Study On The Optimization Of Soy Sauce Fermentation Condition

Soy sauce is mainly made of soy protein raw materials such as soybeans or soybean meal and starch raw materials, and formed by the microbial fermentation brewing. It is a very common and familiar condiments and also essential for daily cooking. It’s fermentation process involving a wide range of micro-organisms and lasts for months. This makes soy sauce has abundant nutrition and variety of essential amino acid. Soy sauce in dishes can intensify foods’ tasty, also improve the color and nutrition. Color and flavor of soy sauce comes from its unique and long time fermentation process. This article according to actual conditions, made a systematic study on quickly brewing technology of soy sauce, from three parts, the determination of process parameters in the prophase fermentation and late fermentation process to conduct research on soy sauce, the effect of temperature changes in whole fermentation stage. The contents and results are as follows:1. Optimization of prophase fermentation condition Analysis about the effects of additives on activity of protease in media for soy sauce processing. Protease activity was used as the indicator, through single factor experiments during the prophase fermentation to find proteases variation when adding different carbon compounds, nitrogen sources and inorganic salts into media, it turns out that protease activity reaches maximum level when adding glucose, sodium nitrate and zinc sulfate, respectively. We made a response surface analysis based on the single factors experiments. The optimal combination turns out: glucose’s added weight is0.48percent, sodium nitrate’s added weight is0.05percent and zinc sulfate’s added weight is0.02percent and the protease activity goes to1401.87U/g under the optimal combination.2. Optimization of late fermentation condition This part is to explore the impact of fermentation temperature, salt concentration, fermentation time and pH on soy sauce brewing. Amino nitrogen was used as an evaluation index, to test the impact of these conditions on amino nitrogen in the fermentation process. The result shows that pH5.5is good for amino nitrogen generation’s producing, When saline concentration was13percent, amino nitrogen content meet the highest which is0.4912g/100mL.Amino-nitrogen content increased with salted water, however when the salt reaches a certain, the amount of amino nitrogen contents show a declining trend. When raw material and the ratio of salted water is 1:2,amino nitrogen content meet the highest level which is0.4542g/l00mL.We get the optimal conditions by response surface analysis which is Ph chose5.53, saline concentration goes to12.73percent and raw brine ratio is1:56. In this condition, the amino nitrogen content goes to0.6252g/100mL.3. Analysis of temperature effects on fermentation Amino nitrogen was used as an index in this tests, study on the fermentation temperature on the effect of amino-nitrogen in fermentation broth was done, and the protease, ammonium and total nitrogen variation in fermentation broth were also analyzed. The result shows that with the increasing of temperature in early stage, and amino nitrogen content increased, but effect of temperature on amino nitrogen is very low later. In the first5days of fermentation, protease activity is growing rapi100mLy, from began of509.72U/g increased to856.02U/g, and has been smooth growth subsequently; fermentation liquid in the ammonium content always maintained in a low level and has been keep trace of fluctuations; and there was a significant increase of total nitrogen content in the first20days of fermentation, and then gradually to slow until it stabilizes.