Study On Preparation And Antioxidative Activities Of Bamboo Shoot Peptides

Bamboo shoot contains rich nutriments, the content of protein (dry matter) is greater than 14%. The bamboo shoot protein was extracted from bamboo shoots, and further hydrolyzed to bamboo shoot peptides (BSPs), the optimal conditions were determined, the peptides were separated by ultra-filtration technology, and the antioxidative activity of bamboo shoot peptides was evaluated by chemical models.The optimal process for extraction of bamboo shoot protein from the bamboo shoots was studied by adding water, pH and tempreture. The optimal conditions were determined: ratio 1:4 for material to liquid, alkali pH9.0, acidic pH4.2 and tempreture 45℃. The content of bamboo shoot protein above 10kDa was occupied 84.30%.In order to improve the yield of bamboo shoot peptides (TCA-NSI) and the degree of hydrolysis (DH),the hydrolysis process of bamboo shoot protein by the Protamex and Papain was studied. Based on the single factorial design, orthogonal rotatable central composite experiment with four factors and five levels was designed, and the regression model was established.The optimal conditions were determined: enzymes ratio 1:2, pH7.0, temperature 58℃, proteases dosage 9000 U/g, substrate concentration 2% and time 179 min. Under these conditions, TCA-NSI was 70.69±0.57% and DH was 25.07±0.71%.Bamboo shoot peptides were separated by ultra-filtration technology to acquire oligopeptides with different molecular weight distribution. The effects of pressure, concentrations and temperature during ultra-filtration were studied. The results show that the optimum conditions of the first-degree ultra-filtration were determined: 6% peptides, pressure 20 psi, temperature 40℃. The optimum conditions of the second-degree ultra-filtration were 6% peptides, pressure 25 psi and temperature 35℃. After separation with ultra-filtration, the recovery rate of bamboo shoot peptides below 1 kDa was 69.51%.Bamboo shoot peptides (BSPs) was divided into four fractions (BSP-â… , BSP-â…¡, BSP-â…¢, BSP-â…£), the antioxidant activities of the BSPs and the four fractions were studied by six methods. Their activities were listed as BSP-â…£>BSP-â…¡> BSPs> BSP-â…¢>BSP-â… . The IC₅₀ of scavenging DPPH, ABTS and hydroxyl radical of BSP-â…£were 1.03±0.01%, 14.47±0.08% and 1.07±0.06%. The scavenging activities of DPPH and ABTS by BSPs and BSP-â…£were stronger than soybean peptides and peanut peptides, but the scavenging activities of hydroxyl radical by soybean peptides were stronger than BSPAs.