In Vitro Fecal Fermentation Of High-amylose Maize Starch-lipid Complex And Its Regulation Mechanism On Gut Microbiota

Starch-lipid complex,as a kind of resistant starch(RS),is of great significance to human health.They can reduce intestinal p H,increase the production of short-chain fatty acids(SCFAs),promote the growth of beneficial bacteria.In recent years,there have been a large number of reports on the positive effects of RS on gut microbiota and metabolism regulation in vivo and in vitro fecal fermentation.However,there are still few studies on RS5,which are limited to the comparison of fermentation characteristics of RS2,RS3 and RS5,but the comparison of fermentation characteristics among different RS5 is temporarily lack.In this study,high-amylose maize starch(HAMS)and different types of fatty acids were used as raw materials to obtain the starch-lipid complex(RS5)formed by starch and various kinds of fatty acids with different chain lengths and saturation.After in vitro fermentation,we found that RS5 have a slow fermentation rate,release more propionate and butyrate and promoted the relative abundance of the Roseburia,Bacteroides and Prevotella.We also found the fermentation characteristics of RS5 is mainly associated with the structure of starch but not the carbon chain length or saturation of fatty acid.The results of this experiment can improve the theoretical basis for the development of personalized diet and healthy food.Starch-saturated fatty acid complex was obtained by heat treatment using high-amylose maize starch and long chain saturated fatty acids commonly found in diet,such as lauric acid,palmitic acid,myristic acid and stearic acid as raw materials.The chemical properties of starchsaturated fatty acid complex were compared with high-amylose maize starch and debranched starch.It was found that starch-saturated fatty acid complex formed V-type crystalline structure,and with the increase of fatty acid chain length,the degree of complex and the amount of Vtype crystallization gradually decreased.It was found that the gas production rate of fructooligosaccharides was 1.57 m L/h in the first 8 hours of fermentation,while the gas production rate of starch-saturated fatty acid complex was about 1.13 m L/h,showing a relatively slow fermentation rate.After fermentation for 24 h,the starch-saturated fatty acid complex produced 20?25 m M acetate and 30?35 m M butyrate,indicating that the starchsaturated fatty acid complex had the effect of promoting the yield of acetic acid and butyrate.By 16 S r RNA analysis of the gut microbiota of fermentation,it was found that the starchsaturated fatty acid complex could promote the relative abundance of Roseburia and Bacteroides,in which the relative abundance of Roseburia might be related to the high butyric acid yield.In general,starch-saturated fatty acid complex can reduce the adverse effects of pure saturated fatty acid on gut microbiota,improve the relative abundance of beneficial bacteria and promote the balance of gut microbiota,but the fermentation characteristics of several starch-saturated fatty acid complex have little difference,and acid production content has no significant difference.This indicates that the carbon chain length of the complex fatty acid has little influence on the fermentation characteristics of RS5,but there are certain differences in the relative abundance of various bacterial communities.High-amylose maize starch and several fatty acids with different saturation,namely stearic acid,oleic acid,linoleic acid and linolenic acid,were used as raw materials to obtain starchunsaturated fatty acid complex.The physical and chemical properties were determined and in vitro fecal fermentation experiments were carried out.The gas production rate,SCFAS production and microbial community structure were determined.It was found that the gas production rate of starch-unsaturated fatty acid complex was always slow during fermentation time,but the gas production tended to be the same at the end of fermentation,indicating that after in vitro intestinal fermentation for 24 h,gut microbiota made full use of the starch samples and produced abundant SCFAs,especially the propionate content reached 21?24 m M after fermentation for 24 h.At the same time,16 S r RNA analysis of the gut microbiota affected by fermentation showed that the starch-unsaturated fatty acid complex significantly promoted the relative abundance of Prevotella,which may be related to the higher propionate yield of starchunsaturated fatty acid.In terms of fermentation characteristics,there was no significant difference among starch-unsaturated fatty acids,indicating that the fecal fermentation characteristics of RS5 were less affected by the degree of unsaturated fatty acids,which was mainly related to the structural characteristics of RS5 itself.