甜酒曲中优质酵母菌的分离鉴定及其产香特性分析

为提高传统米酒的香气品质、实现其标准化生产，对从中国几种地方特色甜酒曲中分离筛选出的具有优良发酵和产香特性的酵母菌株进行26S rDNA序列分析及系统发育树构建，并分析了其发酵米曲汁的香气成分及特征。结果表明：所筛选的6 株酵母菌中，CMY001、CMY003和NBY003为酿酒酵母（Saccharomyces cerevisiae），CMY002和NBY002为异常威克汉姆酵母（Wickerhamomyces anomalus），YCY001为光滑假丝酵母（Candida glabrata）。乙醇体积分数小于10%时YCY001耐受性较好，大于10%时CMY002耐受性较好；NBY002对温度耐受性良好；各菌株在pH 3～11条件下均能生长；发酵能力最强的是NBY003，菌株NBY002的产酯量最高，为5.125 g/L。在米曲汁培养基中，NBY002产β-苯乙醇能力明显高于其他菌株，发酵产物呈现较强的花香味；YCY001发酵产物中酯类的多样性及相对含量显著高于其他菌株，具有较丰富的酯香味；CMY001发酵产物具有脂肪香、酒香和草香特征，CMY002和CMY003的发酵产物果香浓郁；6 种酵母菌发酵产物的整体香气有明显差异，其中丙烯酸辛酯、乙酸苯乙酯、乙酸乙酯、甲酸异戊酯、β-苯乙醇、辛酸和苯甲酸乙酯是不同酵母发酵产物呈现不同香气特征的关键物质。

Fermentation Characteristics for Flavor Compounds Production by Quality Yeast Strains Isolated from Rice Wine Starters

In order to improve the aroma quality of traditional rice wine and to realize its standardized production, six yeaststrains with excellent fermentation characteristics for aroma production were isolated from several local characteristicrice wine starters in China and were identified by 26S rDNA sequence analysis. A phylogenetic tree was constructed forthe strains, and the aroma characteristics of rice koji juice fermented with each of the strains separately were analyzed.The results showed that strains CMY001, CMY003 and NBY003 were identified as Saccharomyces cerevisiae, CMY002and NBY002 as Wickerhamomyces anomalus and YCY001 as Candida glabrata. YCY001 was well tolerant to alcoholcontents lower than 10%, while CMY002 could tolerate alcohol contents higher than 10%. NBY002 was well tolerant totemperature. All the strains could grow at pH 3–11;NBY003 had the strongest fermentation ability, and NBY002 exhibitedthe highest ester production up to 5.125 g/L. In the rice koji medium, the β-phenylethanol producing ability of NBY002was significantly higher than that of the other strains, producing a strong floral aroma. The diversity and relative content ofesters produced by YCY001 were significantly higher than those produced by the other strains, giving a rich ester aroma.CMY001 produced fatty, wine-like and grass-like aromas, while CMY002 and CMY003 gave a strong fruity aroma. Ingeneral, significant differences were found among the aroma profiles produced by the six strains. Octyl acrylate, phenylethylacetate, ethyl acetate, isoamyl formate, β-phenylethanol, caprylic acid and ethyl benzoate were the key aroma compoundscontributing to the discrimination of the fermentation products of the six strains.