RESUMEN
Extraction, fractionation and characterization by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis of proteins from Carioca 80 beans (Phaseolus vulgaris) were performed at three pH values (2.5, 8.0 and 9.0). Extraction at pH 7.0 proved to be more efficient and, after dialysis, produced a better separation of the albumin and globulin fractions. Relative mobility of the main protein in the globulin fractions occurred between 0.30 and 0.40, and dissociation was observed when the pH was increased. The two most representative bands gave molecular weights of 35,400 and 76,900, while in regard to the trypsin inhibitor, three bands gave 28,800, 22,500 and 18,300. Pepsin and pancreatin in vitro digestibility rendered values of 33.43% and 62.63% for whole flour and for protein precipitated at pH 4.5, respectively. The content of available methionine found, of 1.36 g/16 g N, appears to be high in relation to that of other bean varieties.
Asunto(s)
Fabaceae , Harina , Proteínas de Vegetales Comestibles/aislamiento & purificación , Plantas Medicinales , Electroforesis en Gel de Poliacrilamida , Concentración de Iones de Hidrógeno , Metionina/análisis , Valor Nutritivo , Proteínas de Vegetales Comestibles/análisis , Inhibidores de Tripsina/metabolismoRESUMEN
One of the problems in the handling and processing of various kinds of fruits, is the enzymatic and nonenzymatic browning. The polyphenoloxidases are strictly related with the first aspect, needing therefore, more attention from the scientists and food industries. These enzymes oxidize mono, di and polyphenols in the presence of molecular oxygen, producing dopachromes which are polymerized to melanins as a final product. Their mechanism of action, however, is still unknown. The purpose of this article is to provide specific information as to the nature and behavior of the polyphenoloxidases found in different kinds of fruits and foods.
Asunto(s)
Catecol Oxidasa/metabolismo , Frutas , Melaninas/biosíntesis , Monofenol Monooxigenasa/metabolismo , Fenoles/metabolismo , Ácido Ascórbico/farmacología , Fenómenos Químicos , Química , Manipulación de Alimentos , Oxidación-Reducción , Fenoles/aislamiento & purificaciónRESUMEN
Um dos problemas encontrados na manipulacao e processamento de varias frutas e o escurecimento enzimatico e nao enzimatico.As polifenoloxidases estao estreitamente ligadas a este primeiro aspecto merecendo, portanto, a devida atencao por parte dos pesquisadores e industrias de alimentos.Essas enzimas, oxidando mono, di e polifenois na presenca de oxigenio molecular, produzem dopacromos que sao polimerizados e originam melaninas como produto final.Entretanto, o seu mecanismo de acao e ainda obscuro. O presente artigo tem o objetivo de fornecer informacoes especificas quanto a natureza e comportamento das polifenoloxidases encontradas em diferentes frutas e alimentos