Properties of Starch and Protein Isolated from Certain Mungbean Lines

Abstract

Twenty mungbean lines were analysed for chemical compositions. The results showed that they contanined 7 to 9% moisture, 19 to 24% protein and 59 to 65% carbohydrates. Starch and protein were isolated from three mungbean lines, VC 2742, VC 2745, VC 2755 and the cultivar U – thong 1, using 0.1N.Na2 Co3 solution. The amount of isolated startches were 12 to 22%, having the purity of 82 to 89% while the amount of isolated proteins were 12 to 17%, having the purity of 70 to 77%. Using scanning electron microscope to examine the mungbean flour and starch granules, the results showed that the flour had many components attached to starch granules while the isolated starch showed rather clear starch granule, circle, oblong or kidney-like shapes with the size of 14 to 19 microns in width and 21 to 29 microns in length. The functional properties of isolated starch and protein were determined. The results showed that starch isolated from the three mungbean lines had 84 to 93% water absorption, 72 to 80% oil absorption and minimum gelation at 16 to 20% starch by volume which were not quite difference from that of U-Thong 1,. The isolated protein had much lower amount of water absorption, oil absorption and minimum gelation than isolated starch from the same source and some-what difference from U-Thong 1. Protein isolated from U-Thong 1 had less water and oil absorption, but required almost twice protein to form gel, compared to the protein isolated from the three mungbean lines.