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Study On The Relationship Between The Hydrolysis And Oxidation Resistance Of Protein

Posted on:2017-04-29Degree:MasterType:Thesis
Country:ChinaCandidate:T T WangFull Text:PDF
GTID:2180330503467055Subject:Biochemistry and Molecular Biology
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Antioxidant is usually the sign of physical self protection. Many material of foods have the function of antioxidant. Protein is one of the most important components in the food and the protein can be hydrolyzed into polypeptide in vivo. Research on the oxidation state of the polypeptide can get more information about the physiological function of the protein and make a good foundation for the preparation of antioxidant peptides. Three kinds of protein, bovine serum albumin, water-soluble soy protein and ovalbumin, which were common in food had be studied and protein all hydrolyzed by trypsin. The relationship between the degree of hydrolysis and oxidation resistance from the hydrolysis. Conclusions as follow.The results showed that the optimum temperature of the reaction between BSA and trypsin is 40 ℃ and the mass ratio of BSA and trypsin is 20:1. The capacity of scavenging free radicals increased significantly with the process of the hydrolysis. Within the first 80 min reaction, the degree of hydrolysis and radical scavenging capacity has a significant growth. The degree of hydrolysis increased to 15.1%, the free radical scavenging rate from 29.91% to 50.12%, increased 20.21%. In the subsequent hydrolysis, the degree of hydrolysis of the polypeptide is increasing, but the increase is slow, finally got stable, the free radical scavenging capacity began to decrease, indicating that excessive hydrolysis is not conducive to the improvement of oxidation resistance. The analysis of the peptides from hydrolysis by SDS-PAGE, DH and the degree of hydrolysis of peptides performed by calculation is consistent; as the peptides which the molecular weight is about 25-28 KD were be hydrolyzed, oxidation resistance increase, polypeptide segment having presumed unexposed antioxidant activity groups. Speculated that the peptides with antioxidant activity group which unexposed.Extraction of water soluble proteins of soybean powder is 8.738% by using of degreasing; the pretreatment of water-soluble soybean protein let the reaction between trypsin with water-soluble soybean protein be carried better. Optimum conditions for pretreatment temperature 85 ℃, the processing time of 20 min; With the hydrolysis of the water-soluble soybean protein processing, the degree of hydrolysis(DH) increasing, the rate of hydrolysis increased first and then decreased, then be stabilized gradually, but the capacity of scavenging free radical increasing with the increasing of the DH. Enzyme(0.01 g) was added in water-soluble soybean protein(50 mL), reaction continued for 90 min, its degree of hydrolysis is 2.682%, the rate of scavenging free radical can reach 46.53%, and excellent oxidation resistance of soybean peptide can be obtained from the hydrolysis reaction under these conditions.In the hydrolysis reaction, ovalbumin and trypsin, as hydrolysis processed, the degree of hydrolysis increases, the amount of substrate reducing gradually. With the increase of the amount of enzyme was added in the reaction, the rate of hydrolysis in the initial period is higher, the substrate of the reaction were be hydrolyzed more. The degree of hydrolysis for the reaction between trypsin(15625 U) and the substrate(ovalbumin 1 g) tends to be stable after the reaction last for 5 hours, the degree of hydrolysis was more than 25%. In this degree of hydrolysis, the capacity of scavenging free radical was 23.87% maximum. With the processing of the hydrolysis, for the degree of hydrolysis, the speed of rising became slow and the capacity of scavenging free radical had the same situation. Therefore, the appropriate hydrolysis can improve the antioxidant activity of egg albumin.
Keywords/Search Tags:Trypsin, bovine serum albumin, water-soluble soy protein, ovalbumin, the degree of hydrolysis, antioxidant, radical, polypeptide
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