Biodegradable edible films are both economically and environmentally important to the food industry as packaging and coating materials, as the industry seeks to find a replacement to traditional petroleum-derived synthetic polymers. The overall goal of this thesis was to design a canola protein isolate (CPI)-based biodegradable and edible film that provides excellent mechanical, optical and water vapor barrier properties. A better understanding of the potential of CPI for use as a film-forming ingredient could lead to enhanced utilization and value of the protein for food and non-food applications. In study one, the mechanical, optical and water vapor barrier properties of CPI-based films were investigated as a function of protein (5.0% and 7.5% w/w) and glycerol (30%, 35%, 40%, 45%, and 50% w/w of CPI) concentrations. Overall, as the glycerol concentration increased for the 5.0% and 7.5% CPI-based films, mechanical strength and flexibility decreased and increased, respectively. Film strength was also found to increase at the higher protein concentration; however corresponding changes to film flexibility differed depending on the testing method used. For instance, puncture deformation testing indicated that film flexibility was reduced as the CPI concentration was raised, whereas tensile elongation testing indicated no change in extensibility between the two CPI concentrations. Film transparency was found to increase with increasing levels of glycerol and decreasing levels of CPI, whereas water vapor permeability was found to increase with increasing levels of both glycerol and protein. In study two, mechanical, optical and vapor barrier properties of CPI-based films were evaluated as a function of plasticizer-type (50% (w/w of CPI), glycerol, sorbitol, polyethylene glycol 400 (PEG-400)) and fixative condition (0% and 1% (w/w of CPI), genipin). CPI films prepared with sorbitol were significantly stronger than films with PEG-400, followed by films with glycerol, whereas the flexibility of CPI-based films with glycerol was higher than films with PEG-400, followed by films with sorbitol. In all cases, films prepared with genipin were stronger and less malleable than un-cross linked films. CPI films with glycerol were more transparent than films with sorbitol, followed by films with PEG-400, and the addition of genipin significantly increased the opacity of CPI films. CPI films prepared with glycerol also showed poorer water vapor barrier property than films with PEG-400, followed by films with sorbitol, however, no differences were observed in the presence and absence of genipin. In summary, as the plasticizer concentration increased or protein concentration decreased, CPI films became weaker, more flexible and clearer; however their water vapor barrier properties became poorer as both plasticizer and protein concentration increased. Moreover, CPI films with sorbitol and genipin were found to be stronger, less malleable and permeable to moisture than CPI films with or without genipin, and in the presence of glycerol or PEG-400. Overall, CPI could be considered as a potential material for the development of biodegradable edible packaging in the future.

The overall goal of this thesis is to better understand mechanisms governing associative phase separation within admixtures of plant proteins (e.g., pea and canola) and anionic polysaccharides (e.g., gum Arabic, alginate or é-carrageenan). The process involves the electrostatic attraction between two biopolymers of opposing charges, and typically results in the formation of both soluble and insoluble complexes during an acidic pH titration. If successful, polysaccharides could be triggered to coat the proteins surface to give novel, and hopefully improved functionality as ingredients for food and biomaterials.<p> In the first study, the effect of protein enrichment and pH on the formation of soluble and insoluble complexes in admixtures of pea legumin (Lg) and vicilin (Vn) isolates with gum Arabic (GA) was investigated by turbidimetric, surface charge and fluorometric measurements. The solubility of the protein isolates and mixed biopolymer systems was also studied as a function of pH. Enrichment of the crude Lg and Vn isolates by low pressure liquid chromatography led to a shift towards higher pHs at the onset of soluble complex formation in the presence of GA for both protein isolates, whereas the onset of insoluble complex formation was unaffected. Complexation of the Lg (or Vn) isolates with GA resulted in a shift in the pH where neutrality (zeta potential = 0 mV) occurred to lower pH values, relative to the Lg (or Vn) isolates alone. In the case of the enriched Vn isloate, changes to its tertiary structure were observed by fluorometry upon complexation with GA, whereas no changes were found for the enriched Lg isolate. Complexation of Lg and Vn isolates with GA also had little effect on their solubilities relative to protein alone solutions.<p> In the second study, the formation of soluble and insoluble complexes, and the nature of their interactions as determined by optical density analysis, were investigated in admixtures of canola protein isolate (CPI) and anionic polysaccharides (alginate and é-carrageenan) as a function of pH and biopolymer weight mixing ratio. The solubilities of formed complexes were also investigated versus protein alone. In both CPI-polysaccharide systems, critical pH associated with the onset of soluble and insoluble complexes shifted to higher pHs as the mixing ratios increased from 1:1 to 20:1 (CPI:polysaccharide), and then became constant. There complexes formed primarily through electrostatic attractive forces with secondary stabilization by hydrogen bonding. The solubilities of the CPI-alginate complexes were significantly enhanced relative to CPI alone or CPI-é-carrageenan, which were similar.

The overall goal of this thesis is to better understand mechanisms governing associative phase separation within admixtures of plant proteins (e.g., pea and canola) and anionic polysaccharides (e.g., gum Arabic, alginate or é-carrageenan). The process involves the electrostatic attraction between two biopolymers of opposing charges, and typically results in the formation of both soluble and insoluble complexes during an acidic pH titration. If successful, polysaccharides could be triggered to coat the proteins surface to give novel, and hopefully improved functionality as ingredients for food and biomaterials.<p> In the first study, the effect of protein enrichment and pH on the formation of soluble and insoluble complexes in admixtures of pea legumin (Lg) and vicilin (Vn) isolates with gum Arabic (GA) was investigated by turbidimetric, surface charge and fluorometric measurements. The solubility of the protein isolates and mixed biopolymer systems was also studied as a function of pH. Enrichment of the crude Lg and Vn isolates by low pressure liquid chromatography led to a shift towards higher pHs at the onset of soluble complex formation in the presence of GA for both protein isolates, whereas the onset of insoluble complex formation was unaffected. Complexation of the Lg (or Vn) isolates with GA resulted in a shift in the pH where neutrality (zeta potential = 0 mV) occurred to lower pH values, relative to the Lg (or Vn) isolates alone. In the case of the enriched Vn isloate, changes to its tertiary structure were observed by fluorometry upon complexation with GA, whereas no changes were found for the enriched Lg isolate. Complexation of Lg and Vn isolates with GA also had little effect on their solubilities relative to protein alone solutions.<p> In the second study, the formation of soluble and insoluble complexes, and the nature of their interactions as determined by optical density analysis, were investigated in admixtures of canola protein isolate (CPI) and anionic polysaccharides (alginate and é-carrageenan) as a function of pH and biopolymer weight mixing ratio. The solubilities of formed complexes were also investigated versus protein alone. In both CPI-polysaccharide systems, critical pH associated with the onset of soluble and insoluble complexes shifted to higher pHs as the mixing ratios increased from 1:1 to 20:1 (CPI:polysaccharide), and then became constant. There complexes formed primarily through electrostatic attractive forces with secondary stabilization by hydrogen bonding. The solubilities of the CPI-alginate complexes were significantly enhanced relative to CPI alone or CPI-é-carrageenan, which were similar.