Effect of whey protein isolate on the quality of rice bread

Abstract

This study systematically investigated the improvement of rice bread quality with increasing percentage of whey protein isolate (WPI) from 5 % to 25 %, integrating raw material properties (gelatinization and thermal characteristics), processing performance (rheology and microstructure), and product quality (texture, specific volume, and flavor) in a multilevel comprehensive analysis. With increasing WPI content, the gelatinization temperature of the WPI–rice flour system increased by 3.24 %, partially inhibiting starch gelatinization and enhancing internal hydrogen bonding. WPI filled the interstitial spaces between starch granules, stabilized the dough structure, and facilitated the formation of more numerous and uniformly distributed pores, with the total pore number increasing by 28.9 % compared with CK. During baking, WPI promoted water absorption and retention, generated more steam, increased specific volume by 17.6 %, and enhanced protein–starch crosslinking to form a more stable network structure. At 15 % WPI, the physicochemical properties of rice bread were significantly improved. Hardness was reduced by 54.3 %; springiness increased by 6.5 %; and a distinctive milky flavor was observed. The optimization of WPI in rice bread provides both nutritional and quality advantages, providing a valuable reference for the improvement of rice–based baked products.