Preparation And Research On Antioxidant Peptides From Hydrolysates Of Pacific Abalone (Haliotis Discus Hannai) Gonads

For a long time, the processing and consumption of the pacific abalone which was one ofthe important marine shellfish were mainly pleopods. In the processing of the abalone, abalonevisceras are15-25%of the total weight，which were not fully utilized. Using the byproductsresulted from abalone as raw materials prepared bioactive peptides, which had antioxidantfunctions, and developed functional foods, which aimed to transform these biological wastes tovalue-added products. This study used abalone gonad as raw materials, prepareing antioxidantpeptides by controlling enzymatic hydrolysis, and used three kinds of chemical models in vitro(DPPH radical scavenging activity, Hydroxyl radical scavenging activity and Fe2+reducingpower) comprehensively to evaluate the antioxidant activity of abalone gonad small peptides,while using ultrafiltration, gel chromatography, reversed-phase high-performance liquid(RP-HPLC) separation technology to separate, purify and determine molecular weight of abalonegonad small peptide.It was hydrolyzed with five commercially available proteases, including papain, neutralprotease，alkaline protease，trypsin，protease. The results were evaluated with SDS-PAGEanalysis and the DPPH radical scavenging activity. Papain and protease are the better enzymefrom the screening process. Then, the hydrolysis condition of two kinds of enzymes wasoptimized in this study. Finally, two kinds of enzyme solutions were determined: the conditionsof optimized double enzyme hydrolysis process are: the first enzyme hydrolysis of the papain,enzyme dosage of0.5%(3975U/g), temperature of60°C, reaction time of2h, pH of7, ratio ofsolid to liquid of1:10, the second enzyme hydrolysis of protease, enzyme dosage of1%(3670U/g), reaction time of2h; The conditions of single enzymatic hydrolysis process are: papainenzyme dosage of2%(15900U/g), temperature of50°C, pH of6, solid-liquid ratio of1:10,reaction time of2h.The antioxidant activity of abalone gonad small peptides using single enzymatic methodwas evaluated by three kinds of chemical model in vitro. The results showed that: in the range of0-10mg/mL concentration, the DPPH radical scavenging activity of abalone gonad hydrolysates was stronger, its IC50value was5.85mg/mL; Hydroxyl radical scavenging activity of abalonegonad hydrolysates was equivalent to that of Vc, the IC50values of abalone gonad hydrolysatesand Vc were0.7mg/mL and0.5mg/mL, respectively; while the abalone gonad hydrolysates alsohad a certain reducing power, the AC0.5value was7.8mg/mL.Using30kDa and5kDa ultrafiltration membrane, Sepahdex G-25, Sephadex G-15,Superdex peptide10/300GL and RP-HPLC separation technology separated and purifiedabalone gonad hydrolysates resulted from double enzyme method and single enzyme method toprepare antioxidant peptide. According to the RP-HPLC analysis, the single componenthydrophobic ability of single enzyme method and double enzyme method are different. Thesingle component using single enzyme method was mainly belongs to the hydrophobiccomponent, while the single component using double enzyme method was mainly hydrophilicfractions. The single component molecular weight using double enzyme method is656Daobtained by MS analysis.In general, this study established a process for the preparation of antioxidant peptides fromabalone gonad and got the better of antioxidant products while providing a data reference for theindustrial production of antioxidant peptides and applications.