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酱香白酒酿造过程放线菌的筛选与风味研究
【作者】 张建敏；
【作者基本信息】 贵州大学 ， 食品科学， 2015， 硕士
【摘要】 酱香型白酒酿造历史悠久,工艺独特,开放式的固态发酵造就了复杂而又特殊的酿酒微生态系统,最终形成酱香型白酒独一无二的酒体风格。酱香型白酒酿造体系微生态系统研究是科学认识酱香型白酒发酵中所蕴藏生物学问题的关键之一。放线菌作为酱酒酿造中的主要微生物之一,既有风味特征作用又有微生态功能作用。放线菌与产酱香功能细菌之间的微生态研究及风味影响机制分析,有利于深入研究酱香型白酒发酵机理,促进酱香型白酒进一步发展。本研究从产异味的放线菌出发,以探究白色链霉菌亚种(Streptomyces albus subsp.)(编号A22)与产酱香功能解淀粉芽孢杆菌(Bacillus amyloliquefaciens)(编号B6)发酵体系中风味影响机制为目的。通过对产异味放线菌的筛选及鉴定、酿造环境胁迫条件耐受性、特征代谢产物以及对产酱香功能细菌特征代谢风味成分影响等方面进行了研究,取得了如下的结果:(1)通过对酱香型白酒酿造过程中放线菌初筛得到30株,再通过固态发酵感官闻香,筛选到一株产异味突出的菌株(编号A22),经多相分类鉴定为白色链霉菌亚种(Streptomyces albus subsp.)。(2)对A22菌株进行主要酿造环境胁迫条件耐受性进行分析,结果表明:A22菌株能耐45℃高温、4%vol乙醇、pH4.0环境,其对主要酿造环境胁迫条件适应性较好。(3)通过HS-SPME和GC-MS对B6、A22、A22B6固态发酵代谢产特征性风味成分进行定性定量分析,结果表明:A22代谢所产土臭素是发酵醅中异味的主要来源,为关键特征性成分;功能细菌B6代谢所产吡嗪类物质是酱酒中的健康功能成分,高温有利吡嗪类总量和种类的增加;混菌发酵时,B6抑制A22产土臭素,发酵醅异味得到调节,风味得到改善,正常酿造条件调节减少酒醅异味;混菌发酵时,A22抑制B6产吡嗪类总量,从风味角度来说A22对B6吡嗪代谢具有一定的调节作用。(4)运用微生物计数方法对A22与B6混菌固态发酵的微生态生物学关系进行分析,结果表明:A22与B6存在明显的生物学关系。
【Abstract】 Maotai-flavor liquor brewing has a long history,unique technology,open fermentation to create a special and complex microbial systems, resulting in Maotai-flavor liquor wine with a unique style.Maotai-flavor liquor micro-ecosystem system is contained in the scientific understanding of Maotai-flavor liquor fermentation biology, one of the key issues.Actinomycetes as one of main microbes in Maotai-flavor liquor brewing, contribute to both liquor flavor characteristics and micro-ecological functions.The analysis of mechanism affecting the microecological research and the flavor between actinomycetes and Maotai-flavor-producing function bacteria is conducive to in-depth study of Maotai-flavor liquor fermentation mechanism to promote further development of Maotai-flavor liquor.This study starting mud-odor- actinomyces, explore the cultivating flavor impact mechanism of Streptomyces albus subsp.(A22) and Maotai-flavor-producing function Bacillus amyloliquefaciens(B6) for the purpose.This study start with screening and appraisal of mud-odor-producing actinomyces, brewing conditions of environmental stress tolerance,characteristics of metabolites and the effects on metabolism characteristic flavor of B6,Etc.The following results have been achieved:(1)This study screened 30 strains actinomycetes form the process of Maotai flavor liquor brewing.Through the flavor-oriented screening technology, one strains of off-odor substances producing actinomyces was isolated from them and identified as Streptomyces albus subsp.(A22).(2)Using the turbidimetric method for A22 strain’s brewing environment stress tolerance analysis, results showed that:the strain of A22 resistant to high temperature45 ℃, 4% vol ethanol, pH4.0; its brewing better environmental adaptability.(3)Qualitative and quantitative analysis of B6,A22, A22 in solid state fermentation metabolic characteristic flavor compounds by HS-SPME and GC-MS,and found: The strain of A22 producing geosmin is the main source of mud-odor;Functional bacterium B6 producing pyrazines are an important source of Maotai flavor.The high temperature of 55 ℃ is favorable to increasing pyrazine’samount and types;The strain of B6 had inhibition of A22 producing Geosmin in mixed culture and normal conditions had benefit to reduce the off flavor of liquor brewing.In mixed culture, A22 inhibited B6’s pyrazine flavor amount, from the perspective of flavor there is a apparent adjustment between the strain of B6 and A22.(4)Analysis of the use of microecological relationship, counting method of microorganisms on A22 and B6,the results showed that there is a apparent adjustment between the strain of B6 and A22.