Physico-chemical and structural properties of four rice bran protein fractions based on the multiple solvent extraction method

Abstract

Wang Ch., Xu F., Li D., Zhang M. (2015): Physico-chemical and structural properties of four rice bran protein fractions based on the multiple solvent extraction method. Czech J. Food Sci., 33: 283–291. The physicochemical and structural properties of the concentrated rice bran protein (CRBP) and rice bran protein fractions – RBPF (globulin , prolamin, and glutelin) were investigated on the basis of multiple solvent extrac tion method. T he protein fractions mainly consisted of essential amino acids except for prolamin . The a mino acid composition of concentrated protein was superior to soybean protein isolation, such as valine, methionine, leucine, phenylalanine, and histidine, with similar characteristics of solubility, emulsification, and foaming . Based on the dif ference in amino acid composition, a ll these five proteins showed relatively high surface hydrophobicity more than 369.3 of prolamin . CRBP and RBPF were composed of different molecular subunits in SDS-PAGE profile. The circular dichroism spectra (CDS) in synergy showed that the primary structures of RBPF were β- protein folding and random coils with various denaturation temperatures in the range of 78.69°C for glutelin and 92.88°C for globulin . The fluorescence spectrometry assays showed that the blue shift occurred at 348 nm for globulin , while the red shift occurred for the concentrated protein, albumin, and globulin at 356.2, 348.6, and 347.0 nm, respectively . Therefore, the research presents the basic characterisation for further application of natural rice bran protein in the food industry.