Impact of graphite oxide at different oxidation times on barrier and mechanical properties of canola protein-based films.

Canola protein obtained from canola meal, a by-product of the oil extraction process, could be a sustainable option to produce food packaging materials because it has film-forming properties, but it possesses some functional limitations that need to be improved. The present study aims to improve properties in canola-based protein biofilms added with graphite oxide (GO). GO at different oxidation times (0, 15, 30, 60, and 120 min) were exfoliated at different addition levels in canola protein films (0.25, 0.5, 1, and 3%). C/O ratio was reduced in the GO oxidation process, XPS and FTIR demonstrated the functional group added. These functional groups can bond with amino and carboxyl groups in canola protein and enhance the film properties. A significant improvement (p < 0.05) in functional properties was found in GO at more oxidation time (60 and 120 min) and added at 3%. In tensile properties, tensile strength and elastic modulus had better results in 60 and 120 min to oxidation time with 3% to addition level, increasing 200% and 481.72%, respectively, compared to control. Barrier properties are important in food packaging; GO in canola protein improves these properties. Oxygen permeability was reduced to 37.57 x 10-3 cm3 m /m2 day Pa in control films from 5.65 x 10-3 cm3 m /m2 day Pa, in GO at 120 min to oxidation time and 3% to additional level. Water vapor permeability was reduced to 0.09 from 0.06 g mm/m2 kPa h in control and GO120 at 0.5%, respectively. The contact angle of the controlled canola films was increased up to 370% when GO was added into the films, indicating improved hydrophobicity in the material. Canola protein films added with GO are a good alternative to improve the properties of biofilms and could be a good option in developing sustainable packaging.