Comparative Study On Flavor Components Of Zhenjiang Aromatic Vinegars Produced By Traditional Manual And Modern Industrial Technology

Zhenjiang aromatic vinegar(ZAV) is Chinese typical fermentative food, which is famous for its color, aroma, acid, mellowness and denseness. With the development of modern science and technology, the processing method of ZAV has been optimized and improved. The difference between traditional craft and modern technology mainly lies in the alcoholic fermentation, in which the former was mixed with wheat koji for multi-strain fermentation artificially, while the latter was added glucoamylase,amylase and saccharomyces cerevisiae for pure fermentation mechanically, and the products were called traditional manual vinegars(TMVs) and industrial vinegars(IVs), respectively. The different processing methods may have a great influence on the flavor components in TMV and IV. This work analysed the flavor components in TMVs and IVs aged for different years and produced in different seasons. It can provide a powerful basis for the production of better flavor and more nutritious ZAV. The main contents of this paper were summarized as follows:1. This work analysed the contents of reducing sugars, total acids, amino acid nitrogens, organic acids and free amino acids in TMVs and IVs through 3,5-dinitrosalicylic acid colorimetry(DNS), direct titration, high performance liquid chromatography(HPLC) and automatic amino acid analysis method, respectively. The results showed that the contents of total acids, amino acid nitrogens, organic acids and free amino acids in TMVs were much higher than that in IVs at the same age and produced in the same season, however, the contents of reducing sugars in TMVs were lower than that in IVs.2. The contents of volatile compounds in TMVs and IVs were analyzed by head space-solid phase microextraction coupled with gas chromatography-mass spectrometry(HS-SPME/GC-MS). The results showed that the contents of volatile compounds in the new IV and IVs aged for half a year, two years, four years and produced in four seasons were higher than that in TMVs at the same age and produced in the same season.3. The results of gas chromatography-olfactometry(GC-O) showed that the aroma of IVs was full-bodied and the aroma of TMVs was soft. The difference in aroma between TMVs and IVs mainly lay in the aroma intensity of acids, alcohols, esters and heterocyclic compounds.The production seasons almost had no influence on the aroma intensity of alcohols, ketones and other compounds in TMVs and IVs.4. Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry(GC×GC-TOFMS) was used to study the volatile components in ZAVs. A total of 667 components were identified in TMVs and IVs by GC×GC-TOFMS, including 111 esters, 90 alcohols, 52 aldehydes, 60 acids, 121 ketones, 84 heterocyclic compounds, 21 phenolics, 48 hydrocarbons, 23 nitrogenous compounds, 9 sulphur compounds and 48 other compounds. The results fully reflected the complexity and diversity of volatile components in ZAVs. The numbers of volatile components in the new IV and IVs aged for two years, four years and produced in four seasons were more than that in TMVs at the same age and produced in the same season.The results of this study can guide the optimization of production technology of ZAV, in oder to improve production efficiency, while giving full play to the potential advantages of traditional food.