Studies On The Key Technics Of Improving Quality Of Fermented Soybean

Labadou is one of the traditional fermented soybean in China. It is rich in theprotein, amino acid and vitamin. With its easy digestion and absorption, pleasanttaste, it is popular with customers. By lately researching, man discovered somefunctional composition in Labadou, such as soybean isoflavones, soybeanpolypeptide, etc. These instance benefit for human body.At present, many enterprises are producing Labadou on industrialization in ourprovince. In process, single Mucor strain is inoculated. This way have someadvantages, such as pure Mucor making starter, simple process, production cycleshortening, only one week. Because single Mucor can not excrete high-activeprotease and form other enzymes in small, the products, which were fermented bysingle Mucor, is inferior to traditional products on flavor and nitrogen of amino acid.During shift period, the hardness of product increase and the hue of product becomedark, even brown, which influence the sale of the product seriously.In this paper, the results of studying on the key technics of improving fermentedsoybean are as fellows.1. Labadou is produced with soybean which is enzymolysised by endogenousenzymes. The hardness of the product is obviously reduced and the cOntent ofnitrogen of amino acid aid reducing sugar increase to a certain extent. The conditionthat the endogenous enzyme of soybean is suitable for function is: 25℃soaking toincrease 1～1.2 times weight, 30℃germinating for 8h to activate endogenousenzyme, 40℃dealing with 6h to enzymolysise macromolecular substance insoybean. The amino nitrogen content of products finally raise by 22.5%, and thehardness of products has been reduced by 37.1%.2.By flat separation and mutant with ultraviolet radiation, high-yield neutral protease Mucor strain A2 and high-yield a-amylase Rhizopus strain C4 werescreened, and the capability of producing enzyme is steady. The two srtains can growrapidly, and the mycelium is dense and white, are fit for producing Labadou.3.Compared with inoculated single Mucor strain A2, Labadou, which wasinoculated both A2 and C4 at the ratio of 7:3, has high and prosperous mycelium,high active neutral protease. Through 4d secondary fermened, the products issuperior to the former on the free amino acid, the nitrogen of amino acid and solublesubstance, the content of them raise by 6%, 31% and 10% respectively. The senseevaluation of the product grades highest, and has remarkable different with the otherproducts.4.It is multifactor result that Labadou is brown. The suitable craft can controlthe browning of Labadou. These crafts are: secondary fermenting for 4d, vacuumpackaging with aluminum foil film and conserving with 10℃. After a host ofexperiments, the results showed that L-cysteine(L-Cys), citric acid(CA) andethylenediamine tetraacetic acid disodium salt(EDTA-2Na) can control browning ofLabadou effectively. Through the orthogonal test, the optimal ratio of threeantioxidants is: L-Cys 0.1%, CA 0.3%, EDTA-2Na0.04%. The results showed thatthe level of addition of L-Cys and EDTA-Na have extremely remarkable differenceand remarkable difference respectively. The product, which is with the optimal ratioof three antioxidants and vacuum packaging with aluminum foil film, can store 90d.