Inhibition from whey protein hydrolysate on the retrogradation of gelatinized rice starch

The retrogradation of gelatinized starch is primarily responsible for the decreased qualities and shelf-lives of starch-based foods. Inspired by the mixture of rice flour and infant milk powder in daily life and the inhibition on retrogradation of gelatinized starch by protein hydrolysate, the purpose of this study was to provide scientific insights into whey protein hydrolysate (WPH) as a potential anti-retrogradation additive for gelatinized rice starch (RS). The addition of WPH restricted the amylose leaching and swelling of RS, resulting in decreased peak viscosity and peak storage modulus, and the setback values reduced as well. The combinations between WPH and starch polymer chains reduced the action site of the enzyme, increasing the resistant starch content. On retrogradation (storage at 4 °C for 14 days), compared with RS, the hardness and water mobility significantly decreased with the addition of WPH; the relative crystallinity decreased from 13.82 to 10.44%, while the 1047 cm−1/1022 cm−1 ratios reduced from 0.925 to 0.822, which may be attributed to the fact that WPH prevented the molecular associations and formation of hydrogen bonds among the starch polymer chains. The retrogradation kinetics was determined using the Avrami model and indicated that WPH could effectively inhibit the recrystallization of RS. These results above demonstrated WPH could be a potential anti-retrogradation additive for prolonging the shelf-life of rice-based foods.