Calcium Alginate Encapsulation of Rice Starch, Instead of a Physical Mixture of Both, Regulates the Fermentation Rate and Production of Acetate

ABSTRACT Calcium alginate–encapsulated rice starch (AES) could be potentially applied as a rice analog with a significantly improved amount of resistant starch, while its effects on gut microbiota remain less clear. To this end, structural characteristics of AES and their impact on gut microbiota, fermentation rate, and short‐chain fatty acid (SCFA) production were examined using an in vitro batch fermentation method. Cooked AES showed a significantly higher amount of intermolecular interactions (∼46 times), short‐range double helices, and degree of crystallinity compared to the simple mixture of rice starch and calcium alginate (Mix), resulting in a more homogenous and densely packed network microstructure. As a result, AES, instead of Mix, showed a significantly slower gas production rate (∼17%), while relatively higher production of SCFAs, especially the ratio of acetate. Bifidobacterium pesudocatenulatum was possibly responsible for the higher production of acetate in AES. Collectively, these results show that AES has the potential to be used as a slowly fermentable carbohydrate, favoring the production of acetate in the human colon.