清香型白酒大曲中产酶产香霉菌的筛选、鉴定及耐受性研究

Screening,identification and tolerance of enzyme and aroma-producing mold from light-flavor Baijiu Daqu

该研究采用传统培养分离技术结合形态学观察从清香型白酒大曲中分离霉菌,并通过糖化力、液化力、酯化力、脂肪酶活及产香能力分析从中筛选产酶及产香性能优良的霉菌。通过分子生物学技术对筛选菌株进行鉴定,并对其耐高温、耐pH、耐乙醇能力进行分析。结果表明,从清香型大曲中共分离出6株霉菌,从中筛选得到1株产酶及产香性能优良的霉菌,编号为MJ-5,该菌株在麸皮培养基中30℃培养3 d后,糖化力为258.02 U/g、液化力0.42 U/g、酯化力为44.51 U/g、脂肪酶活力为8.98 U/g;菌株MJ-5麸曲中的苯乙酸乙酯(15.7%)、月桂酸乙酯(1.74%)相对含量较高,有助于增加白酒果香,此外还检测到了(-)-alpha-古芸烯(0.96%)。经鉴定,菌株MJ-5为分支横梗霉(Lichtheimia ramosa),其具有较好的耐受性,可耐受高温39℃、pH值4、乙醇体积分数6%的生长环境。

The molds were isolated from light-flavor(Qingxiangxing)Baijiu Daqu by traditional culture and separation technology combined with morphological observation,and the molds with superior enzyme and aroma production performance were screened by analyzing the saccharification power,liquefaction power,esterification power,lipase activity and aroma production ability.The selected strain was identified by molecular biological techniques,and their tolerance to high temperature,pH and ethanol were analyzed.The results showed that a total of 6 strains of mold were isolated from light-flavor Daqu,and one strain named as MJ-5 with superior enzyme and aroma production performance was screened.The strain MJ-5 was cultured in bran medium at 30℃for 3 d,the saccharification power was 258.02 U/g,the liquefaction power was 0.42 U/g,the esterification power was 44.51 U/g,and the lipase activity was 8.98 U/g.The relative contents of ethyl phenylacetate(15.7%)and ethyl laurate(1.74%)in the Fuqu fermented with strain MJ-5 were higher,which helped to increase the fruit flavor of Baijiu.In addition,the(-)-alpha-guassene(0.96%)was also detected.The strain MJ-5 was identified as Lichtheimia ramosa,which had good tolerance and could tolerance high temperature 39℃,pH 4 and ethanol volume fraction 6%.