Studies On The Technology Of Continuously Hydrolyze Peanut Protein And Antioxidative Activity Of Peanut Peptide

Peanut proteins, which have wide source and low price, are generally used in the food processing. In this study, peanut proteins as the raw material, were continuously hydrolyzed by Alcalase protease in the enzyme membrane reactor. This paper main studied antioxidant activity in the vitro and vivo, preliminary purification of peanut peptides. And, amino acids and molecular weight distribution of the various purified fractions were further researched. This study can provide theoretical bases for the industrial continuous hydrolysis of peanut protein and functional foods application of peanut peptides. So this research also increased the added value of peanut protein. The main research content and results are following:1. Study on the technology of continuous hydrolysis peanut protein. Using hydrolysis degree (DH) as an indicator, peanut proteins were hydrolyzed by Alcalase protease in the enzyme membrane reactor. Through single-factor tests, they select test factors and the level of test factors, and determine the operating pressure of 0.02MPa. And the four factors (pH, temperature, substrate concentration and protease dosage) and three levels response surface methodology (RSM) test were designed. It was found that the optimum condition was pH 9.6, temperature 54℃, substrate concentration 2% and protease dosage 7440u/g. Under the optimum condition, practical DH is 26.13%.2. Research on the vitro antioxidant activity of peanut peptides. The reducing capacity, DPPH-scavenging capacity, ABTS+·scavenging capacity and O2-·scavenging capacity of peanut peptides were studied. The results showed that peanut peptides had certain reducing capacity and different scavenging effects on different free radicals. The reducing capacity and free radical-scavenging capacity were increased with the increase of peanut peptide concentrations.The scavenging capacity of half-inhibitory concentration (IC50) value was determined on the DPPH·free radical of peanut peptides and O2-·free radical of peanut peptides. Peanut peptides on the DPPH·free radical scavenging capacity of IC50 value was 0.65mg/ml, on the O2-·free radical of IC50 value was 24.23mg/ml. 3. In order to study on the vivo antioxidant activity of peanut pep tides, using D-galactose induced aging mice as a model, the contents of malondialdehyde(MDA) and glutathione(GSH), the activities of superoxide dismutase(SOD) and glutathione peroxidase(GSH-Px) in the serum, liver and heart of each groups mice were determined. The results showed:compared with the model group, the high doses of peanut peptides could significantly(p<0.01) reduce the MDA contents in the serum, live and heart of aged mice induced by D-galactose. It also could significantly(p< 0.01) increased the activities of serum, live and heart SOD and GSH-Px, which increase(p<0.05) the contents of GSH. So peanut peptides have well vivo antioxidant activity.4. Peanut peptides were separated and purified by sephadex G-15, which got two fractions (ⅠandⅡ). Then, the amino acids and molecular weight distribution of these fractions were further researched. Through testing the DPPH·and O2-·radical scavenging, the antioxidant activity of fractionⅠwas higher than fracitionⅡ. Then analysis of amino acids between two fractions, they were large difference among the contents of different kinds of amino acids. FractionⅠhad the hydrophobic amino acid nearly 50%, much higher than fractionⅡ. Found in the molecular weight distribution, the peptides of fractionⅠandⅡconcentrated in 3000-5000Da. The molecular weight distribution of fractionⅡwas more dispersed than fractionⅠ...