Studies On Antioxidant Polypeptide Extracted From Abalone Viscera By Enzymatic Hydrolysis

The abalone is the famous and rare food in China, which is very rich in protein, iron, iodine, vitamin A and so on. Its nutrition is 7 times more than Australia walnut. Abalone viscera accounted for 20-30% of abalone weight, which is rich in protein and other nutrients. Because of the abalone’s high edible, medicinal value and high economic efficiency, the researches of abalone processing are more and more; however, abalone viscera with medicinal value become scraps. Extracting antioxidant peptide from abalone visceral is a good solution to the abalone visceral scraps problem. In addition, peptide can be used as functional nutrients which can effectively clear excess reactive oxygen free radicals of the body and can maintain normal functions and structures of cells and mitochondria.Besides of applications in the prevention and treatment of free radical-induced diseases and anti-aging, antioxidant peptide can be used as antioxidants in food processing industry.This experiment takes crude protein of abalone visceral as the experimental material.The polypeptide with antioxidant activity is extracted from abalone visceral by enzymatic hydrolysis, ultrafiltration dialysis and desalting methods. Meanwhile, the polypeptide’s antioxidant activity is measured in vitro and in vivo assay. This can provide theoretical and technical support to the utilization and development of the internal organs of the abalone.The results of this study are as follow:1.The alkaline protease is identified as the best hydrolytic enzyme from protease, trypsin, papain, pepsin and alkaline protease-by the index of the degree of hydrolysis and the hydrolysate’s reduction. Its optimized enzymatic process conditions:pH value is 10, enzymatic time is 5h, the hydrolysis temperature is 45℃, the enzyme dosage is 4500U/g, the substrate concentration is 13%.2.Determine the purified processing of the enzymatic hydrolysis: the hydrolysis liquid of the abalone visceralâ†' ultrafiltrationâ†' add acid to neutralizingâ†' desaltingâ†'freeze drying. The yield of polypeptide is 69.40%.3. Total antioxidant activity, scavenging effects of hydroxyl radical andscavenging ability of superoxide anion of two components in different molecular weights were measured to evaluate their antioxidant activities. The results are as follows:Antioxidant activity of antioxidant peptide in 0～3K in molecular weight in the abalone visceral protein is higher than one in 3K～10K.Antioxidant capacity of polypeptide in concentration of 1.94mg/ml is equal to Vc in concentration of 40ug/ml; Average hydroxyl radicals immunity of the polypeptide is lightly higher than the Vc in concentration of 40ug/ml; The average activity unit of superoxide is 186.18 μ/g. The extracts antioxidant peptide from abalone visceral protein have good antioxidant activity in vitro, because peptides in small molecular weight expose more active groups, which increase their antioxidant activity.4. Aging model, induced by D-galactose, and the index of activity of GSH, MDA and SOD in the liver and serum of the mice are used to explore the antioxidant activity of polypeptide in vivo.The results are as follows:SOD and GSH content in serum and liver in the positive control group and the high dose group were significantly higher than that of the aging group (p<0.05); MDA content in serum and liver is significantly lower than that of the aging group. SOD content in serum of middle dose group serum is significantly higher than the aging group. GSH and MDA content in serum and liver of middle dose group and low dose group-are not significantly significantly different with the aging group (p> 0.05).SOD content in liver of the middle dose group is not significantly different with the aging group(p> 0.05). The results indicated that vitamin C and the extracts antioxidant peptide from abalone visceral protein both can increase the antioxidant activity in aging mice induced by D-galactose, and the extracts antioxidant peptide can effectively prevent the body against the injury of oxidizing substances, and can improve the body’s resistance to oxidation vitality. The polypeptide has the antioxidant activity in the body and has a dose-dependent manner.