The focus of this research was to develop a plant-based microcapsule for flax oil by complex coacervation. Complex coacervation involves the electrostatic attraction between two polymers of opposing charges. Specifically, the research aimed to: a) identify the ideal biopolymer and solvent conditions required for complex coacervation involving pea protein isolate (PPI) and gum Arabic (GA); b) understand the functional behaviour of PPI-GA complexes as food and biomaterial ingredients; and c) develop methodologies for encapsulating flax oil within PPI-polysaccharide capsules. Complex coacervation between PPI-GA was found to be optimized at a biopolymer weight mixing ratio of 2:1 in the absence of salt. The functional behaviours of the optimized biopolymer mixture were then investigated as a function of pH (4.30-2.40) within a region dominated by complex coacervation. Emulsion stability was found to be greater for PPI-GA mixture systems relative to PPI alone at pH values between 3.10 and 4.00; emulsions produced under one-step emulsification exhibited higher stability compared to those of two-step emulsification at all pH values. Foam expansion was independent of both biopolymer content and pH, whereas foam stability improved for the mixed system between pH 3.10 and 4.00. The solubility minimum was broadened relative to PPI at more acidic pH values. These findings suggested that the admixture of PPI and GA under complexing conditions could represent a new food and/or biomaterial ingredient, and has potential as an encapsulating agent. Two encapsulation processes were employed in this research: high speed mixing (two-step emulsification) and low speed mixing (one-step emulsification). Flax oil capsules formed using the gelatin-GA mixture (as control) under high speed mixing exhibited low moisture content, water activity and surface oil, and afforded adequate protection against oxidation relative to free oil over a 25 d storage period. The PPI-GA mixture failed to produce acceptable capsules using either high or low speed mixing. In contrast, PPI-alginate capsules were produced and exhibited similar chemical properties as gelatin-GA capsules, except with lower encapsulated flax oil content (30% vs. 50% w/w). However, oxidative stability may adversely affected by the low speed mixing condition during encapsulation.

The focus of this research was to develop a plant-based microcapsule for flax oil by complex coacervation. Complex coacervation involves the electrostatic attraction between two polymers of opposing charges. Specifically, the research aimed to: a) identify the ideal biopolymer and solvent conditions required for complex coacervation involving pea protein isolate (PPI) and gum Arabic (GA); b) understand the functional behaviour of PPI-GA complexes as food and biomaterial ingredients; and c) develop methodologies for encapsulating flax oil within PPI-polysaccharide capsules. Complex coacervation between PPI-GA was found to be optimized at a biopolymer weight mixing ratio of 2:1 in the absence of salt. The functional behaviours of the optimized biopolymer mixture were then investigated as a function of pH (4.30-2.40) within a region dominated by complex coacervation. Emulsion stability was found to be greater for PPI-GA mixture systems relative to PPI alone at pH values between 3.10 and 4.00; emulsions produced under one-step emulsification exhibited higher stability compared to those of two-step emulsification at all pH values. Foam expansion was independent of both biopolymer content and pH, whereas foam stability improved for the mixed system between pH 3.10 and 4.00. The solubility minimum was broadened relative to PPI at more acidic pH values. These findings suggested that the admixture of PPI and GA under complexing conditions could represent a new food and/or biomaterial ingredient, and has potential as an encapsulating agent. Two encapsulation processes were employed in this research: high speed mixing (two-step emulsification) and low speed mixing (one-step emulsification). Flax oil capsules formed using the gelatin-GA mixture (as control) under high speed mixing exhibited low moisture content, water activity and surface oil, and afforded adequate protection against oxidation relative to free oil over a 25 d storage period. The PPI-GA mixture failed to produce acceptable capsules using either high or low speed mixing. In contrast, PPI-alginate capsules were produced and exhibited similar chemical properties as gelatin-GA capsules, except with lower encapsulated flax oil content (30% vs. 50% w/w). However, oxidative stability may adversely affected by the low speed mixing condition during encapsulation.

Gelation properties of a salt extracted pea (Pisum sativum) protein isolate (PPIs) were evaluated with a goal of using this isolate as a meat extender. Microbial transglutaminase (MTG) was used to improve gelation of PPIs, muscle protein isolate (MPI) from chicken breast and the two combined. Gelation properties were evaluated using small amplitude oscillatory rheology and texture analysis. SDS-PAGE and differential scanning calorimetry were used to examine protein structure. Minimum gelation concentration for PPIs was 5%, lower than the 14% obtained for a commercial pea protein isolate (PPIc), possibly because the PPIc undergone denaturation whereas PPIs had not. Storage modulus (G') and loss modulus (G") increased with protein concentration and maximum gel strength for PPIs occurred at pH 4.0 in 0.3M NaCl. Higher or lower pH values affected protein charge and the potential for network formation. Higher salt concentrations resulted in increased denaturation temperatures, to a point where the proteins did not denature at the 95ºC temperature used for gel formation. When both heating and cooling rate were increased, gel strength decreased, though the cooling rate had a greater impact. Chaotropic salts enhanced gel strength, whereas non-chaotropic salts stabilized protein structure and decreased gel formation. Based on effects of guanidine hydrochloride, urea, propylene glycol, β-mercaptoethanol, dithiothreitol and N-ethylmaleimide, hydrophobic and electrostatic interaction and hydrogen bonds were involved in pea protein gel formation but disulfide bond contribution was minimal. Gels formed with MPI at concentrations as low as 0.5% and were strongest at 95ºC, higher than the ~ 65ºC normally used in meat processing. Good gels were formed at pH 6 with 0.6 to 1.2 M NaCl. Addition of MTG increased gel strength for PPIs, MPI, and a combination of the two. SDS-PAGE showed that bands in the 35~100kDa range became fainter with higher MTG levels but no new bands were found to provide direct evidence of interaction between muscle and pea proteins. Improved gel strength for the MPI/PPI mixture (3:1) containing MTG suggested that some crosslinking occurred. Higher heating temperatures and MTG addition led to the formation of MPI/PPI gel and demonstrated the potential for utilization of pea protein in muscle foods.

Gelation properties of a salt extracted pea (Pisum sativum) protein isolate (PPIs) were evaluated with a goal of using this isolate as a meat extender. Microbial transglutaminase (MTG) was used to improve gelation of PPIs, muscle protein isolate (MPI) from chicken breast and the two combined. Gelation properties were evaluated using small amplitude oscillatory rheology and texture analysis. SDS-PAGE and differential scanning calorimetry were used to examine protein structure. Minimum gelation concentration for PPIs was 5%, lower than the 14% obtained for a commercial pea protein isolate (PPIc), possibly because the PPIc undergone denaturation whereas PPIs had not. Storage modulus (G') and loss modulus (G") increased with protein concentration and maximum gel strength for PPIs occurred at pH 4.0 in 0.3M NaCl. Higher or lower pH values affected protein charge and the potential for network formation. Higher salt concentrations resulted in increased denaturation temperatures, to a point where the proteins did not denature at the 95ºC temperature used for gel formation. When both heating and cooling rate were increased, gel strength decreased, though the cooling rate had a greater impact. Chaotropic salts enhanced gel strength, whereas non-chaotropic salts stabilized protein structure and decreased gel formation. Based on effects of guanidine hydrochloride, urea, propylene glycol, β-mercaptoethanol, dithiothreitol and N-ethylmaleimide, hydrophobic and electrostatic interaction and hydrogen bonds were involved in pea protein gel formation but disulfide bond contribution was minimal. Gels formed with MPI at concentrations as low as 0.5% and were strongest at 95ºC, higher than the ~ 65ºC normally used in meat processing. Good gels were formed at pH 6 with 0.6 to 1.2 M NaCl. Addition of MTG increased gel strength for PPIs, MPI, and a combination of the two. SDS-PAGE showed that bands in the 35~100kDa range became fainter with higher MTG levels but no new bands were found to provide direct evidence of interaction between muscle and pea proteins. Improved gel strength for the MPI/PPI mixture (3:1) containing MTG suggested that some crosslinking occurred. Higher heating temperatures and MTG addition led to the formation of MPI/PPI gel and demonstrated the potential for utilization of pea protein in muscle foods.

Pea seeds were tempered at moisture contents of 12.0&amp / #61617 / 0.1, 13.0&amp / #61617 / 0.1, 14.0&amp / #61617 / 0.1 and 15.0&amp / #61617 / 0.3%. The seeds with different moisture contents were then milled and fractioned according to the particle size of 53, 106, 212, 425 and 850 &amp / #956 / m. Tempering the pea seeds (12.0&amp / #61617 / 0.1, 13.0&amp / #61617 / 0.1, 14.0&amp / #61617 / 0.1 and 15.0&amp / #61617 / 0.3%) did not significantly affect the mass and protein fraction in comparison with the pea seeds that are not tempered (11.45&amp / #61617 / 0.05%). For the production of pea protein isolate, aqueous-solvent extraction method was used. The protein was extracted with an alkali solution from the ground pea-seeds and precipitated from the extract by bringing the pH down to isoelectric point (pH=4.5). The precipitated protein was separated from the supernatant by centrifugation. The effects of extraction parameters on the yield of extraction such as pH, particle size, temperature, solvent to solid ratio, and salt were studied. The maximum yields were obtained at these conditions / pH: 12.0 for the alkalinity of the extraction medium, 53 &amp / #956 / m for the particle size, 40&amp / #61616 / C for the extraction temperature, 5.0 for the solvent to solid ratio and 0.0 M for the saline concentration. At these extraction conditions, the maximum protein recovery was 72.75% resulting in a product containing 93.29% protein on a dry basis.

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.

Binding of volatile flavour compounds to plant proteins is known to be an issue, particularly for developers of flavoured gluten-free snacks made with pea protein. This project used a model system to describe the effects of extraction and heat on the binding of hexanal (Hex), hexyl acetate (HxAc) and 2-octanone (2-Oct) to pea protein isolate and to evaluate any resulting change in protein functionality.

<p dir="ltr">Pea protein is one of the most used plant proteins in food products, acting as an alternative to conventional animal protein sources due to its abundant, nutritious, and ease in supply chain characteristics. The objective of this study was to investigate the impact of homogenization and UHT processing parameters on the properties of protein emulsion. Protein emulsions (8% w/w pea protein isolate and 1% w/w sunflower oil) were freshly prepared prior to processing, and the untreated sample was considered as the control (NT). The pilot-scale aseptic processing system (APS) used in this study consisted of two coil-in-shell heaters and two coolers. Samples flowed through each section of the APS system following this order: balance tank, pre-heater, final heater, hold tube, pre-cooler, and final cooler. The homogenizer was located either after the pre-cooler (AC) or the pre-heater (AH) with a controlled temperature of 165F. A third setup was utilized by bypassing the homogenizer in the UHT system. An additional 8-hour continuous run was conducted to mimic a commercial manufacturing operation by recirculating the protein emulsion in the UHT system, and fouling detections were made using a non-intrusive sensor (NICS). 5% w/w soy protein, 1% w/w sunflower oil oil-in-water emulsion was also used for fouling tests. Protein concentration, pH and zeta potential, Cryo-SEM microscopic image, particle size distribution, flocculation index (FI), coalescence index (CI), viscosity and color data were collected and analyzed. The protein concentration had a 23.20 ± 4.00 %, 28.35 ± 5.02 %, 27.98 ± 5.05% and 21.38 ± 5.75% reduction for AC, AH, UHT and NT samples, respectively, when compared with the initial concentration in the formula. AC, AH, UHT and NT samples had pH values of 7.24 ± 0.01, 7.27 ± 0.01, 7.28 ± 0.02, 7.41 ± 0.01, and zeta potential values of -42.91 ± 0.89, -47.30 ± 0.91, -46.91 ± 1.40 and -50.11 ± 1.47 mV. AC sample had a smaller and NT sample had a bigger, respectively, mean weighted size D 4,3 value than AH and UHT samples, which could also be seen in Cryo-SEM images where only AC images contained more visually observable smaller particles. FI and CI for AC, AH and UHT indicated the formation of flocs but no irreversible aggregations were found. Shear-thinning AC, AH, UHT and NT samples had viscosity decreases from 4.00 to 3.56, 3.88 to 3.75, 4.02 to 3.79 and 10.42 to 9.56 mPa*s in 1 1/s to 100 1/s shear rate range. NT sample had a very noticeable color difference from the other three treated samples. Overall, AC samples had similar or better emulsion stability in all aspects than AH and UHT samples, suggesting that AC processing could potentially be used in the protein beverage industry for manufacturing products with improved shelf stability. Severe foulants buildups were neither observed nor detected by a non-intrusive continuous sensor (NICS) in the UHT system within 8 hours of process for both pea protein and soy protein emulsion, indicating that this UHT-homogenization processing can potentially be adapted to current industrial practices for higher-quality protein beverages.</p>