液化型淀粉酶和糖化酶是大曲最主要的淀粉水解酶系，其酶活力直接影响淀粉的转化率及出酒率。分析了大曲液化力和糖化力形成环境——大曲以及作用环境——酒醅中有机酸组成，发现均是乳酸含量远高于乙酸含量；考察酿酒过程中乙醇生成阶段的pH值、淀粉和乙醇变化曲线，结果发现，液化力和糖化力起作用的环境pH值在3．8左右；进而比较乙酸一乙酸钠和乳酸一乳酸钠两种缓冲液以及不同pH值对液化力及糖化力的影响。结果表明．相同条件下乳酸-乳酸钠缓冲液检测的大多数样品液化力和糖化力值偏高，说明其比乙酸一乙酸钠有利于发挥催化作用，而且不同样品的差距大，有利于对大曲样品质量区分和评价；而降低pH值检测酶活性能分析大曲酶制剂中耐酸性酶的组分更接近酿酒环境，有利于真实反映大曲酶系在酿酒过程起到的催化作用。%Liquefying amylase and saccharifying enzyme are the most important starch hydrolyzing enzymes in Daqu, and their activity may directly influence liquor quality and liquor yield. The formation environments of liquefying power and saccharifying power of Daqu, namely, the composition of organic acids in Daqu and in fermented grains was analyzed in this study. It was foundthat the content of lactic acids was far higher than that of acetic acid. Through the study of the change curves of pH, starch and ethanol concentration in ethanol formation stage in liquor-making process, it was found that pH value was about 3.8 during the stage. Furthermore, two kinds of buffer solution including sodium lactic acid buffer solution and sodium acetic acid buffer solution were compared and the effects of different pH value on the liquefying power and the saccharifying power of Daqu were investigated. The results suggested that under the same conditions, liquefying power and saccharifying power of Daqu samples were comparatively higher through sodium lactic acid buffer solution detection, indicating that lactic acid favored enzyme catalysis. Besides, the decrease of pH value in the detection of enzyme activity was good for truly reflecting the catalysis roles of Daqu enzymes in liquor-making process because the detection conditions were closer to real liquor-making environment.
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