(The) study on the extraction of protein and the production of edible fibers from defatted rice bran

Abstract

Defatted rice bran which is low-priced is currently used as a low grade feed. In this study, an attempt was made to utilize the defatted rice bran as an edible protein source. Defatted rice bran protein concentrate was obtained by alkaline extraction and the concentrate in the combination of carboxylemthyl cellulose was spun into an edible fiber to check the possibility of using the fiber as a mear analogue. Alkaline extraction of defatted rice bran removed 33.5 to 80.0\% of total crude protein as PH increased from 7 to 12 when the bran was stirred for 1 hour at 25$^\circ$C and 1,000rpm with 9 volumes of extractant (optimal conditions). Grinding the bran had little effect, though solubilization of protein increased somewhat at PH 11. The extracted protein was separated by isoelectric precipitation (PH 4.5). Drying of the precipitated protein yielded 60.0\% of the bran protein, the purity of which was 80.5\%. Amino acid analysis showed that the rice bran protein concentrate (RBPC) had good amounts of essential amino acids, with exception of lysine. The rheological behavior of its dough solution was evaluated using the Brookfield synchro-lectic RVF Viscometer. Viscosity varied in proportion to the amount of RBPC, sodium hydroxide, and 0.6\% sodium hydroxide had good rheological behavior for spinning. This dough solution showed some rheopectic and pseudoplastic characteristics. After 30-40 minutes, the time dependance was reduced and its dough solution could be thought as a pseudoplastic material. This dough solution had good apparent viscosity for spinning (60-300 poise) above $1.5\times10^{-2}\;\sec^{-1}$ in shear rate. The edible fibre was produced by a wet spinning technique using an especially designed apparatus. Composition of the coagulating solution was an acetic acid solution with 20\% (W/V) sodium chloride. The pressure of pumping was 100psig and the speed of the roller was 10 rpm. The produced fiber had good texture parameters; brittleness, hardness, el...