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Vinegar has a long history and is an important part of our culture. As a daily acidic condiment, vinegar flavor full and coordination is very important. Sichuan bran vinegar is a traditional four famous vinegar is one of the traditional solid-state fermentation using microorganisms from the environment to participate in a variety of fermentation. Because changes in bacteria during fermentation complex flavor compounds formation and change is also quite complex. In this study, using high performance liquid chromatography, solid phase micro-extraction and GC-MS analysis techniques such as Sichuan bran vinegar vinegar mash fermentation process tracking detect, analyze the variation of its flavor. The results are as follows: 1, Sichuan bran vinegar fermentation and aging process of physical and chemical indicators of change research in Sichuan bran vinegar fermentation and aging process, the total acid, non-volatile acids, amino nitrogen, soluble solids without salt, sugar, etc. were tracking and detection analysis, the results showed that the fermentation period, with the fermentation time, total acid, amino acid nitrogen and soluble solids content were increased without salt, sugar content decreased, the color is slightly deepened. Aging period in total acid, amino nitrogen and reducing sugars decreased slightly, slightly soluble salt solids began to increase, when aging time is too long, however, reduced. Non-volatile acid content increased rapidly during the fermentation early, late and aging period reduced. pH of the fermentation and aging process in addition to nine days before the decline, the rest are relatively stable. Two years later aged vinegar color becomes dark brown. 2, Sichuan bran vinegar fermentation and aging process changes of organic acids and lactic acid content of Sichuan bran vinegar two highest organic acids. Content of acetic acid in the fermentation of grains from 103.99mg/100g vinegar rose to 3593.34 mg/100g, 7 days before growth was particularly fast; aging process in a slight decrease in acetic acid, 48-month fell to 3362.08 mg/100g vinegar grains. Higher than the pre-fermentation lactic acid acetic acid, lactic acid levels rise before seven days to a maximum of 2146.44 mg/100g vinegar grains, then began to gradually reduce the aging June 856.09 mg/100g vinegar grains, after content decreased slightly, but only slightly . Tartaric acid content increased and then decreased, but the magnitude of increase and decrease is not large. Pyruvate levels rise during the fermentation period, little change into the aging stage. Citric acid and malic acid content during fermentation and aging process of a downward trend, oxalic acid content changed little. 3, Sichuan bran vinegar fermentation and aging process of changes in the composition of the volatile solid phase micro-extraction and GC-MS for vinegar fermentation and aging of the volatile components were detected grains obtained the volatile flavor compounds were studied. Sichuan bran vinegar volatile components and the total number of species in the fermentation period peak area increased rapidly to reach the maximum pre-aging, then began to decline. With the change, the type and content of volatile components have undergone significant changes, a large number of esters and alcohols reduced or even disappear, but also a new generation of volatile components, such as some aldehydes, ketones, heterocyclic and long carbon chain acids. The type and quantity of esters are reduced during fermentation and aging. The content of ethanol in the fermentation and aging period of steady decline, phenethyl alcohol fermentation was carried out with increasing content and aging one month maximum. Fewer types of acid fermentation, aging after a long carbon chain acid content increased. With a large number of fermentation acid production, Rule 15d starts remain stable and in aging three years declined slightly. In addition, many aldehydes, ketones and heterocyclic compounds are produced by aging period, in particular the content of pyrazines aging was significantly increased.
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