RESUMO
Assessment of sustainability will become more relevant for the food industry in the years to come. Analysis based on exergy, including the use of exergetic indicators and Grassmann diagrams, is a useful tool for the quantitative and qualitative assessment of the efficiency of industrial food chains. In this paper, we review the methodology of exergy analysis and the exergetic indicators that are most appropriate for use in the food industry. The challenges of applying exergy analysis in industrial food chains and the specific features of food processes are also discussed.
Assuntos
Eficiência Organizacional , Indústria Alimentícia/métodos , Qualidade dos Alimentos , Abastecimento de Alimentos/economia , Saúde Global , Modelos Econômicos , Avaliação de Programas e Projetos de Saúde , Animais , Eficiência Organizacional/economia , Indústria Alimentícia/economia , Indústria Alimentícia/tendências , Alimentos em Conserva/análise , Alimentos em Conserva/economia , Indústria de Processamento de Alimentos/economia , Indústria de Processamento de Alimentos/métodos , Indústria de Processamento de Alimentos/tendências , Saúde Global/economia , Humanos , Resíduos Industriais/economia , Resíduos Industriais/prevenção & controle , Valor Nutritivo , Avaliação de Programas e Projetos de Saúde/economia , Energia Renovável , TermodinâmicaRESUMO
Many ß-galactosidases show large differences in galacto-oligosaccharide (GOS) production and lactose hydrolysis. In this study, a kinetic model is developed in which the effect of lactose, glucose, galactose, and oligosaccharides on the oNPG converting activity of various ß-galactosidases is quantified. The use of oNPG as a competing substrate to lactose yields more information than can be obtained by examining only the conversion of lactose itself. The reaction rate with lactose or oligosaccharides as substrate relative to that with water as acceptor is much higher for the ß-galactosidase of Bacillus circulans than the bgalactosidases of Aspergillus oryzae and Kluyveromyces lactis. In addition, the ß-galactosidase of B.circulans has a high reaction rate with galactose as acceptor, in contrast to those of A. oryzae and K. lactis. The latter two are strongly inhibited by galactose. These differences explain why ß-galactosidase of B. circulans gives higher yields in GOS production than other ß-galactosidases. Many of the reaction rate constants for the ß-galactosidase isoforms of B. circulans increase with increasing molecular weight of the isoform. This indicates that the largest isoform ß-gal-A is most active in GOS production. However, its hydrolysis rate is also much higher than that of the other isoforms, which results in a faster hydrolysis of oligosaccharides as well.
