Effects of Heat-Moisture Treatment on the Physicochemical Properties, Structural Characteristics, and Anti-Ulcerative Colitis Activity of Yam Starch

Yam starch (YS) alleviates ulcerative colitis (UC), but whether heat-moisture treatment (HMT) enhances this effect remains unclear. This study examined the impact of HMT on the structural features of yam starch and yam flour (YF) and their UC-mitigating capacity. The results showed that HMT increased the resistant starch (RS) content in YF by forming starch-lipid complexes and, in YS, it enhanced the RS content through recrystallization. Animal experiments demonstrated that YF, HMT-modified YF, YS, and HMT-modified YS all alleviate UC symptoms, with HMTYS being the most effective. Specifically, HMTYS corrected DSS-induced intestinal flora imbalances by promoting beneficial bacteria (Lachnospiraceae_NK4A136_group, bacteroides, and akkermansia). Short-chain fatty acids produced from RS fermentation by these bacteria repaired the intestinal barrier and inhibited inflammation, creating a cycle that alleviated the colitis. Fecal microbiota transplantation (FMT) experiments confirmed that HMTYS alleviates UC by modulating the gut microbiota and increasing the level of SCFA production.