Processing and characteristics of canola protein-based biodegradable packaging: A review

Citation

Zhang, Y., Liu, Q., Rempel, C. (2018). Processing and characteristics of canola protein-based biodegradable packaging: A review. Critical Reviews in Food Science and Nutrition, [online] 58(3), 475-485. http://dx.doi.org/10.1080/10408398.2016.1193463

Plain language summary

Canola meal has a protein content of up to 37% after oil extraction. However, its direct use as a food protein source is prevented by its undesirable components such as glucosinolates and phytate. Interest is growing in developing Canola protein isolate (CPI)-based bioplastic products due to its comparable mechanical and moisture barrier properties with other plant proteins. CPI-based films have great potential in food packaging applications. They could be applied between food components or on the surface of the food system in order to inhibit the migration of moisture, oxygen, carbon dioxide, aromas, and lipids. They can also be used for food wraps, or heat-sealed to form sacks, sachets, pouches, or bags to contain dry foods or ingredients. However, low mechanical properties and poor water vapour resistance are still major challenges for the CPI-based bioplastics. More intensive research is needed for CPI-based film use and optimization. Future research should focus on the improvement of mechanical and barrier properties of CPI-based products.

Abstract

Interest increased recently in manufacturing food packaging, such as films and coatings, from protein-based biopolymers. Among various protein sources, canola protein is a novel source for manufacturing polymer films. It can be concentrated or isolated by aqueous extraction technology followed by protein precipitation. Using this procedure, it was claimed that more than 99% of protein was extracted from the defatted canola meal, and protein recovery was 87.5%. Canola protein exhibits thermoplastic properties when plasticizers are present, including water, glycerol, polyethylene glycol, and sorbitol. Addition of these plasticizers allows the canola protein to undergo glass transition and facilitates deformation and processability. Normally, canola protein-based bioplastics showed low mechanical properties, which had tensile strength (TS) of 1.19 to 4.31 MPa. So, various factors were explored to improve it, including blending with synthetic polymers, modifying protein functionality through controlled denaturation, and adding cross-linking agents. Canola protein-based bioplastics were reported to have glass transition temperature, Tg, below −50°C but it highly depends on the plasticizer content. Canola protein-based bioplastics have demonstrated comparable mechanical and moisture barrier properties compared with other plant protein-based bioplastics. They have great potential in food packaging applications, including their use as wraps, sacks, sachets, or pouches.