Evaluation of adhesive performance of a mixture of soy, sorghum and canola proteins

Abstract

Soy protein has been the most widely researched protein-based adhesive; however, soy protein remains an expensive product because of its competitive uses in both food and feed industries. To mitigate such competition, this project was aimed to investigate protein composites by mixing low value sorghum and canola proteins into soy proteins. In addition to cost reduction, a novel composite with optimal composition of three protein were identified showing superior adhesion properties. For example, compared to soy protein alone, the optimum protein mixture (sorghum:canola:soy = 3:2:5) had a 63 % increase in dry adhesion strength, 103 % increase in wet adhesion strength, and 61 % increase in soaked adhesion strength. The physiochemical properties of different protein samples were characterized using rheometry, Fourier transform infrared spectroscopy, size exclusion chromatography, SDS-PAGE and surface hydrophobicity analysis. Protein analysis showed that the improved adhesive performance was likely due to optimizing protein molecular weight distribution and hydrophobicity. The present study demonstrates a simple, straight forward approach to improve soy protein-based adhesion performance and also reduce the overall cost of the plant protein-based composites as adhesives.