Caracterização e efeitos do armazenamento de amêndoas com películas e despeliculadas sobre propriedades das frações proteica e lipídica de Castanha-do-Brasil

Abstract

Brazil nut (Bertholletia excelsa Bonpl.) broken type with skins and dehulled were analysed. Obtained defatted flour (BNDF), protein isolate (BNPI), albumin, globulin, prolamin and glutelin protein fractions and non solubilized material that were evaluated as characteristics physicochemical, biochemical, amino acids, electrophoresis SDS-PAGE, thermal behaviour. The extracted oil from hydraulic cold pressing were evaluated as characteristics physicochemicals, fatty acids profile, themogravimetric behaviour. Nuts and defatted flour were evalueted by optical microscopy and electron microscopy. Albumin (41.34%), glutelin (36.35%) fractions presented highest concentration, followed for globulin (19.02%) and the prolamin fractions, that presents lowest values than 0.5%. The electrophoretics profiles of BNDF, BNPI, albumin, globulin, prolamin, glutelin frations and non solubilised material indicated your complexity. The Brazil nut matrix is rich in proteins, wich have molecular weigth between 9.32kDa and 52.04kDa. The essentials amino acids from protein isolate and fractions maintains characteristcs of the defatted flour matrix. DSC analysis shows that proteins denaturation of defatted flour is higest than protein isolate, lowest than in the albumin and globulin fractions and higest in the prolamin and glutelin fraction and non solubilized material, wich shows enthalpies (∆H) of 0.67J.g-1 ; 12.89 J.g-1 ; 7.75 J.g-1 ;0.26 and 0.94 J.g-1 , respectively. Phenolic compounds were different in the time and in tratments, being that Brazil nut broken type wich skil presented values of 136.07mgAG100g-1 at the beginning of storage time and 123.62mgAG100g-1 in final time storage at twelve months. Hydraulic cold pressing allowed obtain oil wich characteristics (acidity, peroxides and saponification) according to brazillian legislation to others edible oils. The fatty acids profile shows that removal brown skin promoted qualitatives changes in the oil that presented significatives diferences when compared to dehulled Brazil nut broken type oil. The thermogravimetric behaviour (TG/DTG) of the oil analysed presents one only evento mass loss, that occours from peak temperature at 409.41ºC wich mass loss of 99.59%, in the case of the brazil nut wich skin and 420.00ºC and mass loss of 100% to dehulled Brazil nut, in the beginning of storage time. This behaviour was atributed to presence of higher amounts of poliunsatured fatty acids in the zero time to nuts witch skin, which are very sensitive to oxidation process and, when presents reduce the stability as a whole. In the case of dehulled nuts at the beginning of storage has been observed to reduce these acids. Optical and electron microscopies analyses reaveled that brown skin that involves the almonds of Brazil nuts seems to possess some secondary compounds (for example, phenolic compounds) that mantain the cellular structure organized. In the Brazil nut large type with skin, strutures whith cellar wall and oleossomes apears much preserved than observed in the Brazil nut broken type wich skins. In the Brazil nut dehulled this structures not seem to exist or are much more disorganized. The maintenance of the brown skin that involves Brazil nut amond, notably the broken type used in this research can contribute to better organization of the cell contents, providing greater protection of physical and chemical characteristics and stability of the oil.