Effects Of High-pressure Microfluidization Treatment On Structural Characteristics Of Kidney Bean Polysaccharide And Its Capability To Inhibit Digestive Enzyme Activity

Kidney bean(Phaseolus vulgaris),including red kidney beans,white kidney beans,speckled kidney beans and red speckled kidney beans,is rich in nutrients such as protein,phenols and functional carbohydrates.Kidney bean polysaccharides are functional carbohydrate with various biological activities,such as lowering postprandial blood glucose and insulin response,reducing the risk of cardiovascular disease,etc.However,there are few reports about the fine structural characteristics of kidney bean polysaccharides.Therefore,the basic structures of red kidney bean polysaccharide(RKBP)and white kidney bean polysaccharide(WKBP)were studied in this study.Effects of dynamic high pressure microfluidization(DHPM)on basic structural characteristics,rheological properties and solid morphology of the two kidney bean polysaccharides were evaluated.Futhermore,the inhibition effect of RKBP on digestive enzymes were assessed in vitro before and after DHPM treatment.The main research contents and conclusions are as follows:1.Extraction,separation,purification and structural characterization of WKBP.WKBP was purified by weak anion exchange chromatography column(DEAE-Sepharose Fast Flow)and gel permeation chromatography column(SephacrylTM S-400 HR)to obtain three major fractions(WKBP-P2,WKBP-P3 and WKBP-P4)having high yield.Physiochemical properties and structural characteristics of WKBP-P2,WKBP-P3 and WKBP-P4 were characterized.All of three polysaccharide fractions were high in glucuronic acid content and low in protein content.WKBP-P2 was mainly composed of GalA(26.3 7%),Ara(14.00%),Xyl(10.65%),Gal(7.18%)and a small amount of Rha(1.58%).WKBP-P2 contained arabinan and RG-I type pectin.WKBP-P3 was mainly composed of GalA(24.67%),Ara(13.33%),Xyl(15.53%),Gal(11.56%),Rha(1.33%)and GIcA(1.56%).WKBP-P2 contained arabinan,XGA type and RG-II type pectin.WKBP-P4 was mainly composed of GalA(28.56%),Xyl(9.50%),Gal(4.51%),Ara(4.24%)and a small amount of Rha(1.40%).WKBP-P4 was HG type pectin.2.Extraction,separation,purification and structural characterization of RKBP.RKBP was purified by strong anion exchange chromatography column(Q-Sepharose Fast Flow)and gel permeatiol chromatography column(SephacrylTM S-400 HR)to obtain two major fractions of RKBP-P1 and RKBP-P2.Physiochemical properties and structural characteristics of RKBP-P1 and RKBP-P2 were characterized.Both of the two polysaccharide fractions were high in glucuronic acid content and low in protein content.RKBP-P1 was mainly composed of Ara(20.82%),Xyl(18.66%),GalA(17.67%),Gal(11.29%),Fuc(8.47%)and a small amount of Rha(0.34%).RKBP-P1 contained HG type pectin,arabinan and a small amount of XGA type pectin.RKBP-P2 was mainly composed of Ara(28.50%),Gal(22.93%),Xyl(11.38%),GalA(11.11%),Fuc(1.50%),Rha(1.45%)and GlcA(1.59%).RKBP-P2 had AG-? type pectin with main chain,which was composed of 1,3-Galp with substitution of Araf at O-6.RKBP-P2 also contained a certain proportion of arabinan with the main chain,which was composed of 1,5-Araf(17.08%)with substitution at O-2/O-3.RG-? type pectin also existed in the RKBP-P2.3.Effects of DHPM on the basic structural characteristics,rheological properties and solid morphology of kidney bean polysaccharide were systematically studied under different pressure.The results showed that the effect of DHPM on the basic physiochemical properties and molecular weight distribution of WKBP was not great.DHPM treatment could increase the sugar content of RKBP.The viscosity and molecular weight of RKBP decreased significantly with the increase of treated pressure.The monosaccharide composition and solid morphology of RKBP were affected by the DHPM treatment,while thermal stability,infrared spectrum and 1H NMR of RKBP were not obvious.The effect of DHPM treatment on the sugar content and monosaccharide composition of RKBP may be caused by the precipitation of impurity and degradation of branched chains.4.Inhibition effects of RKBP(before and after DHPM treatment)on enzyme activities were studied in virto,which included ?-glucosidase,?-amylase and lipase.The results showed that RKBP had little effect on ?-amylase inhibition.DHPM treatment of different pressures could not improve the inhibition effect of RKBP on?-amylase activity.RKBP had no obvious inhibition effect on ?-glucosidase and lipase activities.