Study Of "Guankou" Grape Rapid Oxidation Mechanism And Anti-oxidation Method

Guankou grape is a specialty of jianshi county of hubei province.It was found that guankou grape was brownd fastly in the brewing process.It is enzymatic browning or non enzymatic Browning In the brewing process led to fast browing was stuied based on the study of grape fermentation and Browning during the wine oxidation process.Based on "guankou grape" as the experimental material,Franco-American Hybrid grape goldfinger,Huang Mi and Vitis Vinifera species ze xiang,seedless white grapes for comparison.Catalytic efficiency and enzymology characteristics of polyphenol oxidase(PPO)from five different grape was compared.To explore theinfluence of pectinase to fast browing.Polyphenol oxidase(PPO)activity and regular of phenolics change was studied.The influence of sulfur dioxide to oxidition and the most suitable amount of sulfur dioxide was determined based on the polyphenol oxidase(PPO)activity and the regular of phenolics change.The primary conclusions were as follows:? The degree of browning of heating destroy enzyme fermented liquid was lighter than the normal fermented liquid.Reduce the amount of phenolics was lighter than the normal fermented liquid.Enzymatic browning play a important role in the browning process.? Theresults about the compared study of five diffrent grape enzymology characteristics showed that the affinity between Franco-American Hybrid grape and Vitis Vinifera grape existed Significant difference.difference existed when 4-Methylcatechol,catechin and caffeic acid as substrats.while the Catalytic efficiency to catechin and caffeic acid of "guankou grape" were higher than the other four grape obviously.Of the inhibitors tested,the most effective inhibitors were found to be ascorbic acid and sodium metabisulfite.The inhibition effect to other four grape were stronger than guankou grape when sodium metabisulfite as inhibitor.Optimum pH and optimum temperature of five grape PPO had no Significant difference.? The OD 420 nm was 0.265,0.282,0.348 and 0.420 when add 0mg/L,30mg/L,60mg/L and 100mg/L pectinase and the PPO activity was 30.01,34.12,38.02 and 42.37 U/(min·mL).Pectinase increased the PPO activity and then enhanced the browning reaction.? The OD 420 nm was 0.528,0.388,0.282 and 0.210 when add 0mg/L,30mg/L,60mg/L and 100mg/L sulfur dioxide and the PPO activity was 41.37,40.28,38.02 and27.73U/(min·mL).It could detected PPO activity until the end of fermentation when the content of Sulfur dioxide was 0mg/L.The PPO activity decresed to 0U/(min·mL)when fermentation time was 108,84 and 48 hour when add 0mg/L,30mg/L,60mg/L and 100mg/L sulfur dioxide.Sulfur dioxide inhibited the PPO activity and then inhibited the browning reaction.The strongest inhibitory effect when the sulfur dioxide concentration was 100mg/L.