Mutation And Screening Of Optimal Oenococcus Oeni And The Effects On Wine Quality

Red wine has drawn more and more attention currently for its nutrition and healthyfunction. In the study, the contents of many chemical compositions of wine weredetermined during its fermentation process (about42days), then the effects of the strains(Oenococcus oeni C10and J2) on wine quality were researched. In order to get theoptimum strain with high malic acid-lactic acid conversion rate, the methods of UVmutagenesis, primary screening and secondary screening were carried out.The contents of seven kinds of chemical compositions (resveratrol, malic acid, lacticacid, total sugar, tannin and metal elements) in wine were determined during differentfermentation periods by different test methods, and the trends were analyzed to obtain thevariational rule during the brewing process.Malolactic fermentation (MLF) of different wine samples were induced artificially,and the results show that both the strains C10and J2can start up MLF, whose efficiency ishigher and the fermentation period is shorter compared with natural fermentation. Thecolour densities and the soft index of the wine samples fermented by C10and J2werehigher or almost equal to natural fermentation. The result indicates that the two strains canimprove the problem that the chroma reduction during MLF, and at the same time theyalso shorten the period of MLF fermentation under maintaining a soft mouthfeel. Theresult indicates that both the strains C10and J2have the characteristics and capabilities tobe the fermentation agent.The further research indicates that as strains of C10and J2being the original strains,the strain C10-1with positive mutation is obtained by using the methods of UV mutationand screening. The malic acid-lactic acid conversion rate of C10-1is38.81%, which issignificantly improved compared with those of original strains and other experimentalgroups. The colour density and soft index of the wine sample fermented by C10-1are thehighest meanwhile the reduction of the colour density during MLF can be avoidedeffectively and the wine taste is improved. The results of the experiments indicate thatC10-1has the potential to be the potent fermentation agent for wine secondaryfermentation.