Plastics from an Improved Canola Protein Isolate: Preparation and Properties

Canola meal proteins were solubilized from canola flour at pH 12 using sodium hydroxide solution. Proteins were then precipitated sequentially at pH values ranging from 11 to 3 in decrements of 1 pH unit. The weight distribution and the properties of these fractions were analyzed. The majority (>76%) of the recovered proteins were precipitated at pH values at or below 7. Another substantial fraction was precipitated at pH 11. The functional and thermal property (differential scanning calorimetry) analyses showed that this protein fraction exhibits the highest water holding capacity and lowest melting point. The plastics prepared with refined protein isolates (with pH 11 fraction removed) showed higher water resistance, tensile, and flexural strength, toughness, and elongation values compared to those prepared with standard canola protein isolates. This shows that mechanical and water resistance properties of protein-based plastics can be enhanced using improved protein isolates.