Studies On Soybean Oil And Soybean Protein From The Cold Pressed Soybean Cake By Aqueous Enzymatic Method

Soybean is one of the main oilseed-crops in China. Usually the main usage of soybean is oil extraction and the protein resource hasn't been fully utilized with the soybean cake being used as feeds. But it can be improved in its nutritional and commercial values with the aid of enzymatic hydrolysis. In this study, the technique of aqueous enzymatic extraction was applied to deal with cold pressed cake to develop a new process for extraction of soybean protein and soybean oil. The study also aims to provide a new approach to making good use of cold pressed soybean cake.Research on basic characteristics in the pressing process of soybean for getting oil . Through experiment on soybean with plunger-styled pressing apparatus, approaching the relationship between oil-extracting rate of soybean and press,the relationship between stress and strain in the cold-pressing processing of soybean . The results demonstrate that oil-extracting rate of soybean increases with press, when the press reach 60MPa, whole grain soybean ingress of oil rate attainability 79.99%,shatter soybean ingress of oil rate attainability 76.75%; The relationship between stress and strain of soybean shows nonlinear character.Aqueous enzymatic extraction of soybean protein . The optimum extracting condition is attained by orthogonal experiments as temperature 50℃, pH8.0, ration of stuff to solvent 1:10, extraction time 2.0h, with the product of 88.91% protein content and 0.31% residual oil content.The extracting rate of protein is 67.84% . Neutral protease is used to enzymatically hydrolyze alkaline pretreated cold pressed soybean cake. Relationships among protein content, substrate concentration,enzyme/substrate , duration time , temperature and pH were studied thoroughly.The Response Surface Methodology was adopted to obtain the optimum conditions of the hydrolysis with neutral protease as enzyme/substrate of 0.50% , duration time of 3.09h , temperature of 46.81℃and pH of 6.75, maxima protein yield predicted value is 67.71%.Through three times tests in the condition, average protein yield is 67.43% , and this result shows the chosen four factors value are reasonable, so this also demonstrates the experiment is right.Comparing with the cold pressed cake, the content of amino acids from soybean peptides is higher. The studies show the soybean peptide is better to people.Analysis of property of soybean oil extracted by aqueous enzymatic method. By comparing the physical and chemical properties and the fatty acid composition, it is found that the amount of linoleic acid in aqueous enzymatic extraction soybean oil, more than that in aqueous extraction soybean oil by 22.80%. It can be conferred that soybean oil extracted by aqueous enzymatic method is better to our health.Studies on the functional properties of soybean protein hydrolysates. Functional properties of soybean protein hydrolysates and alkaline extracted protein has also been studied in this paper. Soybean protein hydrolysates is better than alkaline extracted protein in emulsibility,emulsion stability,water-holding capacity,oil sorption and foaming ability,but is slightly weaker in foaming stability,which makes it suitable in meat ware and dairy processing.