Process And Protein Characteristics Of Alcohol Leached Soybean Protein Concentrate Prepared From Solvent-containing Meal

Alcohol extraction is a commonly used method for the preparation of soy protein concentrate,which has the advantages of low production costs and low pollutant emissions.However,the desolubilisation process in the preparation of low temperature soybean meal is energy intensive and the use of wet meal for direct alcohol extraction will effectively reduce energy consumption.This project uses solvent-containing meal to prepare alcohol leached soybean protein concentrate,to study the influence of alcoholic processing conditions on the extraction effect,to compare the differences in structural and functional properties of alcohol leached soybean protein concentrate prepared from wet and dried soybean solvent-containing meal,and to explore the feasibility of preparing alcohol leached soybean protein concentrate from solvent-containing meal.Firstly,the effects of processing conditions(ethanol concentration,extraction temperature,liquid to material ratio and extraction time)on the extraction effect(protein content,product yield and protein extraction rate)of alcohol leached soybean protein concentrate was investigated.Three conditions were determined for the preparation of soy protein concentrate by combining single-factor and orthogonal experiments.The highest protein content of 66.32% was obtained under the conditions of 65% ethanol concentration,45℃ extraction temperature,6:1 m L/g liquid to material ratio and 50 min extraction time,which was used as the optimal combination for protein content.The protein concentration of the protein concentrate obtained under the conditions of 70% ethanol concentration,45℃extraction temperature,6:1 m L/g liquid to material ratio and 60 min extraction time was65.03% protein and the highest product yield,which was used as the optimized combination of product yield.The protein content of the protein concentrate was 65.33% and the protein extraction rate was the highest when prepared under the conditions of 65% ethanol concentration,50℃ extraction temperature,6:1 m L/g liquid to material ratio and 60 min extraction time.The above three processing conditions were selected for subsequent studies.Secondly,alcohol leached soybean protein concentrates were prepared using different kinds of materials(simulated wet meal,low temperature soybean meal,soybean defatted wet meal and soybean defatted dry meal)and the influence of material characteristics on the functional characteristics of the protein was investigated by using the above process conditions.It was found that in the optimized combination of protein content,product yield and protein extraction rate,compared with the alcohol leached soybean protein concentrate prepared from soybean defatted dry meal,the NSI prepared from soybean defatted wet meal changed from 12.71%,14.03%,10.32% to 15.41%,17.36%,14.37%;foaming properties change from 17.67%,19.33%,16.00% to 19.67%,27.00%,19.33% respectively,while the foam stability changed from 92.48%,91.48%,87.47% to 84.74%,81.42%,84.44%respectively.Compared to the alcohol leached soybean protein concentrate prepared from the dry meal,the protein concentrate prepared from the solvent-containing meal showed no significant change in protein content,increased solubility,water holding capacity,foaming,emulsification and emulsion stability,and decreased oil holding capacity and foam stability.Finally,the structural properties of alcohol leached soybean protein concentrates prepared from different kinds of materials is investigated and the relationship between protein structural properties and functional characteristics is analysed.It was found that in the optimized combination of protein content,product yield and protein extraction rate,the surface hydrophobicity of alcohol leached soybean protein concentrate prepared from defatted dry soybean meal was 36.75 g,35.31 g,42.39 g respectively,and the surface hydrophobicity of alcohol leached soybean protein concentrate prepared from defatted wet soybean meal was 31.48 g,30.91 g and 33.01 g,respectively.The low hydrophobicity of the surface of the alcohol leached soybean protein concentrate prepared from the solvent-containing meal results in an increase in the water holding capacity and a decrease in the oil holding capacity of the protein.Due to the reduced molecular aggregation caused by hydrophobic interactions,the alcohol leached soybean protein concentrate has a smaller average protein particle size and less turbidity in solution and increased protein solubility.Stronger UV absorption,significantly higher free sulfhydryl content,improved protein foaming,emulsification and emulsion stability.