Study On The Electrophilic Binding Mechanism Of Sugar And Their Degradation Product Furfural To Blueberry Anthocyanins

Anthocyanin is an important natural water-soluble pigment in blueberries and other berries.Its natural high antioxidant activity endows blueberries and other foods rich in anthocyanins with a variety of physiological functions.Therefore,the market prospect of its deep-processed products is very broad.In food industry,it is inevitable to add sugar to increase the flavor of food,but sugar has a significant effect on the stability of anthocyanins.The ability of sugars to affect the stability of anthocyanins is closely related to their degradation products,furfural compounds,but the mechanism of action is still unclear.Therefore,this study took the effect of sugars on the stability of anthocyanins as the breakthrough point,and systematically studied the effects of sucrose,fructose,glucose and maltose on the stability of anthocyanins under different concentrations,heating and storage conditions;further use of sugars degradation product furfural(Ff)and the most common anthocyanin monomer,cyanidin-3-O-glucoside(C3G),revealed the mechanism of sugar degradation products affecting the stability of anthocyanins,and the toxicity,antioxidant activity and stability of C3G and Ff reaction products were studied.The main findings are as follows:Different concentrations of sucrose,fructose,glucose and maltose have different effects on the stability of anthocyanins during heating and storage.When heated at 85°C for 15 min,only 15%of fructose promoted the degradation of anthocyanins in the late stage of dark storage,while in light storage,all concentrations of sugars showed significant protective effects on blueberry anthocyanins.After heating at 85°C for 2 h,only15%fructose had a significant destruction effect on anthocyanins during storage in the dark;but under light storage conditions,with the prolongation of storage time,all concentrations of sucrose,5%and 15%fructose,10%glucose,and 10%and 15%maltose significantly promoted the degradation of anthocyanins,while other concentrations of sugars could significantly protect anthocyanins.Three kinds of reaction products of C3G and Ff were identified by UPLC-MS.Two of them were isomers,which were adducts of C3G and Ff.The reaction mechanism might be that the A ring of C3G in hemiketal form was added with Ff in Michael type.In addition,after the reaction of C3G and Ff,the color of the solution changed from red to dark purplish red,and the color of the reaction products were also significantly different from that of C3G.MTT assay showed that C3G and C3G-Ff I and C3G-Ff II had almost no cytotoxicity below 1 mg/m L.Compared with C3G,C3G-Ff I and C3G-Ff II had worse ABTS~+radical scavenging ability and PSC antioxidant ability than C3G.They were also less stable than C3G under the conditions of light,85°C heating and supplemented with 0.1%VC,and coexistence with C3G would further promote the degradation of C3G.C3G-Ff I was detected in the C3G solution supplemented with sucrose,fructose,glucose and maltose respectively,and the content of C3G-Ff I was higher in the samples stored under light condition.3.53 mg/m L C3G-Ff I was detected in Aronia drink stored for 6 months.