ABSTRACT
Microwave treatment is a sufficiently alternative technique to be applied widely in food production and cereals protection against insect pests. Water-soluble proteins were washed out from microwave-heated wheat grain for the purpose of assaying the influence on biological activities, reducing sugars content, and SDS-PAGE electrophoresis proteins patterns. The differences between microwave-heated grain samples were verified by analysis of variance at the P ≤ 0.05 level of significance. Microwave heating of wheat grain within the temperature range of 28–98°C caused a decrease in water-extractable proteins, statistically significant when grain temperature reached 79 and 98°C. Statistically significant increase in reducing sugars content was noted in grain samples heated only to 48°C; a decrease was noted above this temperature. All biological activities studied (amylolytic and inhibition activities against α-amylases from insects (Sithophilus granarius L., Tribolium confusum Duv., Ephestia kuehniella Zell.), human saliva, hog pancreas, antitryptic activity) were distinctly diminished in grain samples heated to 79°C. At the highest grain temperature of 98°C, the loss of all biological activities were even more pronounced due to denaturation of ≈45% of extractable proteins. Among the wheat albumins studied by SDS-PAGE, only eight and nine protein bands were detected in the grains heated to 98 and 28°C, respectively, whereas 12 bands were present in the control. The highest number of protein bands (13) was found in the grains heated to 48 and 64°C, respectively.
