In vitro digestion and fecal fermentation of encapsulated starch constructed via layer-by-layer coating of calcium alginate

This research prepared functional-resistant starch capsules by constructing multiple calcium alginate shells around calcium alginate/starch beads. Scanning electron microscopy revealed a dense structure for each layer of the calcium alginate shell, tightly encapsulating the calcium alginate/starch beads. The rapidly digestive starch content of three-layer calcium alginate shelled starch capsules decreased to 0.50 ± 1.14%, while the resistant starch content increased to 78.25 ± 1.55%. The estimated glycemic index (eGI) experiment suggested that the two-layer shell capsules (eGI: 59.91) and Three-layer shell capsules (eGI: 47.75) were classified as low-glycemic index foods . Furthermore, calcium alginate/corn starch multilayer capsules showed reduced microbial gas production and increased concentrations of propionic acid , isobutyric acid, and valeric acid compared to lactulose in vitro fecal fermentation experiment. Moreover, three-layer capsules and beads promoted a relative abundance of Bacteroidetes but inhibited the reproduction of Proteobacteria and Actinobacteria compared with lactulose and corn starch. These results suggest that constructing multi-layered sodium alginate shells for starch beads can effectively increase the digestive resistance of starch within the capsules and control its fermentation in the colon. This study will have a profound impact on the development of RS1-type resistant starch and be beneficial in the design and production of functional foods for prevention and assistance in the treatment of chronic diseases such as diabetes and obesity.