Research Of Breeding Aspergillus Oryzae With High Protease Activity And The Multi-strain Mixture Fermentation Conditions Of Soy Sauce

Soy sauce is a traditional condiment in China and has become an indispensable condiment of life, because it has unique flavor and bright color and is rich in nutritional value. Production of soy sauce is most in the world, but the quality is lower. In the international market, the vast majority of high-grade soy sauce is from the market of Japan, Korea and other countries. This is mainly because our relatively brewing business equipment is old and production technology is relatively backward resulting in low utilization of raw materials, low-quality of soy sauce products. Therefore, we must research multi-strain mixture in order to improve the conversion rate of raw protein, increase the flavor of soy sauce, reduce production costs, improve product quality, improve our soy sauce brewing production technology and increase our sauce competitiveness in the international market with scientific research and modern application of fermentation technology.In this paper, the original strain of Aspergillus oryzae Shanghai brewing 3.043 was mutanted with mutagenesis. Through screening and rescreening, a mutant strain of Aspergillus oryzae TZ-04 with high protease activity was screened. After the genetic stability of the experiment, in which the protease activity is above 1700U/g, about 1.8 times than the original strain. And then through the single factor experiment and response surface optimization method the ferment conditions of Aspergillus oryzae TZ-04 strains were optimized. With SAS software analyzing, the most optimal conditions is as follow:material ratio (soybean:wheat bran) was 6: 4, Run water was 1:1, the cooking time of 30min, the natural PH, culture temperature was 28℃, incubation time was 66 h, its neutral protease activity reached the highest. By Aspergillus TZ-04 for validation, and verification test average predictive value close to its capacity optimized than the original conditions, protease activity increased 20.8%.Taking the amino nitrogen, total acid and total nitrogen as responsing value, separating the multi-strain starter bacteria, using the characteristics of more strains and more enzymes, using different proportions of mixing fermentation, the best proportion of four mold daqu of mixing fermentation and the addition of yeast fermentation was obtained through a small pilot test the. Test results were:Aspergillus oryzae TZ-04:Aspergillus niger 3.350:Rhizopus enzyme is 7:1:1:1, fermentation product of this ratio amino nitrogen, total acid and total Nitrogen were the highest aroma of yeast fermentation medium was 2%. Pilot tests using vacuum inoculation, separate multi-strain starter approach to mixed fermentation, the fermentation medium to increase the added aroma soy sauce yeast esters, alcohols, to improve the flavor of soy sauce. Fermented soy sauce with this process amino nitrogen content of 1.37g/100ml, total acid 3.15 g/100ml, total nitrogen content of 2.15 g/100ml, reducing sugar content was 1.41 g/100ml, the total content of ester 145.7 mg/ml, and the red color was 56823EBC means 2.88, and 3.042 used in the factory and Shanghai brewing strains of Aspergillus niger 3.350 pairs of mixed fermentation process compared to 28% respectively,39.4%,18.8%,25.9%,22.2%, 48.5%,36.5%; and multi-strain mixed fermentation nitrogen utilization rate of 87.3%, compared with the control group increased by 12%.