Behavior of retrogradation retardation in rice starch paste by raw wheat flour addition

Abstract

The effect of raw wheat flour on starch retrogradation retardation was investigated in a rice starch paste model. Specifically, in terms of amylase activity present in the wheat flour, the retardation effect was investigated depending on reaction temperature (40, 60, and 80oC), incubation time (0, 20, 40, and 60 min), and wheat flour addition levels (0-10%). An increase in wheat flour concentration resulted in a rapid decrease in the elastic modulus (G') as the incubation time increased. The G' changes of the rice starch pastes were furthermore fitted by the first order reaction for the reaction rate estimation on the temperature basis. The experimental reaction rate of the paste sample incubated with 10% wheat flour at 40oC exhibited good agreement with the predicted value. This result implied that the first order reaction kinetics could be suitable to predict the changes in the G' as a function of incubation temperature and wheat flour concentration.