Construction of the Fine Brewer's Yeast Strains DR9-2 by Fusion of Two Inactivated Parents' Protoplast and Study of its Fermentation Characters

啤酒酵母菌株JW1-1发酵液中的双乙酰、总高级醇的含量较低,但发酵度较低,发酵液中的乙醛含量较高;啤酒酵母菌株NW7-45发酵度较高,发酵液中的乙醛含量较低,但发酵液中的双乙酰、总高级醇的含量较高。为了得到优良的菌株,以紫外线灭活的菌株JW1-1原生质体和热灭活的菌株NW7-45原生质体为亲本进行融合。经三角瓶发酵筛选,得到较优良的融合株DR9-2和DR9-24。其中融合株DR9-2以12°Bx麦芽汁为培养基,用500L的发酵罐在12℃下发酵,发酵11d发酵液的发酵度为69.5%,发酵液中的双乙酰、乙醛和总高级醇的含量分别为0.0124mg/L、7.70mg/L和61.88mg/L。从融合株DR9-2的主要发酵特性和啤酒口感品评的结果表明,该菌株在啤酒酿造工业中具有应用前景。Sacchararomyces cerevisiae JW1-1 was a strain with the relatively low content of diacetyl and total higher alcohols but relatively high content of acetaldehyde in the fermented liquid and relatively low fermented degree, while Sacchararomyces cerevisiae NW7-45 was a strain with relatively high fermented degree and relatively low content of acetaldehyde but relatively high content of diacetyl and total higher alcohols in the fermented liquid. .In order to construct the fine brewer's yeast strains, the fusion of UV-inactivated strain JW1-1 protoplast and heat-inactivated strain NW7-45 protoplast was carried out. The fine fusants DR9-2 was obtained after selecting by flask fermentation. The content of diacetyl, acetaldehyde, total high alcohols of DR9-2 in the fermented liquid were 0.0124mg/L,7.70mg/L and 61.88mg/L, respectively, and the fermentation degree was 69.5% in 500L fermentor using 12°Bx wort as the medium at 12℃ for 11 days. The main fermentative property and the sensory evaluation of the beer of DR9-2 indicated that strain DR9-2 is of well applied prospect on the beer brewing