以啤酒酵母FB作为出发菌株,通过紫外线诱变,并以发酵液中双乙酰含量为主要指标筛选获得一株优良啤酒酵母UB2。三角瓶低温发酵8d,其发酵液中双乙酰含量为0.088 5mg/L,比出发菌株FB降低38％;发酵液保持了亲株FB的优良风味和凝聚性,且部分发酵性能有了较大的改善;在500L发酵罐中试实验中,UB2菌株发酵过程中的双乙酰峰值为0.17mg/L,比FB降低了45％;双乙酰还原速度较快,比FB提前1d达到质量标准,结束主酵;发酵得到的酒液经品评认为口感优于亲株。With UV mutation and selection, four strains were obtained from Saccharomyces sp. FB,which was a strain for beer brewage production. The strains were investigated in 500 mL flask with 300 mL 12° Bx wort at 12℃. After 8-day fermentation, diacetyl content, flocculence, real degree of fermentation, al-coholicity, esters and higher alcohols content of the strains were measured. The results showed That the diacetyl content of these strains was reduced, than original strain. These strains possess other choiceness properties of FB contemporary. The diacetyl content in the fermented liquid of strain UB2 was 0. 088 5 mg/L,38% less than FB, which was 0. 138 9 mg/L. Strain UB2 got a scaling-up fermentation in a 500 L tank as further test while tracking diacetyl content change in the liquid, the data showed that the peak value of the diacetyl in the fermented liquid was 0. 17 mg/L, which was 45% lower that of original strain; and the final value of diacetyl of strain UB2 was less than 0. 08 mg/L at the 7th day, which was 1 day earlier than original strain. The beer produced with UB2 was appraised, the result indicated that it's better than the beer produced with FB
