Isolation and Physico-chemical Characterization of Mung Bean Starches

Abstract

The starch yields from both whole (MSI1) and decorticated mung bean seeds (MSI2) were 26.00 and 30.50% on total seed basis and 64.40 and 75.55% of total starch. Chemical analysis of the starch isolates i.e. MSI1 and MSI2 showed that they contained 9.00 and 8.90% moisture, 0.76 and 0.80% protein, 0.05 and 0.09% oil and 0.20 and 0.13% ash , respectively. The results also indicated that the purity of starch isolates was high. Microscopic examination (400X) showed that most mung bean starch granules had irregular shapes, which varied from oval, round to bean-shaped. Mung bean starch granule size varied from 7.65-33.15 µm with mean value at 20.40 µm. Studying the physico-chemical properties of mung bean starch indicated that the gelatinization temperature range was 65-69-75°C at initial, midpoint and final gelatinization of starch granules. Mung bean starch had a considerably lower degree of syneresis than other legume starches. Moreover, gel consistency decreased as starch concentration was increased. Viscosity of mung bean starch was high indicating that it had higher resistance to swelling and rupture than did cereal starches. The results indicated that the swelling power and solubility of the starch increased with increasing temperature. In addition, the solubility percentage increased, but non-linearly, with increasing swelling power.