The Antioxidant And Antibacterial Activity Of Purple Wheat Bran Peptides

In recent years, natural antioxidants have gradually become a research hotspot for its own security and unique nutritional value in food industry. Bioactive peptides hydrolyzed by proteases from protein are natural antioxidants; these peptides have many biological activities such as antioxidant, antibacterial and anti-hypertension.Wheat bran is rich in protein; it is a kind of natural protein resources. We can get bioactive peptides by hydrolyzing wheat bran protein with proteases. In this study by determining the antioxidant activity and antibacterial activity of these peptides, we are aiming to screen a wheat bran peptide with strong antioxidant and antibacterial activity, and provide theoretical basis for wheat bran peptides. The main contents and results are as follows:1, Extract protein from the four kinds of wheat bran (SDAU purple wheat 1, Jimai 22, Yannong 19, Linmai 4), respectively, wheat bran peptides can make by hydrolyzing wheat bran protein with five kinds of enzymes (pepsin, trypsin, alkaline protease, neutral protease, papain). Concentration of wheat bran peptides were measured with BCA method, then vitro antioxidant index (DPPH radical scavenging capacity, the total reducing power, copper ion chelating ability) of these peptides were measured, we found purple wheat bran peptide hydrolyzed by trypsin showed strong vitro antioxidant activity.2, Purple wheat bran peptide hydrolyzed by trypsin was decolored by activated carbon, using decoloring rate and loss rate of peptides as index, the decoloring process after optimization was:decoloring time 30 min, decoloring temperature 30℃, activated carbon dosage 1.5% (w/w), decoloring pH6.0, under this condition, the decoloring rate was 53.45%, the loss rate of peptides was 33.54%. Then we determined the antioxidant activity and minimum inhibitory concentration (MIC) to four kinds of bacteria (Escherichia coli, Bacillus subtilis, Staphylococcus aureus and Salmonella) of decoloring hydrolyzate, and found the hydrolyzate after decoloring still showed strong antioxidant activity and antimicrobial activity.3, The degree of hydrolysis (DH) of purple wheat bran peptide hydrolyzed by trypsin was determined, and results showed that the degree of hydrolysis was 15.4% at 1h, and there was almost no increase with growth of time, this indicates that the enzyme and substrate protein response has been much fully at 1h.4, We segmented purple wheat bran peptide by using the method of ultrafiltration and get four kinds of peptide solution (>10KDa、5-10KDa、3-5KDa、<3KDa), then we determined the antioxidant activity of different peptide solution, the molecular weight<3KDa solution showed the strongest antioxidant activity, the molecular weight>10KDa solution showed the worst antioxidant activity.5, We separated and purified purple wheat bran peptide molecular weight<5KDa solution by using Sephadex-LH-20, then detected protein content at 280 nm wavelength and collected 2 protein elution peak. We determined the 2 protein elution peak’s antioxidant activity and minimum inhibitory concentration (MIC) to four kinds of bacteria, both of the two peaks showed strong antioxidant capacity and antimicrobial activity.