Effect of Ultrasonic Treatment on the Digestion Characteristics of Glutinous Rice Flour and Optimization of Process to Reduce Glutinous Rice Flour Glycemic Index

Objective: To study the effect of ultrasonic treatment on the digestion characteristics and glycemic index (GI) of glutinous rice flour. Methods: With GI value as the index, the effects of four factors, including emulsion concentration, ultrasonic power, ultrasonic time and drying temperature, on the digestibility of glutinous rice flour were studied by single factor test and response surface method. The results showed that ultrasound could transform the components between starches, increase the content of resistant starch, and significantly (P<0.05) reduce the GI value of glutinous rice flour. The GI value of glutinous rice flour decreased to 76.31 (14.22% lower than that of ordinary glutinous rice flour) with 30% emulsion concentration, 400 W ultrasonic power, 4 min ultrasonic time and 49℃, which was similar to the predicted value of the response surface regression equation (76.28), indicating that the regression model could be used to optimize the ultrasonic treatment process of glutinous rice flour. The crystal form of glutinous rice flour was not changed by ultrasonic treatment. Conclusion: This method could improve the digestibility of glutinous rice flour and provide experimental ideas for the further development of low GI glutinous rice flour.