Structural alterations in butyrylated and recrystallized high-amylose maize starch and their effect on gut microbiota during in vitro fermentation

In this study, type-3 resistant starch (RS) with enhanced thermal stability and excellent short-chain fatty acid (SCFA) production was obtained through the butyrylation and subsequent recrystallization at 4 degrees C of highamylose maize starch (HAMS). We comprehensively examined and contrasted the structural attributes and in vitro human fecal fermentation behavior of butyrylated RS (BRS) with varying degrees of substitution. Fouriertransform infrared analysis validated the successful integration of carbonyl groups into the starch matrix. This phenomenon was evident through the characteristic peaks at 1727 cm-1. X-ray diffraction and thermal stability analyses delineated the distinct B-type crystalline structure and high relative crystallinity of 25.31 % and 22.23% of the 10 % and 15% butyric anhydride BRS-10 and BRS-15, respectively, which differed from that of HAMS. Their second peak gelatinization temperature values reached 95.6 degrees C and 92.6 degrees C. The in vitro fermentation of BRS fostered SCFA production, boosting the relative abundance of beneficial bacteria (e.g., Ligilactobacillus and Roseburia). Meanwhile, the extensively modified BRS favored the propagation of Faecalibacterium and Bifidobacterium, maintaining intestinal microbiota advantage. These findings underscore the significant effects of butyrylation modification on fermentation kinetics, metabolite profiles, and gut microbiota composition, providing invaluable insights into the development of functional food products that aim to bolster colonic health.