The Preliminary Quantitative Discovery Of Parameters In Soy Sauce Fermentation

Soy sauce fermentation processes are now divided into two categories including low-salt solid-state fermentation as well as high-salt diluted-state fermentation. At present, different manufacturers of soy sauce have different processing parameters such as the fermentation temperature, salinity and production cycle, leading to various products. If mathematical models are able to establish to describe the relationship between physicochemical indexes of soy sauce and the fermentation conditions, it will be of great meaning to guide the production.This paper mainly studied the rules of physicochemical indexes changing with time under the conditions of low-salt solid-state and high-salt diluted-state fermentation. Based on that, it made a preliminary discovery of fitting curves to explain the relationship between physicochemical indexes (such as ammoniacal nitrogen etc.) at the end of fermentation and fermentation temperature, as well as salinity. By using HS-SPME-GC/MS, it also studied the rules of flavor substance content changing with time in the process of multi-strain high-salt diluted-state fermentation which helped to determine the best fermentation period. The main conclusions are as following:1. By studying the fermentation process of low-salt solid-state soy sauce under39°Be,42°Be,45°Be and48°Be, fitting curves were got to describe physicochemical index like ammoniacal nitrogen content changing with time respectively. Using Origin software to fit the relationships between the ammoniacal nitrogen content and fermentation temperature on25d, the resulting fitting curve is y=1.2077-0.00337x+1.66667E-4x2. After analysis of variance, the fitting curves above have a good fitting degree with small error which can precisely reflect the relationship between physiochemical indicator and fermentation temperature. In the range of39-48°Be, the ammoniacal nitrogen content of soy sauce on25d goes up as the temperature increases.2. By studying the fermentation process of high-salt diluted-state soy sauce in brine with concentration of15°Be,17°Be,19°Be,21°Be and23°Be, fitting curves were got to describe physicochemical indexs like ammoniacal nitrogen content changing with time respectively. Using Origin software to fit the relationships between the ammoniacal nitrogen content and salinity on56d, the resulting fitting curve is y=-1.22364+0.28804x-0.00771x2. After analysis of variance, the fitting curves above have a good fitting degree with small error which can precisely reflect the relationship between physiochemical indicator and salinity. In the range of15-18.7°Be, the ammoniacal nitrogen content of soy sauce on56d goes up as salinity increases, while in the range of15-18.7°Be, the ammoniacal nitrogen content declines as salinity rises.3. Using HS-SPME-GC/MS to detect flavor substances of soy sauce fermenting with two kinds of technologies, the fitting curve were got between characteristic flavor substance content of low-salt solid-state soy sauce on25d and fermentation temperature, which is y=1711.53-74.88x+1.11x2, and the fitting curve between characteristic flavor substance content of high-salt diluted-state soy sauce on56d and salinity, which is y=-3349.1+440.05x-11.77x2. After analysis of variance, the fitting curves above have a good fitting degree with small error which can guide the production of soy sauce with better flavor.4. By studying multi-strain high-salt diluted-state fermented soy sauce, it was found that adding Zygosaccharomyces rovxii, Tetragenococcus halophila and lactic acid bacteria gave the highest content of characteristic flavor substances. The fitting curve of the content changing with time is y=176.42-8.31t+0.66t2-0.00405t3. Based on the investigation to its extreme value, the best fermentation period is102d.