Studay On Antioxdative Peptides Derived From Buffalo Milk Proteins

The buffalo milk is a kind of high-quality local characteristics milk, which has a higher protein content than the Holstein milk, so it has attracted extensive attention.However, at present there are a few reports on it, and only several studies on physical and chemical indicators have been reported. The using of buffalo milk protein preparing active peptides research were rarely, Only seeing about the using of buffalo casein to preparae the phosphoric acid peptide, but the research about the preparaing antioxidant activity peptides of buffalo milk was not seem yet. For this reason, the paper carried out the research of the preparation antioxidant activity peptides derived from buffalo milk proteins,antioxidant activity of the buffalo milk proteins hydrolysates and the purification on buffalo milk casein hydrolysates.First, casein and whey protein was separated from bufflao milk,then using hydrolysis degree, DPPH radical-scavenging capacity and reducing power as detection indicators,alcalase, neutrase, papain, trypsin and pepsinto hydrolyzed buffalo milk casein and whey protein were compared to prepare antioxidant peptides.It was found that the hydrolysates with neutrase had the best effect of reducing ability and scavenging to DPPH free radical, and the reducing ability and DPPH radical-scavenging capacity of the caseinhydrolysates was up to0.445and23.344%,respectively,while the reducing ability and DPPH radical-scavenging capacity of the whey protein hydrolysates are up to0.376and37.819%,respectively.The technology for preparing protein hydrolysates from casein was optimized with one-factor-at-a-time experiments and response surface methodology (RSM). The optimum technological parameter for preparing antioxidant peptide of buffalo milk casein with neutrase was obtained as:pH7.4at45.0℃,enzyme/substrate ratio8800U。g-1and the hydrolysis time4.0h.The optimum technological parameter for preparing antioxidant peptide of buffalo milk whey protein with neutrase was obtained as:pH7.4at50.5℃,enzyme/substrate ratio4300U。g-1and the hydrolysis time5.Oh.Using5vitro antioxidant models to evaluate buffalo milk protein peptides antioxidant activity function, The results show that the buffalo milk protein hydrolysates all displayed strong antioxidant activity and a significant amount of activity relationship.This showed the buffalo milk protein hydrolysates was good electronic donors and hydrogen donor, and it could significantly suppress lard system of peroxidation and clear superoxide radical, hydroxyl radicals.The buffalo milk casein hydrolysates were ultrafiltrated consecutively by a poly membranes with the molecular cut off of10kDa and5kDa.The optimum conditions of the ultrafiltration were:pressure0.20MPa, temperature30℃and time20min.After ultrafiltration three components were obtained, and molecular weight of less than5kDa components had the highest antioxidant activity with the reducing ability increasing by41.2%than mixture fraction before ultrafiltration and DPPH free radicals clearance improving38.71%.The molecular weight of less than5kDa components was separated and purificated by Macroporous resin, Glucan gel chromatography G-25and Glucan gel chromatography G-15. After the Sephadex G-15elution, two components peak were got, through determining the DPPH free radicals clearance, we found the peak I had the strongest antioxidant activity, DPPH free radicals clearance was up to59.830%%.