Hemp (Cannabis sativa) seed oilcake as a promising by-product for developing protein-based films: Effect of transglutaminase-induced crosslinking

Protein concentrates were obtained from hemp seed oilcakes (OCs) and investigated as potential waste-derived source of biodegradable films at different protein and glycerol concentrations and at different pH values. These studies indicated that hemp protein (HP) film forming solutions gave rise to higher performance films when cast at pH 12 in the presence of 50% glycerol (w/w protein) used as plasticizer. Since HPs were demonstrated to act as both acyl donor and acceptor substrates of microbial transglutaminase (mTGase), they have been used as raw material to obtain films also after enzyme treatment. Film morphological characterization demonstrated that mTGase treatment was effective to produce more homogeneous and smoother films, influencing in turn positively their properties. In fact, mTGase-crosslinked films were shown to be more resistant, still flexible and exhibited a higher heat-sealing strength. In addition, the enzymatic treatment of HPs originated bio-plastics with a higher gas permeability and a greater hydrophobicity. These findings suggest the possibility to exploit the mTGase-crosslinked proteins derived from hemp OC as a promising source to produce bio-based materials useful as packaging systems for protecting food products from physical contamination and, thus, for extending their shelf-life