The effect of heat treatments on in vitro starch digestibility and resistant starch of selected cereals

The effect of heat treatments on in vitro starch digestibility of rice, barley, and foxtail millet with different levels of amylose were studied. The effect of heat processes on the amount of resistant starch (RS) content was also analyzed. Cereal samples were tested either raw, boiled, or steamed/roasted. Amylose content varied from 30.2-39.0% in normal cereals to 5.2-6.7% in low amylose cereals. Cereal samples showed different resistances to starch hydrolysis. Raw rice samples showed relatively high starch hydrolysis, while raw barley samples demonstrated the lowest susceptibility to alpha-amylolysis. Heat treatments significantly increased the starch digestibility in rice, barley, and foxtail millet samples with low amylose content. RS contents of cereals were in the range of 0.05-0.48% (raw), 0.23-3.66% (boiled), and 0.22-3.15% (steamed/roasted). RS contents after heat treatments were positively correlated with amylose content in the cereal samples.