Objective:The production process of esterified Monascus bran koji was optimized,and its effect on Luzhou-flavor liquor was explored.Methods:Five strains of Monascus were screened from Daqu,and the esterifying enzyme production ability of the strains was detected by the ester decomposition method.The strain with the most prominent enzyme production ability was selected to prepare Monascus bran koji.The koji-making process was optimized by single factor and orthogonal experiments and applied to liquor production.Results:Among the five strains,the J-3 strain had the strongest ability to produce esterification enzyme.Under the conditions of 50％moisture,4％inoculation amount,pH 4.0 and 32 ℃ culture temperature,the esterification enzyme activity was as high as 77.78 mg/g bran koji.The bran koji was added to the fermented grains according to different inoculation amounts.Compared with the fermented grains without bran koji,when the inoculation amount of bran koji was 1％,the content of ethyl acetate in the fermented grains increased by 4.84 times,and the content of ethyl caproate increased by 3.55 times.When the inoculation amount was 1.5％,the content of ethyl butyrate increased by 4.72 times.The addition of esterified Monascus bran koji can improve the utilization rate of alcohol and starch,and significantly increase the total ester content in fermented grains.Conclusion:Adding Monascus bran koji to fermented grains according to the appropriate inoculation amount can improve the quality of Luzhou-flavor liquor.

为探索窖泥中放线菌在窖池中的性能,本研究以浓香型白酒窖泥为菌源,采用梯度稀释平板法从中分离出两株放线菌菌株,对目标菌株进行多相分类鉴定,包括16S rRNA基因序列分析、形态观察及部分生理代谢特性分析.本研究通过筛选培养获得两株放线菌菌株(X,Z)后的初步鉴定结果为:菌株X和菌株Z分别为产灰链霉菌(Streptomyces griseus)以及德氏链霉菌(Streptomyces drozdowiczii).通过分析实验结论得知,两株菌最适生长pH值为6.5,最适生长温度区间均在25～30℃;菌株X可耐受乙醇浓度为10％,菌株Z可耐受乙醇浓度为8％;菌株X在液态环境下的对数生长期为12～48 h,菌株Z在液态环境下的对数生长期为18～48 h,两菌株稳定期均在48 h后;通过测试发现两株放线菌均能产生淀粉酶,且菌株X产淀粉酶能力明显强于菌株Z,结果表明窖泥中的放线菌株拥有分解淀粉的能力,可以为其他需葡萄糖微生物提供必要的营养物质;菌X和菌Z均无产抗生素能力或产抗生素能力极低,表明在窖泥环境中,放线菌可能无需产生抗生素也能和其他微生物共生长.

以高粱糖化液模拟发酵体系,添加0～30mmol/100g的乳酸以设置不同的初始发酵酸度,通过考察酿酒酵母(Saccharomyces cerevisiae)的生物量、发酵累计质量损失、发酵液乙醇生成、发酵液关键香气物质,探究不同初始酸度对酿酒酵母发酵状况的影响,以期解析初始酸度对白酒发酵产酒的影响.结果表明,随初始发酵酸度增加,酿酒酵母生长受到抑制,低初始酸度条件下(0～15 mmol/100g)有利于酿酒酵母发酵,加快CO2释放和糖代谢速率及更多种类挥发性风味物质生成,当初始酸度为15 mmol/100g时,醇类、酸类及总挥发性物质种类数最高;较高的初始酸度(15～30 mmol/l00g)会抑制酿酒酵母乙醇的生成.6种关键性挥发性风味物质检测结果表明,初始酸度为5 mmol/100g时,酿酒酵母发酵末期的关键风味物质乳酸乙酯、苯乙醇、异丁醇和异戊醇含量达到最高,20mmol/100g的初始酸度更有利于乙酸乙酯生成,乙酸苯乙酯的生成随初始酸度增加而被抑制.综上,控制初始酸度为15 mmol/100 g左右发酵效果较好.

为探究五粮浓香型白酒发酵过程中黄水的理化指标及风味物质的变化规律,该研究通过对五粮浓香型白酒酒醅发酵过程中的黄水进行连续采样,检测黄水理化指标,结合顶空固相微萃取-气相色谱-质谱联用仪(HS-SPME-GC-MS)以及高效液相色谱(HPLC)分析黄水中的风味物质,比较不同天数的黄水理化指标和风味物质差异.结果表明,黄水pH值在整个发酵周期稳定在3.35～3.50;酸度在35 d达到最大值57.77 mmol/100 mL;淀粉和还原糖含量整体呈现下降趋势;酒精度在28 d达到最大值3.41％vol;固形物含量波动较大,与淀粉和还原糖含量变化存在一定关系;正交偏最小二乘法判别分析结果表明:不同发酵时期的黄水风味物质存在较大差异,变异权重参数值大于1的风味物质有11个,主要为酯类和酸类,其中乳酸乙酯及己酸乙酯大量产生于7～35 d,乙酸乙酯、丁酸乙酯在42～70 d大量积累.该研究获得了浓香型白酒发酵过程黄水物质变化规律,为后期选择黄水作为介质监控发酵过程提供了一定参考价值.

[目的]分离鉴定古盐井中的嗜盐菌,确定相容性溶质,增加相容性溶质的合成.[方法]从盐井卤水中分离嗜盐菌,对菌株进行形态、生理生化和16S rRNA分析,用高效液相色谱法(HPLC)和质谱法(MS)确定相容性溶质,以谷氨酸钠为唯一碳氮源来制备四氢嘧啶.[结果]菌株S2为色盐杆菌属;相容性溶质为四氢嘧啶;1.5 mol/L NaCl时四氢嘧啶达到最适合成浓度,为0.168 3 mg/mL,单位质量合成量为238.201 mg/g;以谷氨酸钠为唯一碳氮源时,相同体积发酵液中四氢嘧啶的总合成量与单位质量合成量均增加,四氢嘧啶合成量为0.184 8 mg/mL,单位质量合成量为390.389 mg/g.[结论]成功分离出了产四氢嘧啶的嗜盐菌,并且以谷氨酸钠为唯一碳氮源时四氢嘧啶合成量大大增加.