Extraction of two albumin fractions from amaranth grains: Comparison of some physicochemical properties and the putative localization in the grains

Two alfiumin fractions were extracted from defatted flours of seeds of Amaranthus hypochondriacus and A. cruentus. One fraction (Alb-1) was extracted with 0.5m NaCl or water when used as the first solvent. Another fraction (Alb-2) was extracted with water after removing Alb-1 and globulin. Apparent pIs of Alb-1 and Alb-2 were 4.5-7.5 and 5-6, respectively. Alb-2 was precipitated by various metal ions (1 mm), while Alb-1 was not. Alb-2 contained four major components (M r = 56, 36, 26, 22 kD), although Alb-1 had no particular major proteins. Pronase treatment of amaranth flour before protein extraction decomposed Alb-1, but not Alb-2, as seen by SDS-PAGE analysis. The findings that Alb-2 was protected from the Pronase treatment and it could not be extracted until Alb-1 and globulin were removed suggests that Alb-2 might be associated with protein bodies [Irving et al., J. Food Sci., 46, 1170 (1981)].