Study On The Molecular Modification,activity And Prebiotic Activity Of Anthocyanins From Black Rice And Preparation Of Anthocyanins Salts

In this study,the modification of cyanidin-3-glucoside(C3G),changes of stability and prebiotics activity of C3 G after modification,and process conditions of anthocyanins salts were studied.Firstly,C3 G was modified by enzymatic modification,reaction conditions of enzymatic modification were optimized,and reaction products were detected and purified by LC-MS and preparative HPLC,respectively.Then,the stability,antioxidant in vitro,prebiotics activity and metabolites of C3 G were investigated.Finally,the anthocyanins salts,which had antioxidant activity,were developed by spray drying technology,and physical properties of anthocyanins salts were further studied.The main results are as follows:1.The molecular modification of C3 G was studied.The selection of reaction media and acyl donor was conducted by studying the effect of different solvents and acyl donors on the conversion of C3 G,and tert-butanol and p-coumaric acid were the best solvent and acyl donor,respectively.The reaction conditions were optimized by single-factor tests and an orthogonal experiment of four factors and three levels.The results were p-coumaric acid/C3 G molar ratio 30,enzyme load 35 mg/m L,reaction temperature 55 ?C and reaction time 144 h.The highest conversion of C3 G was 53.29%.2.The stability and antioxidant activity of C3 G and its p-coumaric acid modifid products(Mo-C3G)were investigated.Firstly,the stability of C3 G was conducted by studying the effect of different p H,temperature,redoxs and metal ions on the preserving rate of C3 G.The antioxidant activity of C3 G and Mo-C3 G was further assayed by detecting DPPH and superoxide anion free radicals scavenging activity,anti-lipid peroxidetive ability and total reducing power.The results showed that C3 G had higher preserving rate after molecular modification under high temperature and p H.The molecular modification of C3 G could improve stability in the presence of Cu2+,Mn2+ and H2O2,but,Fe2+ and Vc had no siginificant influence on the stability of C3 G and Mo-C3 G.The scavenging rate of DPPH and O2-,anti-lipid peroxidetive ability and total reducing power of Mo-C3 G were 95.39%、80.67%、68.74% and 0.37,respectively.And C3 G were 93.12%、75.26%、63.31% and 0.35,respectively.At the same concentration,the antioxidant activity of Mo-C3 G was higher than that of C3 G.3.The modulatory proliferation of C3 G and Mo-C3 G on probiotics was studied.The effect of C3 G and Mo-C3 G on different probiotics(Bifidobacterium adolescentis,Bifidobacterium infantis,Bifidobacterium bifidum and Lactobacillus acidophilus)was studied by detecting OD600 and p H of media.The results showed that OD600 and p H of C3 G and Mo-C3 G media were lower than that of control,suggesting C3 G and Mo-C3 G had proliferation effect,and Mo-C3 G had better prebiotics activity.C3 G and Mo-C3 G were utilized by probiotics,and thirteen metabolites including organic acid,alcohol and aldehyde were detected by GC-MS in the media containing C3 G and Mo-C3 G.Finally,the metabolic pathway of C3 G and Mo-C3 G was proposed based on the change of chemical structure of metabolites.4.The process and spray drying conditions of anthocyanins salts were studied.To investigate the effect of different wall material on encapsulation efficiency of anthocyanins salts,a wall material-dependent analysis was conducted,and the optimum composite wall material was hydroxypropyl-β-cyclodextrin and arabic gum.On the basis of single-factor tests,the process and spray drying conditions of anthocyanins salts were optimized by an orthogonal experiment of four factors and three levels and a verification test.The optimum process conditions of anthocyanins salts were proportion of core(hydroxypropyl-β-cyclodextrin/arabic gum)2:3,ration of core to wall 1:6,solid content 10% and emulsifier content 2.0%,and the encapsulation efficiency of anthocyanins salts was 69.44%.The optimum spray drying conditions of the anthocyanins salts were inlet air temperature 200 ?C,outlet air temperature 90 ?C,feed speed 3.0 L/h and homogeneous speed 11000 r/min,and the encapsulation efficiency of anthocyanins salts was 88.61%.Finally,C3G-S and Mo-C3G-S were prepared by using the optimal conditions,and the particle size distribution and surface microstructure of different anthocyanins salts were detected.The results showed that the particle size distributions of BRAE-S,C3G-S and Mo-C3G-S were similar to normal distribution,and characteristic particle size value decreased in the order of BRAE-S>Mo-C3G-S>C3G-S.SEM images revealed the major part of anthocyanins salts was small particles,but with a small amount of large particle.The anthocyanins salts were dried enough,and had complete structure.There were no cracks in the salts surface,and the encapsulation effect was good.