Constructed Resistant Starch Granules by Fluidized Bed Coating: In Vitro Digestion, Fermentation, and Application Assessment in Baked Foods

Abstract

The encapsulation of starch represents a promising strategy for preparing resistant starch (RS), which has been shown to mitigate the risk of diet-related chronic diseases. However, existing starch encapsulation techniques are limited by factors such as millimeter-scale dimension and low processing adaptability. Hence, this study aimed to innovatively produce micrometer-scale RS granules using a fluidized bed coating technique and to evaluate their application in the production of typical baked cakes. Result demonstrated that native starch granules were successfully coated with the well-designed coating materials (oxidized starch/whey protein isolate/epigallocatechin gallate complexes). The coated starch granules retained a powder form and micrometer-scale dimensions without alteration of starch crystalline structure. Due to physical barriers, these granules exhibited relatively low digestibility, which depended on coating duration, with RS content ranging from 45.01 to 50.18%. The coated starch granules also contributed to a stronger regulatory effect on microbial community, promoting the production of acetate and butyrate, and the growth of beneficial bacteria including Bifidobacterium and Blautia. Additionally, incorporating coated starch granules into baked cakes significantly reduced starch digestibility to 33.63–44.41% and lowered predicted glycemic index (GI) to 52.38–56.28. Although the inclusion of coated starch granules affected the quality characteristics of cake batters, the finished cakes at a suitable proportion maintained desirable texture, flavor, taste attributes, and sensory scores comparable to those of the commercial cakes. Overall, these findings underscore the potential of fluidized bed coating technique for starch granule encapsulation and RS preparation, providing foundational data for the development of nutritious, health-promoting, and flavorful starchy foods.