Effect of pepsin and SO2 treatments on yield and properties of starch from Tabat and Wad-baco sorghum cultivars.

Abstract

This study aims to evaluate the effect of pepsin and SO2 treatments on the yield and physicochemical-, functional-, and color properties of starches isolated from Tabat and Wad-baco sorghum cultivars. Results revealed that starch yield from treatments B (steeping for 7h; 3h in distilled water, 4h in 0.1M sodium acetate buffer, pH 4.5), BE (steeping for 7h; 3h in distilled water, 4h in 0.1M sodium acetate buffer, pH (4-4.5) with 250mg pepsin), BES (steeping for 7h; 3h in distilled water, 4h in 0.1M sodium acetate buffer, pH 4.5 with 250mg pepsin and 0.2% SO2), and S (steeping for 7h; 3h in distilled water, 4h in 0.2% SO2) were significantly higher than that from the control (A; steeping for 24h in 0.2% SO2) in both cultivars. The combination of pepsin and SO2 treatment (BES) produced an increased starch yield of 78.90% and 85.56% from Tabat and Wad-baco, respectively. Micrographs showed hydrolysis of the protein matrix attached to the starch by pepsin, which created holes on the surface of starch granule. Gelatinization temperature decreased in the treated starches from both cultivars compared to control. Water- and fat- absorption capacities were higher in the starch from all treatments compared to control. Generally, enzyme treatment improved the yield and functional properties of starches from both cultivars.