The Variation Of The Flavor Substances In Aerobic Solid-fermentation Cultures Of Hengshun Vinegar

Vinegar production, as an important part of the Chinese ancient, has a long history in China. As a sour condiment, the flavor of vinegar is asked full-bodied and harmonious. Zhenjiang Hengshun vinegar is one of the famous vinegars, producing by solid-state delaminating fermentation. The flavour of Hengshun vinegar is sour and not astringent, fragrant and slightly sweet, moreover, the longer keeping, the more fragrant. The success of the open solid-state fermentation depended on the conjunct fermentation by various microbes from environment. The changes of microbes during fermentation are complex, so that the flavor substances form and change complexly. In this thesis, we examined the flavour substances of vinegar cultures by head space-solid phase microextraction-gas chromatogragh -mass spectrum (HS-SPME-GC-MS) and high performance liquid chromatography (HPLC), clustered by Matlab 7.0, to analyse the changes of flavor substances of vinegar cultures. The main results were as following:The changes of some physicochemical indexes were detected continuously. In general, the titratable acidity, dissoluble saltless substance, formaldehyde nitrogen increased throughout the fermentation period, while pH, changing wthin 3.6~3.9, decreased firstly, then leveled off, and increased finally. Unvolatile acid increased firstly, and then decreasted. Content of water and temperature in super, middle and under layers were different. Volatile acid produced mainly in super layer. Unvolatile acid produced mainly in under layer, Especially in the under layer of the former eight days, and then declined a little.The HPLC analysis results indicated that acetic acid, lactic acid were two important organic acids, accounting for more than 75% organic acids of the vinegar culture. The original culture contained 430.4 mg lactic acid per 100 gram culture, five times more than acetic acid. Lactic acid increased quickly during the form days, and decreased gradually during the latter days. Acetic acid increased quickly during the form days too, and increased slowly during the latter days. The tartaric acid was the third content of organic acid. Succinic acid, pyruvic acid and organic acid had large fluctuations; whereas tartaric acid , oxalic acid, citric acid and fumaric acid did not change significantly; Surprisingly, the content of malic acid showed a downward trend along with the process of acetic acid fermentation.The contents of alanine, leucine, praline, valine, glutaminc acid,γ-amidobutyric acid, were wthin 50~150mg per 100 gram culture. The six kinds amino acids accounted for 72 percent of total dissociative amino acid. The conetents of tyrosine, serine, aspartic acid, lysine, cysteine were low. Alanine, leucine, praline, valine, glutaminc acid, andγ-amidobutyric acid increased quickly, at about the average day growth rate of 10 percentents. Cysteine ,aspartic acid, aspartic acid, phenylalanine grew slowly.Detecting volatile compounds in the vinegar cultures by HS-SPME-GC-MS and clustering by Matlab 7.0, we can knew somethings about changes of volatile compounds. Ethyl acetate, ethyl lactate were the two abundance esters. Acids and alcohols could contact adequately by the solid-state delaminating fermentation, especialy during the prophase fermentation, therefore, esters increased quickly during the prophase fermentation. Ethanol increased in bottom cultures during the prophase of fermentation, and then declined quickly. Benzeneethanol was the important flavour compound. 2,3-butylene glycol, 2,3-Buranedione, acetoin were the important flavour compounds. Tetramethyl pyrazine started forming during the anaphase of the fermentation.