Screening Of Wickerhamomyces Anomalus And Its Effect On The Flavor Of Rice Wine

Rice wine is one of the traditional brewed wines in China and is favored by the public for its unique flavor.Wickerhamomyces anomalus was a common dominant yeast in rice wine yeast,yellow rice wine yeast and white wine yeast,which had an important influence on the sensory and flavor of rice wine.The tolerance,physical and chemical properties and flavor substances of W.anomalus were analyzed in this experiment.To explore its effect and influence on rice wine fermentation.In the flavor substances produced by fermentation,higher alcohol has an important contribution,but the excessive content of higher alcohol will make the wine body produce bitter taste and other bad flavor,so in this experiment,in the optimization of combined fermentation process,higher alcohol is taken as one of the evaluation criteria.On the basis of this process,the selected W.anomalus was fermented with Saccharomycopsis fibuligera and Saccharomyces cerevisiae.Rice wine with high sensory score,rich flavor substance and low advanced alcohol content was brewed.In this experiment,19 yeast strains were isolated from baiyun Fermented grains by dilution coating method,and 6 species of 5 genera were identified by sequencing.The largest was W.anomalus at 42.10%.Tolerance analysis showed that W.anomalus was weak in acid resistance,and W.anomalus had strong ethanol tolerance at 0%to6%,and had strong growth ability in rice wine fermentation.The flavor and physicochemical properties of 8 W.anomalus cultured in experiments and 5 W.anomalus cultured in laboratory were analyzed.It was found that the capacities of producing ethyl acetate and phenylethanol of W.anomalus LL-7 from different sources were significantly different.And the ethyl acetate production capacity is3303.03 mg/L,benzene ethanol production content is 7.65 mg/L.The combination fermentation of W.anomalus LL-7 was conducted,and the physical and chemical properties and gas phase results of the fermentation broth were analyzed.The combinations with W.anomalus,S.fibuligera,and S.cerevisiae in the same proportion were selected as the research objects,and the higher alcohol content and sensory score were used as screening indexes.The optimal fermentation parameters were determined by single factor experiment and response surface methodology:inoculation amount of 3×10~6cfu/m L,post-fermentation temperature of21℃and post-fermentation time of 2.5 days.The rice wine prepared under the optimal conditions was clear and transparent,with moderate sour and sweet taste,full flavor,high alcohol content of 153.1 mg/L and sensory score of 90.1.After optimization,higher alcohol content decreased by 7.2%and sensory score increased by 2.8 points.This study provided a new way to improve the quality of liquid rice wine brewing.The growth curves of THE secondary seed liquid of W.anomalus LL-7 were measured.The optimal fermentation conditions of W.Anomalus in liquid molasses medium were 170 rpm and 28℃for 24 h,and the total number of yeast was 5.01x10~9cfu/m L.By centrifugation and vacuum freeze-drying methods,the viable number of abnormal Wickham active dry yeast was 3.1×10~9cfu/g,the viable rate was 62.2%,and the water content was 11.6%.The yield of liquid fermentation yeast was 7.89 g dry yeast/L.GC-MS analysis and liquid chromatography analysis showed that there was no significant difference in flavor substance content and flavor substance type between active dry yeast and W.anomalus LL-7 liquid fermentation.Combined fermentation of rice wine using active dry yeast prepared by W.anomalus LL-7 and active dry yeast prepared by buckles and Saccharomyces cerevisiae showed that W.anomalus yeast could significantly improve the ethyl acetate production capacity of combined fermentation.The combination fermentation with W.anomalus LL-7 added 5 esters,5aldehydes,and 15 ketones,phenols,and pyrazines.W.anomalus LL-7 contributed significantly to the production of flavor substances,which was beneficial to the improvement of flavor richness of rice wine.The organic acid content of the combination fermentation with W.anomalus LL-7 decreased,and the organic acid content of the rice wine could be reduced by adding a certain proportion of W.anomalus to adjust the taste and aroma of the rice wine.