产香酵母Pichia myanmarensis LX15的分离纯化及对精酿啤酒风味物质形成的影响

为了适应精酿啤酒对个性化风味的需求,能产生特定风味化合物的产香酵母成为研究者的研究重点。从精酿啤酒原液中分离到1株产香酵母LX15菌,该菌细胞呈圆形或卵圆形、多极芽殖生长;LX15菌在玉米粉培养基上培养7~10 d不形成假菌丝,在酵母膏蛋白胨培养基上培养3 d能够形成子囊孢子。经生理生化特征和系统发育分析,确认该生香酵母为Pichia myanmarensis菌中的一个菌株,所产主要风味化合物包括乙酸乙酯、乙酸异戊酯、己酸乙酯和辛酸乙酯。当LX15菌与啤酒酵母C1菌共发酵时,能够产生协同效应,提高酯类化合物和高级醇类的含量,并与LX15菌的接种比例正相关,但并不影响啤酒酿造的整体发酵速率和发酵能力。因此,LX15菌是一株适于提高精酿啤酒风味的产香酵母菌。

Isolation and Properties of Aroma Producing Pichia myanmarensis and the Effects of the Formation of Aromatic Substances in Craft Brewed Beer

In order to meet the demand of individualized flavors in craft brewed beer, more attentions have been focused on the yeast producing specific aroma compounds. In this paper, one aroma producing yeast strain was isolated from the crude craft brewed beer, LX15. The strain cells are spherical to ovoid and multipolar budding. Pseudohyphae were not formed after LX15 was cultured on cornmeal media for 7~10 days, and ascospores could formed on yeast extract peptone media cultured for 3 days. Phenotypic and phylogenetic analyses suggested that LX15 was confirmed to be a strain of Pichia myanmrensis, and the flavors compounds it produced included ethyl acetate, isoamyl acetate, ethyl hexanoate, ethyl octanoate. When strain LX15 was fermented with beer yeast C1 together, the synergistic effect could produced to increase the content of esters compound and high grade alcohols, which is positively related with inoculation volume ratio between LX15 and strain C1, however, no effect on the whole beer brewing and fermentation capability. Therefore, LX15 is an aroma-producing strain suitable for increasing the flavor for the craft-brewed beer.