Study On The Properties Of Wood Glue Adhesive Based On Soybean Protein By Superfine Grinding

In this study,the low temperature defatted soybean meal was used as the raw material,and the defatted soybean flour(DSF)with different particle size distribution was obtained by jet mill.The effects of particle size on the functional properties and structural characteristics of soybean protein and the application of defatted soybean powder in wood adhesive were investigated.In order to provide theoretical guidance for the application of soybean protein.The results were as follows:(1)The effect of superfine grinding on the functional characteristics of defatted soybean meal was investigated.Low-temperature defatted soybean meal as raw material was grinded by buller mill and jet mill,achieving different particle size distribution of defatted soybean flout(DSF).Effects of the particle size of defatted soybean meal functional properties were investigated.The results showed that the solubility,foaming,emulsification and stability of DSF were significantly increased with the decrease of the size of defatted soybean powder.There was no significant change in foam stability.The reduction of emulsifying activity and viscosity was significant.The defatted soybean powder at 15.11 ?m and 12.58 ?m had good functional characteristics.(2)The effect of superfine grinding on the structure characteristics of defatted soybean flour was studied.The effect of particle size on the structure characteristics of defatted soybean powder was studied by using the degreasing soybean powder with different particle size as the test material,the sulfhydryl content,surface hydrophobicity and SDS-PAGE electrophoresis of the defatted soybean powder were determined.The results showed that with the decrease of the size of the defatted soybean powder,the content of sulfhydryl group and total sulfhydryl group showed significantly increase then decrease.The surface hydrophobicity of defatted soybean powder after superfine grinding was significantly improved.But the surface hydrophobicity trend was decreased with the further decrease of particle size.Superfine grinding can reduce the molecular weight of the defatted soybean powder and the protein molecular chain extension.(3)The effect of superfine grinding on the gluing characteristics of soy protein adhesive was studied..In this paper,soybean protein glue with appropriate concentration of soybean protein with different particle size was selected to determine its viscosity and solids content,and the effect of the particle size and concentration of defatted soybean powder on the gluing characteristics of soybean protein glue was studied.The results showed that with the decrease of defatted soybean flour particle size,the viscosity of the soybean protein adhesives was significantly decreased,the solids content was reduced after the first increase trend.The shear strength of 25% concentration of soybean protein based adhesives was determined.The results showed that the water resistance was poor when the defatted soybean meal size was larger.The soybean protein based adhesive had better water resistance and had the potential to improve its water resistance.(4)The effect of modification methods on the gluing characteristics of superfine grinding soy protein adhesive was studied..The samples(SF-5,SF-6,SF-7)were selected to modify soybean protein adhesives by different modification methods(sodium dodecyl sulfate(SDS),polyethyleneimine(PEI),epoxy resin(EP),heat treatment,as well as the method of the compound modification(SF/PEI/SDS/EP,SF/PEI/SDS,TSF/SDS/EP)).The results showed that the modified method of SF/PEI/SDS/EP modification of soybean protein adhesive degree was higher,solids content was significantly higher than that of control group,the modified soy protein based adhesive wet shear strength was greater than the national standard 0.7 MPa.(5)Process optimization of composite modification of soybean protein adhesive by superfine grinding.The modified method of SF/PEI/SDS/EP modification of soybean protein based adhesive was selected,and the applicability of soybean protein based adhesive was improved by single factor experiment and orthogonal experiment optimization.The results showed that the adhesive strength of soybean protein based adhesive prepared by optimized soybean protein adhesive was 1.06 MPa,which was greater than the national standard,when the soybean protein glue concentration was 25%,and the modified particle size of these soybean flour was 15.11 ?m.