Study On Stablity Of Combination Of Dry Heat Pretreatment In Whole Soymilk With Enzymatic Hydrolicess Method

Because of long soaking time of soybean,beany flavor of soymilk,and soybean dregs are diacarded.Our aim was to develop dry heating whole soymilk with enzymatic hydrolicess method,which resolved beany flavor of soymilk and improved taste and stability of dry heating whole soymilk.Firstly,the condition of dry heating was dry heating temperature 100 ? and dry heating time 15 min,which was determined and optimized by the relative lipoxygenase activity and nitrogen dissolution index.Under the condition,the relative lipoxygenase activity was 0.29%,48.00%nitrogen dissolution index.Secondly,single factor experiment and orthogonal experiment were used to optimize the enzymatic hydrolysis of alkali protease.Enzyme temperature,pH,enzyme concentration and enzyme time were selected as influencing factors and the ratio of free amino nitrogen of whole soymilk as evaluation index to do the orthogonal optimization test,then we made the conclusion that the best condition of enzymatic hydrolysis of enzyme temperature was 55 ?C,pH 9.5,enzyme concentration 1.50%and enzyme time 135 min.Under the condition,the ratio of free amino nitrogen had increased from 0.50 mg/mL to 1.35 mg/mL,the content of soluble solids had increased from 6.8%to 7.5%,the rate of centrifugal sedimentation had decreased from 39.23%to 37.23%,particle size had decreased and in the surface of whole soymilk appeared flocs and holes,a-helical structure and ?-sheet changed into random coil and ?-tum structure,ensory score had increased from 82.0 points to 84.1 points.Thirdly,single factor experiment and orthogonal experiment were used to optimize the enzymatic hydrolysis of compound cellulose.Enzyme temperature,pH,enzyme concentration and enzyme time were selected as influencing factors and the rate of centrifugal sedimentation as evaluation index to do the orthogonal optimization test,then we made the conclusion that the best condition of enzymatic hydrolysis of enzyme temperature was 50 ?,pH 8.5,enzyme concentration 2.00%and enzyme time 10 h.Under the condition,the content of soluble solids had increased from 7.5%to 9.2%,the rate of centrifugal sedimentation had decreased from 37.23%to 29.56%,particle size had decreased,the surface of whole soymilk appeard to wrinkles and protrusions and sensory score had increased from 84.1 points to 87.2 points.Lastly,single factor experiment and orthogonal experiment were used to optimize the condition of combination of colloids.carrageenan,xanthan gum and gelatin were selected as influencing factors and the rate of centrifugal sedimentation as evaluation index to do the orthogonal optimization test,then we made the conclusion that the best condition of combination of colloids was carrageenan 0.15%,xanthan gum 0.01%and gelatin 0.04%.Under the content of soluble solids had increased from 9.2%to 9.6%,the rate of centrifugal sedimentation of whole soymilk had decreased from 29.56%to 26.29%,and sensory score had increased from 87.2 points to 90.5 points.In conclusion,the problem of soybean soaking time and beany flavor of soymilk were solved,compared with hot-humid soymilk,the content of soluble solids had increased from 5.8%to 9.6%,the rate of centrifugal sedimentation of whole soymilk had decreased from 36.13%to 29.56%,and sensory score had increased from 80.1 points to 90.5 points.The feasibility of enzymatic hydrolysis of whole soymilk by dry heating whole soymilk was proved,which provided basic data for dry heating whole soymilk.