Preparation And Activity Evaluation Of Bile Salts Adsorptive Oligopeptides From Tartary Buckwheat

Fagopyrum tartaricum Gaertn not only contains much nutrients and bioactive substances, such as protein, fat, flavonoids and fatty acids, but also has the ability to prevent high blood lipids, hypertension and other diseases. In this study, the protein of tartary buckwheat was chosen as the research object, and the degree of hydrolysis and the adsorption effect of bile salts(sodium cholate, sodium deoxycholate, sodium taurocholate) were chosen as indicators. The conditions of hydrolysis were optimized through response surface methodology. The key factors in the process of hydrolysis and their influence were investigated. The bile salts binding activity of fractions which were separated from hydrolysate by modern separation technology were studied, which can provide theoretical reference for the mass production of tartary buckwheat oligopeptides with highactivity. The antioxidant activity of tartary buckwheat oligopeptides was evaluated through antioxidant assay (FRAP and ABTS assay) in vitro, which can provide basic test data for the research of tartary buckwheat oligopeptides. The main results are as follows.(1)The tartary buckwheat protein was hydrolyzed by Protease A-2SD, Protin SD-NY 10, Thermoase PC10F, Protin SD-AY10, Proleather FG, Protamex and Papain, respectively. It turns out that Protease A-2SD was the proper enzyme.(2)The proper conditions to hydrolyze tartary buckwheat protein were measured by single factor test. It is as follows. Protease A-2SD dosage 5000-7000U/g, pH 6.5?7.5, reaction time 120-180min, temperature 45?55?, substrate concentration 8?12g/L.(3)The DH regression model was established by response surface methodology. It is as follows. DH (%)=-1.43+1.02*10-3Xi-0.54X2+0.086X3+0.35X4+0.076X5.The optimum hydrolysis conditions for preparation of tartary buckwheat oligopeptides were measured. It is as follows. Protease A-2SD dosage 6990U/g, pH 6.5, reaction time 180min, temperature 55?, substrate concentration llg/L. The DH can reach 37.82% in that way.(4)The optimum sample size, flow rate and column height were 2.0mL, 0.3mL/min and 55cm, respectively. It were measured through the optimization of Sephadex G-25 gel chromatography conditions. GFC-1, GFC-2 and GFC-3 can be separated from tartary buckwheat protein hydrolysate.(5)The regression models of bile salts adsorption activity of tartary buckwheat protein hydrolysate were established. They are as follows. SC(%)=2924.25+0.012X1-244.60X2+0.35X3-83.02X4+11.09X5-1.28*10-6X12+16.23X 22-1.03*10-3X32+0.82X42-0.54X52; SDC(%)=3274.81-0.10X1-146.22X2+1.12X3-89.03X4-40.46X5+9.93*10-7X12+0.71X22 +3.19* 10-5X32+0.85X420.12X52+0.011XiX2+2.34*10-4XiX4-0.043X2X3+0.39X2X4+4. 57X2X5-0.016X3X4+0.12X4X5; STC(%)=1733.31-0.048X1-93.20X2+1.40X3-46.39X4-14.46X5+1.55*10-6X12+3.68X22-1.64*10-3X32+0.42X42+0.30X52+3.62* 10-3X1X2-5.08*10-6X1X3+1.85*10-4*X1X4-3.36* 10-4X1X5-0.070X2X3+0.22X2X4+1.16X2X5-0.010X3X4+0.013X3X5+5.5*10-3X4X5?(6)The test results of bile salt binding show that the maximum values of binding SC(60.4%)?SDC(90.4%) and STC(67.6%) were obtained under the conditions: Protease A-2SD dosage 5182U/g, pH 6.5, reaction time 160min, temperature 45 ? and substrate concentration 8g/L. The binding rate of SDC and STC were higher than tartary buckwheat protein (81.32%?21.18%). The binding rate of SC, SDC and STC were higher than ultrafiltrate (51.8%?67.3%.27%) and oligopeptides (GFC-1, 40.72%?32.22%?31.14%?GFC-2,46.86%?39.62%?28.6%;GFC-3,35.27%? 31.39%?19.92%) separated by Sephadex G-25.(7)The test results of FRAP and ABTS show that the reducing capacity of tartary buckwheat protein, tartary buckwheat protein hydrolysate, ultrafiltration fractions of tartary buckwheat protein hydrolysate and tartary buckwheat peptide were 10.5?g Trolox/mL,18.9?g Trolox/mL,33.7?g Trolox/mL,22.5?g Trolox/mL,13.2?g Trolox/mL and 27.8?g Trolox/mL. It also show that the radical scavenging capacity of tartary buckwheat protein, tartary buckwheat protein hydrolysate, ultrafiltration fractions of tartary buckwheat protein hydrolysate and tartary buckwheat peptide were 261.3?g Trolox/mL,843?g Trolox/mL,783?g Trolox/mL,773.4?g Trolox/mL, 580.8?g Trolox/mL and 872.6?g Trolox/mL.