四川麸醋发酵过程中醋醅理化指标及有机酸变化分析

Analysis of physicochemical indexes and organic acid changes of Cupei during Sichuan bran vinegar fermentation process

以四川麸醋醋醅为研究对象,利用国标方法和高效液相色谱(HPLC)技术分别对不同发酵时期醋醅的理化指标及有机酸含量的变化进行分析。结果表明,不同发酵时期醋醅的理化指标具有较大的差异。醋醅中水分含量呈先升后降的趋势,在发酵3 d时最高(63.90%);p H值缓慢降低,但始终维持在4.0~4.4之间,总酸含量呈增长趋势,两者之间呈负相关;挥发酸、不挥发酸与总酸变化趋势大致相同;氨基酸态氮含量呈先快后慢的上升趋势;还原糖含量先升高后降低,发酵9 d时含量最高(10.13 g/100 g干醅),淀粉含量则呈下降趋势。从醋醅样品中共检测出8种有机酸,分别为草酸、酒石酸、丙酮酸、苹果酸、乳酸、乙酸、柠檬酸、琥珀酸,随着发酵的进行均呈增长趋势,其中乙酸和乳酸为主体有机酸。

Taking Sichuan bran vinegar grains as the research object, the changes of physicochemical indexes and organic acid content in fermented vinegar grains at different fermentation periods were analyzed by national standard method and HPLC, it was found that the physicochemical indexes were quite different. The water content of fermented vinegar grains showed a trend of rising first and then falling with the fermentation, and the content was the highest on the third day of fermentation. The p H value decreased slowly, but maintained between 4.0-4.4, while the total acid content was in an increasing trend, showing a negative correlation between the two. The change trend of volatile acid and non-volatile acid was similar to that of total acid,the ammonia nitrogen content showed a trend of gradual increase, and the increase was fast in the early stage of fermentation, and relatively slow in the late stage. Reducing sugar content first increased and then decreased, and the content was the highest(10.13 g/100 g dry mass), while the starch content showed a downward trend. Eight kinds of organic acids were detected, including oxalic acid, tartaric acid, pyruvic acid, malic acid, lactic acid, acetic acid, citric acid and succinic acid. The contents of these organic acids increased with the development of fermentation, and the main organic acids were acetic acid and lactic acid.