Study On Seperation And Purification Of Rice Antioxidantive Peptides And Its Properties

Since Harman put forward the free radical theory, it is recognized that free radical oxidation of the human body have relation to human aging and many diseases, so people are increasingly concerned about anti-oxidants. But at present, most anti-oxidants are chemical compounds such as tert-butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT);Although these chemical effects of antioxidants have good results, they are potentially toxic to humans. In recent years, people ture their eyes to natural antioxidants, such as ascorbic acid, a-tocopherol, polyphenols, and soybean peptides obtained by soybean protein enzymed.Recent studies have found that antixoxidative rice peptides also have a strong function of inhibition of biological macromolecules peroxidation and free radical removal, and antioxidant activity of these peptides are often stronger than that of protein and amino acids, and has low toxicity and high efficiency.It is expected to use these antioxidant activity peptides to develop new functional foods and health productsIn this peper, preparation process of rice antioxidant activity peptide are optimization, and using response surface analysis method to get the best combination of ultrasonic treament process parameters.Through different in vitro systems,study the alkaline protease hydrolysates of rice antioxidant activity to provide the basis for further separation, purification and study.By in vitro digestion, evaluate the influence of digestion on rice antioxidant activity peptides. And then after further separation and purification, obtain several high antioxidant activity peptide fragments.Now the main results and conclusions are summarized as follows:1,select the ultrasonic power, ultrasonic treatment time, initial temperature of ultrasonic treatment to do 3 factors and 3 levels response surface experiment, then using SAS procedures for regression analysis of experimental data, obtain the best extraction parameters of the model:ultrasonic power 1750W, ultrasonic processing time 30min, the initial temperature of ultrasonic treatment 40℃, the DPPH radical scavenging rate is forecast to reach 78.2%.To verify the above experimental parameters by three parallel determinations, the DPPH radical scavenging rates of antioxidant peptide were:76.0%,75.8% and 77.4%,At this point the concentration of antioxidant peptides were 1.5037,1.5163 and 1.5085 mg/mL, DPPH radical scavenging average of 76.4%, the average concentration of antioxidant peptide was 1.5095 mg/mL,it is a satisfactory results.In these conditions, antioxidant peptide yield from 31.6% increased to 42.2%.2. This chapter uses 5 antioxidant activity detection methods, which include inhibition of lipid oxidation method, free radical scavenging ability method and determination of reducing power method, more comprehensively reflect the antioxidant capacity of rice peptides.And have a comparetion between antioxidant capacity and Vc, with the high concentration of 20.00～50.00mg/mL, the-OH scavenging of rice peptides and Vc are considerable, but in other free radical concentration and removal of other situations, the ability of rice peptides are less than Vc.In general, within a certain range, the antioxidant capacity of rice peptides, have relation to concentratio-n.3. After using Sephadex SephadexG-25 for the initial separation and purification, found a small peptide which molecular weight 132.7～1153.9 occupying a large proportion,it made a foundation for further separation and putification.4. Using SP-Sephadex C-25 as an ion exchange chromatography media, pH4.0, 0.02mol/L HAc-NaAc buffer solution for the initial flow rate of 120mL/h, NaCl (0～1mol/L) gradient elution, rice alkaline protease hydrolysis products NHREP are well separated, mixed peptide fraction was separated out of the seven compo nents(AG), component F, the strongest scavenging DPPH-(80.09±1.22%).5. Using Sephadex G-15 gel chromatography in turn divided fractions F into four components F1,F2, F3 and F4. And the various components were detected scavenging DPPH-.The results showed that fraction F3 showed strongest scavenging DPPH·(up to 77.64%).6. Through in vitro digestion process, measured DPPH·scavenging ability of rice peptide to evaluate the influence of in vitro peptide digestion process on rice peptide antioxidant capacity.After human body simulation digestion, and finally in the dialysis fluid, the highest clear rate of rice peptides scavenging DPPH·can reach 45.53%.This provided a good foundation for follow-up of rice peptides in vivo experiments, and established a rice peptides in vitro digestion experiment flowchart.