Pea protein hydrolysate (PPH) has antihypertensive effects and prostanoids have been implicated in renal diseases. To investigate the role of PPH and prostanoids on renal and cardiovascular effects in cardio-renal disease, normal and diseased Han:SPRD-cy rats were given diets containing either 0, 0.5% or 1% PPH for 8 weeks. At termination, diseased rat kidneys displayed increased renal cyst growth, fibrosis, plasma creatinine and lower monocyte chemoattractant protein-1. Diseased rats also exhibited left ventricular (LV) hypertrophy, elevated systolic and diastolic blood pressures and LV end diastolic and systolic pressures. Four of five prostanoids were elevated in diseased rat kidneys. PPH attenuated systolic blood pressure, but not other components of the cardio-renal syndrome. PPH also increased select prostanoids in normal and diseased rats. Thus, dietary PPH attenuates hypertension in the Han:SPRD-cy rat, but does not ameliorate other components of disease, possibly due to increased prostanoid effects or an insufficient treatment length.

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 protein hydrolysate (PPH) has antihypertensive effects and prostanoids have been implicated in renal diseases. To investigate the role of PPH and prostanoids on renal and cardiovascular effects in cardio-renal disease, normal and diseased Han:SPRD-cy rats were given diets containing either 0, 0.5% or 1% PPH for 8 weeks. At termination, diseased rat kidneys displayed increased renal cyst growth, fibrosis, plasma creatinine and lower monocyte chemoattractant protein-1. Diseased rats also exhibited left ventricular (LV) hypertrophy, elevated systolic and diastolic blood pressures and LV end diastolic and systolic pressures. Four of five prostanoids were elevated in diseased rat kidneys. PPH attenuated systolic blood pressure, but not other components of the cardio-renal syndrome. PPH also increased select prostanoids in normal and diseased rats. Thus, dietary PPH attenuates hypertension in the Han:SPRD-cy rat, but does not ameliorate other components of disease, possibly due to increased prostanoid effects or an insufficient treatment length.

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.

Plant-derived protein such as pea protein is a promising replacement for animal protein and is becoming popular in recent years because of its high nutritional value and potential reduction of environmental footprint. However, the increasing demand for plant-derived proteins is accompanied by the increase of wastes during protein processing such as wastewater containing dilute protein content, which may raise the cost for the downstream processing. Therefore, there is an emerging need to develop novel processing strategies to reduce waste while valorizing useful ingredients. Several researchers suggest that foam fractionation technology can be a viable approach to extract and concentrate protein from dilute wastewater effluent. This technology has already been applied to the chemical and food industry for the extraction of surfactant and animal proteins from wastewater. To design and apply foam fractionation to the plant-derived protein industry, fundamental knowledge on foaming properties of dilute plant-derived protein solution is needed and is currently lacking. Therefore, the objective of this thesis is to advance a fundamental understanding of the foaming properties of dilute pea protein solutions (protein concentration ≤ 1wt%). To achieve the objective, a multiscale approach is used, which is comprised of a detailed investigation of both bulk and interfacial properties of pea protein solutions and foaming properties such as foaming capacity and stability with the help of bubble structure and foam volume kinetics. The focus of this thesis is on the effect of protein concentration. Results demonstrate that protein adsorption kinetics can be characterized by four distinctive regimes: lag phase, diffusion-limited regime, transitional regime, and conformation change regime, which are highly dependent on the protein concentration. However, apparent viscosity is less affected by the protein concentration. Results also show that depending on the protein concentration, two regimes can be distinguished for foam capacity and foam stability. For the first time, these regimes can be rationalized by contrasting characteristics times of protein adsorption kinetics and processing time scale – residence time of bubbles during the foam formation. New findings from this fundamental research will shed light on the control and optimization of foaming properties of plant-derived protein solutions for applications ranging from food processing design to food product development.

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.

No description available.

<p dir="ltr">The impacts of processing on protein structure are of broad interest to the food science community including ingredient producers, product developers, and researchers. Processing and isolation steps induce protein structural changes which occur due to temperature based, shear, and chemical inputs, leading to denatured protein with different functionalities. However, exploration of the protein folding landscape as a way to intentionally modify protein conformation is not widely understood in food science. This particularly applies to cold denaturation, which is the structural changes in protein as the result of low temperature treatments.</p><p dir="ltr">This work has two primary goals. The first was to develop understanding of protein conformations resulting from cold denaturation and its implications for food textural properties. Pea protein was selected for this work since it is a source of plant-based protein that has recently grown in popularity and contains many hydrophobic amino acids that would make is susceptible to cold denaturation. Cold denaturation was studied using physicochemical techniques including differential scanning calorimetry, Fourier transform infrared spectroscopy, zeta potential, fluorescence spectroscopy, dynamic light scattering, and rheology. These techniques are used to characterize untreated pea protein, and proteins that have been modified using different combinations of ethanol, shear forces, acidic conditions, extrusion, and temperatures below 0°C. Significant physicochemical differences are found as the result of low temperatures, driven by an increase in surface hydrophobicity and electrostatic interactions. These differences led to protein gelation through hydrophobic forces, changing the nature of gels. Similarly, the increase in protein hydrophobicity leads to more stable emulsions from these products and unique fatty extrudates.</p><p dir="ltr">A second aim of this work developed bioinformatic models to interpret physiochemical data and provide mechanistic understanding of the process, as well as predict functional properties based on protein models. Strong correlations are found for the zeta potential, secondary structure, hydrogen bonds, and surface hydrophobicity. These models are used to convert data into physicochemical energy and used to provide reasonable estimates of mechanical properties of pea protein in extrusion, gelation, and emulsification. Together, this work shows that cold denaturation may be a useful tool for food product developers creating fatty and creamy textures. It also suggests bioinformatic modeling as a tool to estimate protein functionality, which could lead to tremendous time savings in process and product design.</p>