| The soy sauce is a kind of traditional condiment with Chinese characteristics, and has a long history.Soy sauce industry in China gets behind with Japanese ones by a very long way, especially in the medium and minimum-scale enterprises. There are so many serious basic problems unresolved in such enterprises. For example, the low quality of koji, the long time of fermentation, the low utilization ratio of materials, the environmental and seasonal influence, and the unadvanced equipments, even manual operations, etc. These problems restricted the technical progress, also cumbered the increasing of economic benefit, and the improvement of product quality in the autochthonous soy sauce enterprises.The research contents and the conclusions can be summarized as following:(1) Determination methods of health index and physicochemical properties were established in draft soy sauce.(2) From results of 8 organic acids analyzed by HPLC, a comparison and count standard of organic acids detection in soy sauce was built. This mensuration has many excellences such as simple and effective for pretreatment, exact for determine result. This method also had the simple, rapid, well accuracy. Comparative research on type and content of Chinese soy sauce and Japanese soy sauce and found their difference in order to produce high quality soy sauce.(3) A detecting method of organic acids in fermentation liquid of halophilic yeast by HPLC was established. The Agilent ZORBAX SB-Aq column (150×4.6mm, 5μm) was used. Mobile phase was 0.02 mol/ L KH2PO4 (0.5 % acetonitrile, pH 2.0). The flow rate was 0.5 ml/ min, the temperature of column was 30℃and detected wavelength at 210 nm, 8 organic acids were separated commendably at the chromatographic condition. Consequently, good reproducibility and high sensitivity were achieved. The linear correlation coefficients were above 0.999. The method was used to analyze content of organic acids in fermentation liquid of the halophilic yeast. The diversification trend of oxalic acid, formic acid, malic acid, ascorbic acid, citric acid, cis-butenedioic acid and propionic acid in fermentation liquid was obtained.(4) Organic membrane and inorganic membrane were used in raw-soy sauce filtration. Effect of bacteria removing was discussed. 11 factors were compared before and after the filtration including flavor component, amino acid, organic acid, amino nitrogen and total nitrogen. The results showed that not only the bacteria removing rate of organic membrane was much better than that of inorganic membrane, but the organic membrane had advantages over inorganic membrane and heat sterilization concerning other 11 factors as well. Therefore, the 0.1μm pore diameter organic membrane was made of poly vinylidene fluoride (PVDF) and the operation condition was: pressure 1MPa, 31-33℃and so on. The inorganic membrane was made of ceramics and the operation condition was: pressure 1.3MPa, 31-33℃and so on. A delicious soy sauce was produced without any significant changes in physical-chemical parameters and flavor after being filtrated with a filtration device.(5) Organic membrane and inorganic membrane were used in raw-soy sauce filtration to obtain draft soy sauce. Solid phase micro-extraction (SPME) and GC-MS were applied to analyse the flavor compounds of two types of draft soy sauce. Totally 70 compounds were identified from two samples. These compounds included alcohols(18), phenols(5), esters(7), aldehydes(13), ketones(5), acids(2), heterocyclics(8) and hydrocarbon(6). The main flavor compounds were alcohols, phenols, aldehydes, ketones heterocyclic. The results of the study provided evidence for the improvement and enhancement of the traditional fermentation of soy sauce.
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