Fabrication of oxidized starch/whey protein isolate complexes for fluidized powder coating of starch: A novel preparation strategy of resistant starch granules.

Exploring methods to retard starch digestion is essential for achieving related health benefits, including metabolic regulation. In this study, we proposed a novel strategy to reduce starch digestibility via fluidized bed coating. Initially, coating materials were developed based on the electrostatic complexation between oxidized starch (OS) and whey protein isolate (WPI), with epigallocatechin gallate (EGCG) employed to strengthen intermolecular interactions. This combination synergistically decreased apparent viscosity and improved film-forming properties. Furthermore, it influenced the multi-scale structural assembly during film formation, thereby enhancing mechanical properties and digestion resistance. The engineered OS/WPI complexes were subsequently applied to coat native starch granules via fluidized bed coating. The resulting coating layers functioned as physical barriers that restricted starch gelatinization and digestion, leading to a significant increase in resistant starch (RS) from 8.68% to 34.42%-44.10%, alongside a significant decrease in predicted glycemic index (pGI) from 92.07 to 56.93-61.30, corresponding to medium-GI foods (55-70). Moreover, the coated starch granules remained as discrete state without noticeable agglomeration, indicating substantial potential for application in food systems. Overall, these findings provide a novel strategy for preparing resistant starch granules, which holds considerable promise for developing starchy foods with reduced digestibility and for mitigating of diet-related chronic diseases.