Plywood adhesives derived from prolamin of distilled spent grains (DSG) from Chinese liquor (Baijiu)

Abstract

Distilled spent grains (DSG) are the largest by-product of Chinese liquor (Baijiu) production. To diversify the utilization of rich nutrients that remain in DSG and endow it with high-added value, the possibility of prolamin-based adhesive (PBA) from DSG was innovatively explored in this paper. The prolamin extracted from three aroma and flavor varieties of DSG, namely strong aroma- (SA), soy sauce aroma- (SSA), and light aroma- (LA), were modified by sodium dodecyl sulfate (SDS) and urea. PBA was successfully synthesized with new protein raw materials under two modification methods, and the most efficient additive ratio was applied to the plywood adhesive. Our results showed that the most hydrophobic amino acid content of prolamin ensures PBA with stronger water resistance. PBA-LA-SDS had more advantages in preparing adhesives, demonstrating the maximum dry shear strength with 2.24 MPa. In order to enhance the wet shear resistance of PBA, the cross-linking agent (CA) was incorporated successfully with PBA, achieving a maximum wet shear strength of 1.31 MPa, which was 300 % higher than that of the pristine adhesive. This study would provide guidance for transforming DSG prolamin into wood adhesives and prove that the sustainable development and high-added-value application of PBA is feasible, which will bring new economic benefits to distilleries.