Research On The Method Of Fish Sauce Fermentation With Multi-strain

This paper studied fish sauce fermentation with seafood scraps as raw material.Aimed at selecting the best efficient Aspergillus oryza through laser mutagenesis techniques and optimizating the fermentation conditions accrording the physiological and biochemical characteristics of the strain.Fish sauce is a traditional seafood in China,which has thousands of years of production history.The technology of fish sauce prouction is not mature enough within such a short time. In this study, I will optimize fish sauce fermentation process from two aspects, to enhance nutrition and the taste of fish sauce. Aspergillus oryzae is the main strain in fish sauce fermentation,which is rich in enzymes with high activity of protease production, fast growth, adaptability, and do not produce toxins and other characteristics, is widely used for fish sauce production and can form the unique color, aroma, flavor.This research is chosen the Aspergillus oryzae which is isolated in our laboratory to be irradated using the He-Ne laser (X=632.8nm, output power of12mw), the irradiation spot diameteris1.5mm, irradiation distance is30cm.Detecting the spore production and the protease activity of th mutagenic strain by irradating the strain with different time0,1,2,4,6,8,10min. The reault is to irradate the strain6min as the ultimate mutagenic time.Eventully the spore production could reach to8.20×106/ml (48h),, the protease activity increased from1058.68U/g to3260.37U/g, which is greatly enhancing the protease activity of Aspergillus oryzae.The concentration of salt in the fermentation process, the percentage of the Aspergillus oryzae and insulation temperature of the soybean,which three aspects can affect the final nutritional value and taste flavor of fish sauce from different angles. This experiment is to consider growth conditions of Bacillus subtilis from the growth temperature and pH in the fermentation environment and salt tolerance. By measuring the absorbance values of the fermentation liquid at600nm in different temperature of25℃,30℃,35℃,40℃,45℃,50℃,the result says that Bacillus subtilis can grew well at the range from30to45℃;By measuring the absorbance values of the fermentation liquid at600nm in different pH4.0,5.0,6.0,7.0,8.0, the result says that Bacillus subtilis can grew well at the pH range from5.0to8.0environment; By measuring the absorbance values of the fermentation liquid at600nm in different salt content of0.9%,7.0%,13%,19%,25%, the result says that Bacillus subtilis can grew well at salt content of7.0%,Ensureing that the bacteria can growth within the above range, Bacillus subtilis can be guaranteed to play a good role in the process of fish sauce fermentation.Controling the range of conditions mentioned above, began to fermentation with the multi-strains with koji, Bacillus subtilis and the Yeast. Selected the amino nitrogen as an index to explore the salt concentration of the fermentation liquid, the percentage of koji and the insulation temperature. The test ultimately determine salt content of the fermentation liquid is9%, the the percentage of koji of20%, and the temperature of post-insulation was controlled at40℃. Under these conditions, the amino nitrogen content of0.633g/100ml after12d fermentation.