Mechanical and moisture sensitivity of fully bio-based dialdehyde carboxymethyl cellulose cross-linked soy protein isolate films.

Dialdehyde carboxymethyl cellulose (DCMC) crosslinked soy protein isolate (SPI) films were prepared by solvent casting method. Effect of DCMC treatment on mechanical properties, water sensitivity, light barrier properties and thermal stability were investigated. Significant increase in tensile strength (TS) was observed (up to 218%), suggesting occurrence of highly effective crosslinking between SPI and DCMC. Significant improvement in TS compared to other dialdehyde polysaccharide crosslinking agents such as dialdehyde starch is likely due to higher compatibility of DCMC with SPI, as was further confirmed by SEM images. Crosslinking also led to reduction in water vapor permeability and moisture content along with an increase of insoluble mass percentage, indicating improvement in water resistance of these bio-based protein films. Thermal stability of protein films also showed improvement post crosslinking of DCMC.