Extraction Of Glycopeptide By Ultrasound-enzymatic Modification From High-temperature Denatured Soybean Meal And Its Structure-activity

High-temperature denatured soybean meal was by-product of soybean oil solvent extraction,which is desolventized by means of high-temperature desolventizing.In China,high-temperature denatured soybean meal as a higher cost performance plant protein resources with high yield and wide source.High-temperature denatured soybean meal,which contains 40-50% protein,was an excellent source of protein and the high value of exploitation and utilization by the attention of scholars.However,the thermal-processing resulting in the heat-denaturation of protein renders soybean meal low solubility of protein,which limit its application in food processing.If the heat-denatured protein in high-temperature denatured soybean meal could be refunctionalized,the more benefits of high-temperature denatured soybean meal can be realized.In this study,we studied the ultrasound-enzymatic modification,extraction,purification,physical and chemical properties and structure feature of glycopeptide from high-temperature denatured soybean meal.These study results could improve the utilization level of high-temperature denatured soybean meal resources,promote the comprehensive development of high-temperature denatured soybean meal and rich active glycopeptide type and function,which has important important theoretical and realistic significance.The main results are as follows:1.High-temperature denatured soybean meal treated by ultrasonic-cellulase was studiedThe optimal conditions were determined as follows,when ultrasound combined synchronous with cellulose,ultrasonic power was 300 W and ultrasonic time was 20 min,concentration of substrate was 8.36%,amount of cellulose was 646 U/g,p H value of 4.1 for cellulose hydrolysis,the amount of soluble polypeptide and polysaccharide were 18.51±0.36% and 10.83±0.32%.2.High-temperature denatured soybean meal treated by protease was studiedThe results showed that,when additive amount of phytase was 61200 U/g,protease hydrolysis pH of 9,enzymatic hydrolysis duration of phytase was 3 h,protease hydrolysis temperature of56.4 °C the amount of soluble polypeptide and polysaccharide were 25.47±0.81% and13.22±0.49%.3.The glycopeptide extraction processingBased on the FRAP and O2-radical of products test,a novel glycopeptide with highest antioxidant activity was obtained from High-temperature denatured soybean meal by ethanol precipitation and purified by DEAE-Cellulose 52 ion exchage chromatography and Sephadex G-25 gel chromatography.4.The analysis of physical and chemical properties of glycopeptideSDS-PAG Electrophoresis detection showed that glycopeptides was a single band,its weight-average molecular weight is 4383 Da which the protein content of glycopeptides was61.28±0.83% and the sugar content was 29.76±0.26%.NSI of the glycopeptides from soybean meal at different p H levels was greater than 80%.The thermal denaturation temperature of glycopeptides was 109.9°C tested by differential scanning calorimetry,while removal of glycan chain of thermal denaturation temperature of 80.3 °C,denaturation enthalpy value was 120.6 J/g.Meanwhile,the ultrasound-cellulose and protease modification method applied to enhance the able of FRAP of glycopeptides and the able of inhibiting of O2-free-radical activities.5.The analysis of structure feature of glycopeptideThe structure information of glycopeptide from high-temperature denatured soybean meal was obtained from amino acid composition test,β-elimination reaction,infrared spectrometry,circular dichroism spectroscopy.The results showed that the highest content of amino acid was glutamic acid followed aspartic acid and lysine.The glycopeptides linkage type of glycopeptide from high-temperature denatured soybean meal was O-linked,the glycan of glycopeptide was pyranose with α-glycosidic bond structure.Circular dichroismdata analysis showed that there was4.7% α-helix,25.6% β-strand,19.2% β-turns and 51.5% unordered in glycopeptide.This research can provide references for the develop high-temperature denatured soybean meal in the field of food development and utilization.