Study On The Synergistic Effect Of Anthocyanins And Linoleic Acid In Enhancing Wheat Starch Digestion Resistance And Its Glucoregulation Mechanism

Starch,as an important component of human diet,is the main source of energy for daily metabolic activities in the body.It is widely distributed in nature and is the main form of carbohydrates in plants,playing a role in providing thermal energy and improving the texture of food in the food system.The digestion and metabolism of starch have a significant impact on blood sugar response,and its digestion characteristics have been widely studied.Starchlipid complexes,as a new type of complex starch,not only affect the physicochemical properties of starch,but also promote the improvement of its anti-digestion ability.However,starch products are affected by interactions among various components in food,and different processing conditions significantly affect the system interaction,which has been rarely reported.Therefore,this study explored the effects of different conditions such as p H and ion concentration on the physicochemical properties,complex formation,and anti-digestion ability of the starch-lipid complex system.The formation mechanism of starch-lipid complexes is mainly that the starch molecule chains swell after water absorption,and then reassemble into a spiral cavity structure with intermediate lipophilicity and outer hydrophilicity,where lipid components enter the cavity and interact with starch to form complexes,and the hydrophilic parts in the structure are more exposed.Anthocyanins are important water-soluble natural pigments found in dark cereals that can significantly improve the anti-digestion ability of cereal starch.Therefore,this study added water-soluble component anthocyanin to the starch-lipid complex system to form a ternary complex system and increase the content of slow-digesting starch(SDS)and resistant starch(RS)in the system to enhance digestion resistance.Through X-ray diffraction(XRD)and Fourier transform infrared spectroscopy(FTIR)characterization and analysis of the interactions and ordered structure of the ternary system,the formation and interaction mechanism of the complex were clarified.Based on in vitro experiments and the establishment of a T2 DM mouse model,this study investigated the regulation of blood sugar by the complex system containing resistant starch and the improvement of T2DM-induced intestinal microbiota disorder.The main conclusions are as follows:The RVA results showed that linoleic acid is more prone to form complexes with different types of starch,and the p H range of 7-9 is favorable for the formation of starch-lipid complexes.A low concentration of sodium ions facilitates the formation of more complexes.XRD results also indicated the presence of starch-lipid complexes in the system under the forementioned conditions,while calcium ions did not have a significant effect on promoting complex formation.After the formation of complexes between starch and fatty acids,the crystal structure changed from A-type to V-type,presenting the typical crystal structure of starch-lipid complexes,and the relative crystallinity increased.The formation of complexes significantly increased the content of SDS and RS in the system,with the wheat starchlinoleic acid(WS-LA,WL)system under p H regulation(p H 7-9)showing the most significant increase in SDS and RS,with contents of 33.15% and 31.65%,respectively.Optimized composite ratio was used to prepare a wheat starch-linoleic acid-quercetin(WLA)ternary composite system by adding quercetin in a ratio of 10:1(m: m).XRD results showed that compared with wheat starch(WS),the crystal structure of wheat starch-linoleic acid(WL)and wheat starch-linoleic acid-quercetin composite systems changed from the original A-type crystal structure to the typical V-type crystal structure with an increase in the amount of composite generated,and the relative crystallinity increased to 42.6%,indicating an increase in long-range structural order.FTIR results indicated that quercetin and WL were mainly connected outside the starch molecular chain through hydrogen bonding.The comparison of specific transmission ratio values showed that the short-range molecular structure order decreased with the formation of composite.The in vitro simulated digestion results showed that the content of resistant starch(RS)in the WLA composite system was1.65 times higher than that in WS,indicating that the system has good digestion resistance.Dietary intervention significantly improved glycated hemoglobin levels,blood glucose,insulin levels,as well as glucose tolerance and insulin resistance index in T2 DM mice.In addition,physiological and biochemical indicators showed that composite intervention improved GLP-1,GIP,TC,TG,liver glycogen,C-peptide,LDL-C,HDL-C,FFA,ALT and AST levels induced by T2 DM to varying degrees.Further histopathological analysis of tissue sections showed that the composite significantly alleviated liver and pancreatic tissue damage.The composite was able to significantly upregulate protein expression levels of IR-β,pIRS1/IRS1,p-PI3K/PI3 K,p-AKT/AKT,p-GSK3β/GSK3β,and p-GYS1/GYS1,increase glycogen synthesis capacity,and thus regulate blood glucose levels.Due to differences in resistant starch content,WLA had a more significant regulatory effect than WL,and the stronger the digestion resistance,the more significant the improvement effect.Intervention with the complex,particularly WLA,helps to increase the relative abundance of beneficial gut microbiota.Functional prediction results indicate that the WLA complex treatment group can significantly increase the gene abundance of carbohydrate metabolism,cofactor and vitamin metabolism,amino acid metabolism,and polysaccharide synthesis pathways.Correlation analysis shows that Firmicutes have a significant positive correlation(P<0.05 or P<0.01)in regulating FBG,TC,TG,LDL-C,HDL-C,ALT,AST,FFA,Hb A1 c,GLP-1,C-peptide,and HOMA-IR indicators in T2 DM mice.Spirochaetes are significantly positively correlated(P<0.05)with BW,OGTT,liver glycogen,GIP,and insulin levels.In addition,Proteobacteria,Actinobacteria,and TM7 are almost positively correlated with all relevant indicators.Compared with the WS intervention group,the reason for improving the relevant indicators is mainly positively correlated with the degree of starch digestibility in the complex.This study helps to deepen the understanding of the mechanism of regulating blood sugar by complex containing resistant starch and provides ideas for further developing sugar-control food or related functional products with preventive and therapeutic effects on T2 DM,providing more theoretical references for expanding the processing channels of staple foods.