Soybean protein isolate inhibiting the retrogradation of fresh rice noodles: Combined experimental analysis and molecular dynamics simulation

Retrogradation of fresh rice noodles (FRNs) is detrimental to the customers’ acceptance of these rice products. In this study, combined experimental analysis and molecular dynamics simulation were used to explore the mechanism underlying soybean protein isolate (SPI, 0–12%) inhibiting the retrogradation of FRNs. The FRNs showed fast retrogradation and hardening at the 1st day, whereas the aging rate was slowed down in the presence of SPI during the 5-day storage. This was due to that SPI increased the water-holding capacity and buffered the acidity of the system. Differential scanning calorimetry showed that SPI prevented the formation of ordered starch structures during retrogradation. From the results of molecular dynamics simulation, it was found that 7 S of SPI could reduce the deformation degree of starch to a lower extent than 11 S in the gelatinization process at 95 °C. However, 11 S elicited stronger non-covalent interactions with starch than 7 S during retrogradation at 4 °C, thus stabilizing starch structures and inhibiting retrogradation of FRNs. Our study illustrated a facile approach to inhibit the retrogradation of FRNs, which would properly broaden the application scenarios of traditional products with enhanced shelf life and taste attributes.