Study On Sour Fermented Soybean Drink

In this study soybeans were used to produce a good quality of fermented soybean drink. Thiscan increase the range of raw materials and reduce the production cost. This paper investigatedthe activity of anti-nutritional factors in soybean milk, the fermentation process of pure soybeanmilk and the process of fermenting soybean milk drink.Activities of trypsin inhibitor and urea enzyme, the protein and the solid contents of soybeanmilk were determined under different heat treatments. According to the results of analysis onactivities of trypsin inhibitor and urea enzyme of some soybean milk sold on market, the safesoybean milk could be obtained at the optimal heat treatment condition of blanching at 95℃ for8min.The remaining rate of trypsin inhibitor of soybean milk under this condition was 10.6%, theurea enzyme was inactive, the protein and solid content were 32.7 g/l and 6.54% respectively.S. theumophilus and L. bulgaricus used for fermenting soymilk were obtained by selectingand taming them in different contents of soybean and cow milk. The acidity of soybean yoghurtby using St and Lb after taming was 60.7oT which was 2.3 times higher than that using Hansen'sYF-L811 and 1.6times higher than that using Rhodia's LB340 and MY BID 11.Based on orthogonal experiment and organoleptic analysis results, the optimum germinationconditions were as follow: soybean: water = 1:8,St:Lb=1:2, pasteurisation conditions were 85℃for 30min, the chosen amount of sucrose and glucose to be added were 6% and 2% respectively ,and the fermentation conditions were 43℃ for 6h. 23 flavor components were identified insoybean yoghurt by GC-MS and the main components were 2,3-diacetyl,acetyl-propiony,amylalcohol and hexanal.PGA and CMC-Na (FH-9) were the chosen stabilizers. Based on the orthogonal experiment,the optimum added amount of stabilizers and homogenizing and sterilization parameters wereobtained. The results indicated that the best formula of this kind of fermented soybean drink withthe greatest stability were: 0.4% of CMC-Na(FH-9),0.2% of PGA, 0.067% of MG and 0.083%ofSE, homogenizing twice under 40℃,30MPa and pasteurizing twice under 80℃ for 20min. Thesensory ,physical, chemical and microorganism target of fermented soybean drink were studiedand conformed to the Chinese Standards.