Font Size: a A A

Study On The Enzymatic Preparation Of Antioxidant Peptides From Rice Residue

Posted on:2015-12-23Degree:MasterType:Thesis
Country:ChinaCandidate:M ShiFull Text:PDF
GTID:2271330482966812Subject:Agricultural Products Processing and Storage
Abstract/Summary:PDF Full Text Request
In this paper, the rice residue was used as raw material, and the pretreatment, enzymatic extraction of the antioxidant peptides, anti-oxidative activity, separation and purification on raw materials were systematically studied, to make full use of rice residue resources and produce the high-grade antioxidant peptides, thus, to provide a powerful basis and technical support for the depth exploitation and utilization of rice resources.The main results are shown as follows:1. Effect of ultrasonic pretreatment on the enzymatic preparation of antioxidant peptides from rice residue. Taking the DPPH free radical clearance as evaluation index, it studied the effects of ultrasonic pretreatment of protease, raw material and enzymatic hydrolysis process on enzymatic hydrolysis. The results showed that three types of ultrasonic could effectively promote enzymatic hydrolysis, improve the DPPH free radical clearance of product. The best effect was ultrasonic pretreatment on raw material. The optimal ultrasonic pretreatment conditions were ultrasound power 150W at initial temperature 50℃ for 15min. Under the optimum conditions, the DPPH radical scavenging rate was 75.41%, and the yield of the purified peptides was 35.55%, which was increased by 39.86% compared with values by the traditional method.2. Study on enzymolysis conditions of rice residue after ultrasonic pretreatment. Six proteases (neutral protease, trypsin, flavourzyme, papain, alkaline protease and pepsase) were typically selected and hydrolyzed under appropriate conditions. The degrees of hydrolysis (DH), DPPH radical scavenging rate and the EC50 of all the proteases were obtained for comparison, to filter out neutral protease as the optimum protease. Herein, taking the DPPH free radical clearance as evaluation index, determined the best extraction process:the concentration of substrate was 3%, the quantity of protease was 2800U/g, pH6.0 at40℃. Under the optimum conditions, the DPPH radical scavenging rate was 83.55%.3. Study on antioxidant activity of antioxidant peptides. By using different antioxidant assays in vitro antioxidant system to evaluate the antioxidant capacity. The antioxidant properties of antioxidant peptides from rice residue results showed that the peptides had a better scavenging activity on the hydroxyl radical, superoxide anion radical and DPPH, and scavenging activity presented a linear relationship with concentration, of which the IC50 is 0.447mg/mL,0.339 mg/mL and 3.633mg/mL respectively. It also showed that antioxidant peptide can suppress the oxidation in linoleic acid system. Moreover, with the increase of concentration, the antioxidant activity becomes more obviously.4. The separation and purification of antioxidant peptides. Two eluting peaks A and B were obtained from antioxidant peptide samples after chromatography by sephadex chromatography (G-25). A showed higher rate of DPPH free radical scavenging, which was 84.23%. According to the molecular weight determination of A and B, the molecular weight was 1259Da and 430Da on the basis of regression equation. It had rich types of amino acid containing in rice peptide which was up to 18, and it was very nutritional as well.
Keywords/Search Tags:Rice residue, Protease, Antioxidant peptide, Ultrasonic wave
PDF Full Text Request
Related items