Research On Enzymatic Properties Of The Flora In Rice Wine Distiller’s Yeast And Its Application In Production

As a kind of special alcohol of China, rice wine is the most favorite tequila ofpeople, which is popular during festivals. Wine making has a long history, which is aprocess of microbes fermentation. Distiller’s yeast as an indispensable element,completes the produce of wine by cooperation of different species of microbes intraditional technological process. Distiller’s yeast made conventionally is an outcomeof microbes competing in raw materials, and microbes that can survive in theenvironment are conserved, accumulating large amount of metabolites and enzymes.Enzymes are a type of catalytic proteins that are produced by cells, which are neededby all activities of creatures. Microbes cultivation during wine making is to utilise thebiochemical reactions of microbial enzymes. Modern research on flora of rice winestays at the stage of isolation, identification and physiology and biochemistry,knowing little about enzymology and enzyme engineering. Advanced technology andtheory must be used to figure out the biological nature and fermentation metabolism,in order to stimulate the development of rice wine, and improve the quality of itsproduce.Cultivation, isolation, enzyme activity and gas chromatography are used in theexperiment, microbes stains separated are studied as follow:Enzymology of five strains of molds separated are studied, and the best culturingconditions for maltogenic amylase and liquefying enzyme producing are confirmed.The results show that dynamism of maltogenic amylase and liquefying enzyme ishigher when cultured in3d～5d or at pH5.8, and the best pH for them to exert ragesfrom5.2to7.0. Both enzymes show a tend of decline in activity when the alcoholdensity reaches more than60%.Enzymology of four strains of bacteria separated are studied, and the bestculturing conditions for diastasum diastace producing are confirmed. The study showsthat enzyme dynamism reaches the peak when cultivated in24～72h, and theoptimum reacting temperature is50～60℃, the optimum pH is around4.6. Ca²⁺ andK⁺have an obviously positive effect on the enzyme. Enzyme activity achieves themaximum at the ventilation of100ml and the substrate concentration of1.5%. Thisenzyme activity is higher than having been reported domesticly. Enzymology of one strain of yeast separated are studied, using the technology ofmicroorganism flat purification and26S rDNA sequence analysis, a strain of yeast hasbeen separated from distiller’s yeast. It has been identified as Brettanomyces. Byenzyme activity measurement, influence factors of producing esterifying enzyme ofthe strains are studied. The results show that, oliver oil, yeast extract, MgSO₄, Inliquid fermentation,28℃,150r/min constant temperature and oscillation training for36h, fermented liquid enzyme activity is the highest, which can reach16.3U/mL.With initial pH at7.0, outfit fluid amount at25ml, enzyme activity can reach thehighest level. In addition, insufficient or too much training time is detrimental toenzyme production improvement. Initial pH and dissolved oxygen affect strainsforming esterifying enzyme.Through small scale tests in laboratory and determination of flavoring substancein fermentation samples using gas chromatography, and it is made definite that thewine samples fermentated contain ethyl caproate, ethyl lactate, acetic ether, thedensities of which are0.096%,0.056%,0.040%respectively.The samples belong toLuzhou-flavor liquor.