米酒生香酵母的分离筛选鉴定及其性能研究

为获得米酒酿造中优良的生香酵母,通过嗅闻法初筛得到6株香气突出的菌株,通过测定菌株发酵米酒过程中乙酸乙酯、β-苯乙醇、乳酸乙酯和乙醇的积累量,复筛获得菌株11Z1,其积累量分别为(2.883±0.260)、(0.301±0.028)、(0.080±0.008)和(37.296±1.036)g/L。经形态学及分子生物学方法鉴定菌株11Z1为Cyberlindnera fabianii;对其发酵液进行风味物质分析,检测出主要风味物质共21种,包括醇类5种、酯类3种、酸类5种、酚类1种、酮类1种、烷烃类2种和其他类4种,这些风味物质对增加酒的香气及形成酒体风格具有积极作用。此外,分别在培养基中添加风味前体物乙酸、L-苯丙氨酸和L-乳酸,进一步探究其对菌株11Z1酿造米酒风味物质形成的影响,结果表明,添加体积分数0.3%乙酸发酵9 d、8 g/L L-苯丙氨酸发酵4 d、体积分数0.4%L-乳酸发酵8 d,乙酸乙酯、β-苯乙醇及乳酸乙酯积累量分别达到最大,与未添加前体物相比分别提高了160.71%、215.48%和144.04%。综上,菌株11Z1具有突出的生香能力,展现出在米酒酿造中巨大的应用潜力。

Isolation,identification and characteristics of aroma-producing yeast for rice wine

In order to obtain aroma-producing yeast strains with excellent performance in rice wine brewing,olfactory method was used to screen strains with aroma from 11 samples,and the accumulations of ethyl acetate,β-phenylethanol,ethyl lactate and ethanol were determined to rescreen strains with outstanding aroma-producing ability.The results indicated that among the 6 strains obtained by primary screening,strain 11Z1 exhibited outstanding aroma-producing ability.The accumulations of ethyl acetate,β-phenylethanol,ethyl lactate and ethanol of strain 11Z1 were(2.883±0.260),(0.301±0.028),(0.080±0.008)and(37.296±1.036)g/L,respectively.According to morphological and phylogenetic analysis,strain 11Z1 was identified as Cyberlindera fabianii.Moreover,the flavor compounds of strain 11Z1 were analyzed,and 21 kinds of main flavor compounds were detected,including 5 alcohols,3 esters,5 acids,1 phenol,1 ketone,2 alkanes and 4 other compounds.These flavoring substances have a positive effect on increasing the aroma of wine and forming wine body style.Besides,the effects of adding precursor substances of flavor substances in culture medium such as acetic acid,L-phenylalanine and L-lactic acid on the formation of flavor compounds of strain 11Z1 were further studied.The results indicated that the accumulations of ethyl acetate,β-phenethyl alcohol and ethyl lactate reached the maximum after fermentation with 0.3%(volume fraction)acetic acid for 9 d,8 g/L L-phenylalanine for 4 d,and 0.4%(volume fraction)L-lactic acid for 8 d,which have increased by 160.71%,215.48%and 144.04%,respectively,compared with that without adding precursor substances.In summary,strain 11Z1 has outstanding aroma-producing ability,which shows great application potential in rice wine brewing.