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

Authors: LI, JUN - Kansas State University; Lin, Haijing; Bean, Scott; SUN, XIUZHI (SUSAN) - Kansas State University; WANG, DONGHAI - (NCE, CECR)networks Of Centres Of Exellence Of Canada, Centres Of Excellence For Commercilization A

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/23/2020
Publication Date: 8/27/2020
Citation: Li, J., Lin, H., Bean, S.R., Sun, X., Wang, D. 2020. Evaluation of adhesive performance of a mixture of soy, sorghum and canola proteins. Industrial Crops and Products. https://doi.org/10.1016/j.indcrop.2020.112898.
DOI: https://doi.org/10.1016/j.indcrop.2020.112898

Interpretive Summary: To improve the adhesive performance of soy protein based adhesives and reduce the cost of such adhesives, this project investigated the influence of adding sorghum and canola proteins on adhesion properties of soy protein. Mixtures of canola, sorghum and soy proteins were tested for dry, wet and soaked adhesive strengths. A mixture made of 2 parts canola protein, 3 parts sorghum protein, and 5 parts soy protein was found to have the best overall adhesive performance. Compared to the soy protein only, this mixture had a 63% increase in dry adhesive strength, 103% increase in wet strength, and 61% increase in soaked strength. The protein mixture also had a better dry adhesive strength than any individual protein. This research demonstrates that use of mixed protein samples improves adhesive properties compared to using soy proteins alone and provides data to support increased utilization of proteins for bio-based adhesives.

Technical Abstract: Soy protein has been the most widely researched protein-based adhesive; however, soy protein remains an expensive product and is used in both food and feed industries providing competition for the use of soy protein as an adhesive. To improve the adhesive performance of soy protein based adhesives and reduce the cost of such adhesives, this project investigated the influence of adding sorghum and canola proteins on adhesion properties of soy protein. The physiochemical properties of different protein samples were characterized through rheometer, Fourier transform infrared spectroscopy, size exclusion chromatography, and surface hydrophobicity analysis. Mixtures of canola, sorghum and soy proteins were tested for dry, wet and soaked adhesive strengths. A mixture made of 2 parts canola protein, 3 parts sorghum protein, and 5 parts soy protein was found to have the best overall adhesive performance. Compared to the soy protein only, this mixture had a 63% increase in dry adhesive strength, 103% increase in wet strength, and 61% increase in soaked strength. The protein mixture also had a better dry adhesive strength than any individual protein. Protein analysis showed that the improved adhesive performance was likely due to optimizing molecular weight distribution and hydrophobicity.