| With the development of economy and the improvement of living standard,metabolic syndrome such as diabetes and obesity have a high incidence,which seriously endangers human health.Resistant starch（RS）,which escapes enzyme digestion in the small intestine and is fermented by the microbiota in the colon,can improve insulin resistance in diabetic and obese patients by regulating the intestinal flora.Tea polyphenols can inhibit amylase activity,reduce starch digestibility,regulate intestinal flora and other health effects.Long-term consumption of tea polyphenols can help reduce the risk of diabetes and other chronic diseases.The main purpose of this paper is to study the synergistic regulation of intestinal microflora by resistant starch and tea polyphenols,and the potential improvement of diet-related chronic diseases.Firstly,amylose with different degree of polymerization was prepared by debranchation of corn starch and gradient alcohol precipitation,which was combined with lauric acid and epigallocatechin gallate（EGCG）to prepare starch-lipid complex and starch-lipid-EGCG complex system,and its structure and in vitro fermentation characteristics were studied.The results are as follows:Corn starch was completely debranched with Pullulanase for 24 h,and then the starch was precipitated step by step with three kinds of ethanol with different gradient,and three kinds of amylose with different degree of polymerization were obtained.By characterizing the structure of the complex,we obtained amylose（1:2 DMS）was obtained under the gradient of 1:2 alcohol precipitation,and its polymerization degree（DP）ranged from 383to 2950.The prepared complex has the best thermal stability,maximum enthalpy value and composite index,the strongest XRD diffraction peak and the smallest half peak width,indicating that the complex has the most stable structure,the most ordered and the most content ofⅡb type complex.However,1:1 DMS（DP:37-75）was more likely to formⅠatype complex with unstable structure,while 2:1 DMS（DP:8-32）could not form complex.After the addition of EGCG,the enthalpy and composite index of the ternary system decreased,the relative crystallinity decreased,and the half peak width of 480 cm-1increased,which indicated that EGCG did not enter the amylose spiral cavity and hindered the starch and cinnamic acid recombination.According to the above results,theⅡb type complex with stable structure was selected for in vitro fermentation experiment.The results showed that the binary and ternary systems prepared by DMS and 1:2 DMS could be fermented slowly,which satisfied the energy requirements of the distal colon.Among them,1:2 DMS-LA-EGCG could produce the most butyric acid.Through the analysis of bacterial community,we know that the compound group significantly reduced the relative abundance of pathogenic bacteria.We found that different sample groups had different bacterial community changes.1:2 DMS-LA and 1:2DMS-LA-EGCG produced more beneficial bacteria than other complex groups,for example:Phascolarctobacterium,Roseburia,Megamonas,Ruminococcus and Lactobacillus.Most of these microflorae showed significant positive correlation with the content of short-chain fatty acids.In the ternary system with high EGCG content,the relative abundance of beneficial bacteria was higher than that in the binary system.Therefore,the structure of the complex is an important factor affecting the change of gut microbiota,and EGCG and starch-lipid complexes can jointly regulate the composition of gut microbiota... |
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