido de viscosidade (RVA) as curvas de viscosidade de soluções preparadas a partir de concentrados proteicos de soro (CPSs) e determinar o tempo ideal de tratamento térmico visando à obtenção da viscosidade máxima nesta etapa. Os CPSs, produzidos a partir de amostras de soro submetidas inicialmente a tratamentos térmicos e de microfiltração, apresentaram composição centesimal compatível com padrões internacionais com diferença significativa (p<0,05) entre as amostras apenas para o teor de gordura. Pela análise dos perfis viscográficos observou-se que os CPSs produzidos a partir de soro microfiltrado apresentaram valores de viscosidade mais altos que aqueles submetidos ao tratamento térmico para todos os dados coletados. Além disso, o tempo ideal de tratamento térmico das soluções de CPSs visando maximizar a viscosidade durante o aquecimento foi de, aproximadamente, 10 minutos. Os resultados possibilitam a aplicação dos CPSs pelas indústrias alimentícias considerando a característica desejada no produto final, sendo que o RVA mostrou-se uma ferramenta apropriada para estudo de funcionalidade desses concentrados.Item Role of structural ions on the dynamics of the Pseudomonas fluorescens 07A metalloprotease(Food Chemistry, 2019-07-15) Alves, Maura P.; Eller, Monique R.; Carvalho, Antonio Fernandes de; Ligabue-Braun, Rodrigo; Polêto, Marcelo D.The molecular dynamics of the Pseudomonas fluorescens 07A metalloprotease in the presence of structural Ca2+ and Mn2+ ions was evaluated. Seven Ca2+ ions are primarily bound to the C-terminus, while a divalent cation is located at the catalytic site, acting as a cofactor. The observed enzyme’s experimental activity suggests that Mn2+ could compete for the active site of the enzyme with Ca2+, Zn2+ or other divalent cations, thus providing greater catalytic power to the enzyme. Our molecular dynamics simulations suggest that these ions partially protect the enzyme’s structure from thermal denaturation. Moreover, our simulations have shown a collective movement of opening-closing of the active-site in simulations with structural Ca2+ and Mn2+ ions bound, leading to a proposal of a dynamical model of P. fluorescens 07A metalloprotease active and inactive conformations. These findings can support the development of measures to control the activity of P. fluorescens and other spoilage microorganism proteases.Item Temperature modulates the production and activity of a metalloprotease from Pseudomonas fluorescens 07A in milk(Journal of Dairy Science, 2018-02) Alves, Maura P.; Salgado, Rafael L.; Eller, Monique R.; Dias, Roberto Sousa; Paula, Sérgio Oliveira de; Carvalho, Antonio Fernandes deThis work evaluated the expression and activity of a metalloprotease released by Pseudomonas fluorescens 07A in milk. Low relative expression of the protease by the strain was observed after incubation for 12 h at 25°C while the strain was in the logarithmic growth phase. After 24 h, protease production significantly increased and remained constant for up to 48 h, a time range during which the strain remained in the stationary phase. Conversely, at refrigeration temperatures, at 12 h the strain was still in the lag phase and expressed the protease at higher levels than when the logarithmic phase was reached. Casein fractions were highly degraded by P. fluorescens 07A, the purified protease, and the bacterial pellet on d 7 of incubation at 25°C and to a lesser extent at 10°C for the sample incubated with the bacterium. Heat treatment at 90°C for 5 min completely inactivated the proteolytic activity of the purified protease and the bacterial pellet. This work contributes to the knowledge about the conditions of milk storage that influence the production and activity of this extracellular metalloprotease. The results demonstrate the need to find alternative strategies to control the synthesis and activity of proteolytic enzymes in the dairy industry to ensure the quality of processed products.