Physical Method Assisted Enzymatic Hydrolysis To Extract High-temperature Denatured Soybean Meal Protein And Its Effect On Its Characteristics

High temperature denatured soybean meal is the main by-product of soybean oil extraction,with protein accounting for about 40% ～ 50%.It is rich in nutrients and low in price,making it a high-quality resource for protein extraction.However,due to the high temperature treatment during the extraction process,the protein in soybean meal is severely denatured and difficult to be extracted and utilized.Currently,most of it is used as animal feed,while the rest is directly discarded,which not only wastes resources,but also pollutes the environment.How to extract protein from high-temperature denatured soybean meal has become a key issue to be solved urgently.In this study,high-temperature denatured soybean meal was used as raw material to study the functional characteristics and structure of high-temperature denatured soybean meal protein using ultrasound and low-temperature plasma assisted enzymatic methods,in order to provide useful reference for the high value utilization of high-temperature denatured soybean meal.The main research contents and results are as follows:1.Study on ultrasonic assisted emulsifier defatting of high-temperature denatured soybean meal powderUltrasonic assisted glycerol was used to degrease high-temperature denatured soybean meal.The effects of ultrasound time,temperature,power,glycerol addition,and p H value on the degreasing efficiency of high-temperature denatured soybean meal were investigated using the degreasing rate as an indicator.The results showed that the optimal technological parameters for degreasing were ultrasonic time of 60 min,ultrasonic temperature of 50 ℃,ultrasonic power of 400 w,p H value of 8during the treatment process,and addition of 1.00% glycerol.Under this experimental parameter,the degreasing rate is 90.93%,and the fat content after degreasing is only0.77%.This method not only has a good degreasing effect,but also is simple and feasible,economical and environmentally friendly.2.Study on extraction technology of high temperature denatured soybean meal by protease methodUsing protein extraction rate and hydrolysis degree as indicators,alkaline protease was selected as the best hydrolytic enzyme for high-temperature denatured soybean meal from four tested enzymes: alkaline protease,neutral protease,flavor protease,and complex protease.A single factor experiment was conducted to investigate the effects of the amount of alkaline protease added,substrate concentration,enzymolysis time,enzymolysis p H,and enzymolysis temperature on the protein extraction rate and hydrolysis degree.Based on a single factor experiment,using the protein extraction rate as an indicator,the optimal process combination for alkaline protease hydrolysis of high-temperature denatured soybean meal was determined through a Box-Behnken experimental design,namely,the enzyme addition amount was 5095 U/g,the substrate concentration was 4.4%,the p H value was 9.1,and the enzymatic hydrolysis temperature was 39.8℃.The protein extraction rate obtained under this process condition is 70.03%.3.Ultrasound assisted enzymatic extraction of high-temperature denatured soybean meal protein and its impact on its functional propertiesOn the basis of determining the optimal enzymatic hydrolysis process,ultrasonic assisted enzymatic extraction of high-temperature denatured soybean meal protein was carried out,and the effects of ultrasonic assisted treatment on the extraction rate,functional characteristics,and structure of high-temperature denatured soybean meal protein were investigated.The results showed that ultrasound assisted treatment could change the secondary structure content and micromorphology of high-temperature denatured soybean meal protein,change the spatial conformation of the protein,improve its surface hydrophobicity,and significantly improve its functional properties.After ultrasonic treatment,the emulsifying activity,emulsifying stability,solubility,foaming ability,and oil retention of high-temperature denatured soybean meal protein were increased by 48.13%,56.33%,19.04%,23.33%,and 13.67%,respectively.4.Study on low-temperature plasma assisted extraction of high-temperature denatured soybean meal protein and its impact on its functional characteristicsOn the basis of determining the optimal enzymatic hydrolysis process,low-temperature plasma assisted enzymatic method was used to extract high-temperature denatured soybean meal protein.The effects of low-temperature plasma power,time,and air intake on the extraction rate,functional characteristics,and structure of high-temperature denatured soybean meal protein were investigated,respectively.The study found that low-temperature plasma assisted treatment can significantly reduce the brightness of the protein(P<0.05),change the secondary structure and apparent morphology,and significantly improve its solubility,emulsifying activity,emulsifying stability,foaming ability,and oil retention were significantly improved(P<0.05)by 9.09%,47.84%,50.78%,18.73%,and 37.85%,respectively.