Effect of addition of soybean protein isolate on the retrogradation of rice starch

Summary In this study, a hybrid system was prepared by mixing rice starch (RS) with different mass fractions (0%–10% dry weight) of soy protein isolate (SPI) to investigate its retrogradation characteristics during storage. The results showed that the addition of SPI led to an increase in pasting temperature and a decrease in setback (SB) and aging rate ( P < 0.05). When the level of SPI was increased to 10%, the pasting temperature reached a peak of 75.28°C, resulting in a decrease of 16.52% in regrowth rate and 51.61% in aging rate. The analysis of hardness and secondary structure indicated that the inclusion of SPI resulted in a less robust starch gel structure in comparison to RS, leading to a decrease in gel hardness and the short‐range ordered structure of starch. The pore structure of the starch gel was observed to be smaller and more uniform following the addition of SPI. The presence of SPI hindered the recrystallisation of starch granules, consequently leading to a delay in starch retrogradation. The results of this study have validated the positive effect of incorporating SPI on the anti‐aging properties of starch during storage. This serves as a foundational basis for enhancing the processing attributes of RS and the overall quality of starchy food products.