浓香型大曲培菌期主要微生物变化及挥发性风味物质合成影响因素研究

Influencing Factors of Changes of Main Microorganisms and Synthesis of Volatile Flavor Substances During the Culture Period of Nongxiang Daqu

分析浓香型大曲培菌期温度、湿度、水分等对主要微生物生长的影响,研究挥发性风味物质合成与微生物的相关性。制曲过程中发酵温度、湿度、水分等会影响微生物的生长代谢,利用可培养的方法对不同发酵条件下酵母菌、醋酸菌、乳酸菌、霉菌以及芽孢杆菌进行计数以了解其变化规律,利用Spearman相关性分析了解大曲主要微生物与理化因子的相关性;通过固相微萃取-气相色谱-质谱联用技术(SPME-GC-MS)对制曲过程产生的挥发性风味物质进行测定,运用共现网络构建挥发性风味网络,基于皮尔逊相关系数分析浓香型大曲培菌期发酵过程中主要微生物变化与挥发性风味物质合成的相关性。研究表明:制曲过程中酵母菌、醋酸菌、乳酸菌、芽孢杆菌的数量均呈现先上升后下降的趋势,霉菌的数量整体上升;浓香型大曲培菌期醋酸菌与温度呈负相关(p<0.05),与湿度呈正相关(p<0.05);乳酸菌与温度呈负相关(p<0.05),与湿度和水分呈正相关(p<0.05);酵母菌与湿度、水分呈正相关(p<0.05);霉菌与温度呈正相关(p<0.05),与湿度呈负相关(p<0.05)。挥发性风味物质主要以醇类、酸类、醛类和酯类为主,同时还产生呋喃类、吡嗪类物质,风味物质之间几乎是以协同的方式相互作用,具有一定的伴随关系。霉菌与酸类物质以及酯类物质的合成具有显著的正相关性,与醛类物质的合成具有显著的负相关性;酵母菌、醋酸菌和乳酸菌与酯类物质的合成具有显著的正相关性。

The effect of temperature,humidity and moisture on the growth of main microorganisms during the culture period of Nongxiang Daqu was analyzed,and the correlation between the synthesis of volatile flavor substances and microorganisms was studied.Cultivable method was used to count the numbers of yeasts,acetic acid bacteria,lactic acid bacteria,molds and bacillus under different fermentation conditions to understand their change rules.Spearman correlation was used to analyze the correlation between the main microorganisms and the physicochemical factors of the Daqu.The volatile flavor substances were determined by SPME-GC-MS,the volatile flavor network was constructed by co-occurrence network,and the correlation between the changes of main microorganisms and the synthesis of volatile flavor substances was analyzed based on Pearson correlation coefficient.The results showed that the numbers of yeasts,acetic acid bacteria,lactic acid bacteria and bacillus increased first and then decreased during the culture period of Nongixang Daqu,while the number of molds showed an overall increase.The acetic acid bacteria were negatively correlated with temperature(P<0.05),and positively correlated with humidity(P<0.05);the lactic acid bacteria were negatively correlated with temperature(P<0.05),and positively correlated with humidity and moisture(P<0.05);the yeasts were positively correlated with humidity and moisture(P<0.05);the molds were positively correlated with temperature(P<0.05),and negatively correlated with humidity(P<0.05).The volatile flavor substances were mainly alcohols,acids,aldehydes and esters;furans and pyrazines were also produced.The flavor substances had a synergistic effect.The molds had a significantly positive correlation with the synthesis of acids and esters,and a significantly negative correlation with the synthesis of aldehydes;the yeasts,acetic acid bacteria and lactic acid bacteria had a significantly positive correlation with the synthesis of esters.