Soy protein adhesion enhanced by glutaraldehyde crosslink

Soy protein has been considered as an alternative to partly replace petroleum-based polymers for adhesive applications. The weakness of protein-based adhesive is poor water resistance, which limits its outdoor applications. The objective of this research was to improve the water resistance of soy protein adhesive by introducing crosslinkage between amino groups of amino acid residue. Laboratory prepared soy protein isolate (SPI) was used in this study. Glutaraldehyde at concentrations of 4, 20, 40, and 80 mu M was used as the crosslinking reagent for SPI modification. Adhesive properties of soy protein modified by glutaraldehyde, as well as thermal and morphological properties, were investigated. Crosslinking-induced protein conformation and structure changes through decrease of amino groups and adding of hydrophobic groups, subsequently affect adhesive performance of SPI. At optimum glutaraldehyde concentration (20 mu M), dry, wet, and soak strengths of modified SPI increased to 31.5, 115, and 29.7%, respectively, compared with unmodified SPI. (c) 2007 Wiley Periodicals, Inc.