Canola Protein Isolate Research Articles

Cold gelation of canola protein isolate and canola protein hydrolysates

Canola holds untapped potential as an emerging plant protein source, owing to its promising nutritional and functional advantages. In this study, canola protein isolate (CPI) and its hydrolysates were used to prepare CaCl2-induced cold-set gels. Gel properties were examined through rheological characterization and scanning electron microscopy. CPI was extracted from canola meal using an alkaline extraction or salt extraction methods. The gel prepared from alkali-extracted CPI exhibits clearly higher storage and loss moduli values in a frequency sweep test, indicating that exposing hydrophobic domains at alkaline condition is critical for the cold-set gelation. Enzymatic hydrolysis of alkali-extracted CPI using different concentrations of Alcalase (0.04%, 0.2%, and 1%, w/w), resulted in a decrease in gel strength, primarily due to the loss of high molecular weight constituents. Ultrafiltration of the hydrolysates was employed to concentrate these constituents. Interestingly, at reduced protein concentrations, gels prepared using the retentate fraction (the hydrolysate prepared at an Alcalase concentration of 0.04 %) exhibited higher values of both moduli than that of the CPI gels. This suggests that enzymatic hydrolysis of CPI exposes hydrophobic domains, facilitating aggregate formation and improving gel forming capability. Fourier transform infrared spectroscopy analysis shows β-sheets was increased after hydrolysis and the subsequent ultrafiltration process. This study supports a key role of hydrophobic interactions in the formation of cold-set gelation using alkali-extracted CPI and the retentate fraction of canola protein hydrolysate. These findings offer potential for the development of novel applications of canola proteins in food and non-food industries.

Partial characterization of canola (Brassica napus L.) protein isolates as affected by extraction and purification methods

Canola (Brassica napus L.) meal represents a prominent alternative plant-based source for protein isolation. This work aimed to investigate the combined effect of extraction and purification methods for the production of canola protein isolates (CPIs). CPIs were characterized in terms of process yield, protein recovery, basic composition, amino acid profile, in vitro protein digestibility, techno-functional properties, structural properties, and molecular features. The results showed that the Alk-Uf method enhanced yield (16.23 %) and protein recovery (34.88 %). Meanwhile, the Et-Alk-Uf method exhibited the highest crude protein (89.71 %) and free amino nitrogen (4.34 mg g protein−1) contents. Furthermore, protein digestibility (95.5 %) and protein digestibility corrected amino acid score (1.0) were improved using the Et-Alk-Ac method. Conversely, the amino acid composition, secondary structure, and electrophoretic profiles were generally similar for all CPIs. The Alk-Uf and Et-Alk-Uf methods produced isolates with the highest water solubility (∼39.18 %), water absorption capacity (∼3.86 g water g protein−1), oil absorption capacity (∼2.77 g oil g protein−1), and foaming capacity (∼505.26 %). Finally, the foaming stability (93.75 %) and foaming density (34.38 %) were increased when employing the Alk-Ac method. These findings suggest that, in general, the Alk-Uf and Et-Alk-Uf methods can be used to obtain CPIs with high added value for use in food formulations.

Preparation and Characterization of Carbon Nanotubes Enhanced Canola Protein Isolate (CNT/CPI) Bio-Adhesive for Wood Application

The current wood adhesives technologies rely mainly on formaldehyde-based adhesives produced from petrochemicals. Moreover, these adhesives are derived from non-renewable sources is known to be carcinogenic together with other serious health effects. Therefore, there is an increasing interest in the use of renewable and biodegradable sources for the evolution of an environmentally friendly adhesives for interior wood applications.The canola meal (the remnant after oil extraction from the canola seed) contains about 36 – 39% (8.5% moisture basis) can be used as a low value feed for the animals. Moreover, its protein content is currently exploring other applications such as in the adhesive technology and it can be used as an alternative to the widely used formaldehyde-based adhesives. Canola proteins (CP) as adhesives have many unique properties such as ease of handling, low cost, low pressing temperatures, and the ability to bind wood with relatively high moisture content. On the other hand, it has relatively low adhesion strength and low water resistance which are the major drawbacks. This study will address these issues by modifying CP adhesive with carbon nanotubes (CNT). CNT are one of the most encouraging strengthening nanofillers with the extraordinary tensile modulus and strength, it has been proved to significantly improve the physical and mechanical properties of the nanocomposites. Generally, this study will intend to improve the water resistance and adhesive strength of the CP adhesive by incorporating different concentrations of the CNT into the protein matrix.This study is made up of two parts: incorporation of CNT and functionalized CNT (FCNT) into the CP matrix. Incorporation of CNT at 1% (w/w) enhanced the adhesive strength from 5.98, 1.80, and 5.42 to 9.20, 5.64, and 7.44 at percentage increment of 53.85, 213.33, and 37.27% for dry, wet, and soaked strength respectively. The presence of carbonyl group in the CNT after purification as well as the polyvinylpyrrolidone (PVP) helped to attain this improvement in the water resistance and adhesion.In the second part, functionalization of the CNT greatly improved the shear strength at 1% FCNT concentration to 10.62, 8.10, and 8.13 at 77.59, 350, and 50% increase for dry, wet, and soaked strength respectively. The introduction of the carboxylic group by functionalization significantly improved the mechanical and thermal properties of the CP due to a proper dispersion giving rise for a better hydrophobic and cohesive interactions between the wood and adhesive.These results proved an enhanced water resistance and adhesion of the CP contributed by the CNT and its functionalization.

Bioefficacy and Safety Assessment of Protein Isolates Obtained from Nonconventional Sources

Nonconventional protein isolates were prepared from defatted oilseeds (sesame, flaxseed, and canola). Bioevaluation was performed via growth study parameters i.e., protein efficiency ratio (PER), net protein ratio (NPR), and relative net protein ratio (RNPR). The highest values for these parameters were recorded in sesame protein isolates (SPIs) followed by canola protein isolates (CPIs) and flaxseed protein isolates (FPIs). Nitrogen balance study parameters represented maximum true digestibility (TD) in SPI trailed by FPI and CPI. However, biological value (BV) was found higher in FPI. Similarly, the highest value for net protein utilization (NPU) was noticed in FPI tracked by SPI and CPI. Moreover, safety assessment of protein isolates was also performed including serum protein and kidney and liver function tests. All these parameters showed nonsignificant variations among the tested protein isolates. The outcomes of research explicated that these protein isolates can play a pivotal role to increase the protein level of individuals.

Amino Acid Profiling and SDS-PAGE Analysis of Protein Isolates Obtained from Nonconventional Sources

Proteins play an imperative role in enhancing the nutritional status of the human body. The present study was designed to determine the molecular weight of protein isolates prepared from defatted oilseeds, i.e., sesame, flaxseed, and canola, using SDS-PAGE. The electropherogram revealed protein bands ranging from 15 to 65 kDa. Furthermore, proteins were subjected to amino acid profiling followed by calculation of amino acid score with reference to requirement for preschool children. The amino acid profiling results indicated that sesame protein isolates (SPI) exhibited the highest values for aromatic amino acids, histidine, isoleucine, and valine. However, the maximum values for sulfur-containing amino acids were depicted by flaxseed protein isolates (FPI). Moreover, the lysine content was highest in canola protein isolates (CPI). Results indicated better profile and quality of proteins, capable to meet the requirements of essential amino acids, especially for preschoolers. Moreover, the values for the protein digestibility corrected amino acid score (PDCAAS) and in vitro protein digestibility (IVPD) were also determined. Conclusively, protein isolates from defatted oilseeds exhibit better-quality proteins with a balanced amino acid profile. By potential utilization in numerous food products, these proteins can play a pivotal role in fulfilling the nutritional requirements of individuals, especially in developing economies.

Removal of anti-nutritional factors of rapeseed protein isolate (RPI) and toxicity assessment of RPI.

We prepared a detoxified rapeseed protein isolate (RPI) by phytase/ethanol treatment based on alkaline extraction and acidic precipitation. Contents of protein, fat, ash, moisture, crude fiber, glucosinolates, phytic acid, and phenolics and color were determined. To evaluate the safety of detoxified RPI, five groups of C57 mice (detoxified RPI [10 and 20 g kg-1]; commercial soybean protein isolate (SPI) [10 g kg-1]; non-detoxified RPI [10 g kg-1]; control) were used in the acute-toxicity test. Bodyweight and pathology parameters were recorded at different time points, followed by macroscopic examination, organ-weight measurement and microstructure examination. After pretreatment of rapeseed meals with phytase (enzyme : substrate ratio, 1 : 5 mg g-1) for 1.5 h and two-time ethanol extraction for precipitated protein, the chemical characteristics in RPI were protein (88.26%), fat (0.57%), ash (2.72%), moisture (1.90%), crude fiber (0.77%), glucosinolates (0 μmol g-1), phytic acid (0.17%), phenolics (0.36%) and whiteness (73.38). Treatment resulted in significant removal of anti-nutritional factors (ANFs) and increased whiteness in detoxified RPI compared with non-detoxified RPI, and lower than in cruciferin-rich canola protein isolate (Puratein®). Experimental-related effects on bodyweight, clinical observations, or clinicopathology, in mice treated with detoxified RPI were not observed except for a decreased thyroid gland/parathyroid gland index in mice treated with non-detoxified RPI. Furthermore, the no-observed-effect level (NOEL) was 10 g kg-1 of detoxified RPI, whereas the no-observed-adverse-effect-level (NOAEL) was the highest fed level of 20 g kg-1 of detoxified RPI. Overall, detoxified RPI prepared by the combined treatment of phytase and ethanol was considered safe under the conditions tested, in which the contents of the main ANFs were reduced significantly.

Stability and rheology of canola protein isolate-stabilized concentrated oil-in-water emulsions

Salt-extracted canola protein isolate (CPI) from a cold-pressed meal was used (1–4 wt%) to develop concentrated 50% canola oil-in-water emulsions (pH 7) using a high-pressure homogenizer and the effect of various environmental factors on emulsion stability and rheology was investigated. As CPI concentration increased, droplet size decreased from 16.4 to 3.8 μm while the droplet charge remained constant at around −11 mV. All emulsions flocculated over 30 days but exhibited exceptional resistance to coalescence. Storage moduli of all emulsions were higher than the loss moduli at all CPI concentrations, suggesting a gel-like structure. Emulsion stability was also investigated by adding vinegar (10 wt%, pH 3.7) or salt (1 wt%) or a mixture of both and heating at 80 °C. The addition of either salt or vinegar reduced the viscosity and gel strength of emulsions, compared with the non-treated emulsions. No significant change in microstructure was observed with the addition of either vinegar or salt, but in the presence of both, the droplets were extensively aggregated, leading to a non-flowing strong gel structure with significantly higher viscosity and gel strength. Salt addition led to charge screening, but the droplets remained less flocculated due to steric repulsion, while with acid, higher charge prevented aggregation. When both salt and acid were present, lower charge and change in protein conformation led to extensive droplet aggregation. Heat treatment led to an approximately ten-times increase in gel strength, which could be attributed to CPI thermal denaturation leading to droplet and protein aggregation. These findings may extend the application of CPI in viscoelastic foods such as salad dressing.

Mechanical and Thermal Behavior of Canola Protein Isolate Films As Improved by Cellulose Nanocrystals.

The effects of cellulose nanocrystals (CNCs) (12, 24, and 36% w/w) on the microstructure and mechanical and thermal properties of canola protein isolate films were evaluated. The incorporation of cellulose nanocrystals led to homogeneous films, and new Fourier transform infrared peaks appeared at 1055 cm–1, indicating the presence and the interaction of CNCs with proteins and glycerol. The addition of CNCs also improved the thermal stability of the films, since higher temperatures were required for their thermal decomposition. In addition, CNC addition resulted in an increase in tensile strength and a decrease in elongation at break values due to strong interactions between the OH groups in proteins, glycerol, and CNCs.

Rheological and Microstructural Characteristics of Canola Protein Isolate-Chitosan Complex Coacervates.

Wastage of byproducts such as canola meal is a pressing environmental concern, and canola protein isolate (CPI)-chitosan (Ch) coacervates have a good potential to utilize and convert the wastes into a high value added product. Yet so far, there is very limited rheological and microstructural information to assist in proper utilization of CPI -Ch complex coacervates. The rheological and microstructural properties of the complex coacervates formed from CPI and chitosan Ch at various CPI-to-Ch mixing ratios (1:1, 16:1, 20:1, and 30:1) and pH values (5.0, 6.0, and 7.0) were therefore investigated. These CPI-Ch complex coacervate phases were found to exhibit elastic behavior as evidenced by significantly higher elastic modulus (G') compared to viscous modulus (G″) in all the tested ratios and pH ranges. They also exhibited shear-thinning behavior during viscous flow. The complex coacervates formed at the optimum CPI-to-Ch ratio of 16:1 and pH of 6.0 demonstrated the highest G', G″, and shear viscosity, which correlated well with the high strength of electrostatic interaction and thick-walled, sponge-like, less-porous microstructure at this condition. The higher shear viscosity of the coacervate at pH 6.0 was most likely induced by stronger attractive electrostatic interactions between CPI and Ch molecules, due to the formation of a rather densely packed complex coacervate structure. Hence, it can be concluded that the microstructural observations of denser structure correlated well with the rheological findings of stronger intermolecular bonds at the optimum CPI-to-Ch ratio of 16:1 and pH of 6.0. The complex coacervate phase formed at a CPI-to-Ch ratio of 16:1 and pH of 6.0 also showed glassy consistency at low temperatures and rubbery consistency above its glass-transition temperature. This study identified the potential for the newly developed CPI-Ch complex coacervate to be used as an encapsulating material due to its favorable strength. This would drastically reduce the wastage of byproducts, provide a solution to tackle the pressing global issue of wastage of byproducts, and bring about a more environmentally friendly paradigm.

Effect of high-intensity ultrasound on the compositional, physicochemical, biochemical, functional and structural properties of canola (Brassica napus L.) protein isolate.

The objective of this study was to investigate the impacts of high-intensity ultrasound treatments on the compositional, physicochemical, biochemical, functional and structural properties of canola protein isolates (CPI). Aqueous canola protein suspensions were sonicated at 40 kHz for 15 min and 30 min. The moisture content, water activity, bulk density and the L* and a* color parameters of the CPI decreased due to the ultrasound; however, the in vitro protein digestibility was not modified by the treatment. Glutelin (57.18%) was the main protein fraction in the canola protein isolate. SDS-PAGE demonstrated that there were no changes in the protein electrophoretic patterns, thus indicating that sonication did not break the covalent bonds. However, the ultrasound treatment improved the protein solubility, oil absorption capacity and the emulsifying, gelation and foaming properties, but these improvements depended on the pH and ultrasound exposure time. Scanning electron microscopy revealed that the ultrasound treatment disrupted the microstructure of the CPI by exhibiting larger aggregates as a lyophilized powder. In addition, there was an increase in the surface hydrophobicity and a decrease in the size of the particles of the canola protein due to the ultrasound effects, which indicates a destruction of the particles or a dissociation of the protein aggregates in the canola protein dispersions. These results suggest that ultrasound treatment is a valuable tool for improving the characteristics of canola proteins for use in foods.

Structural properties of canola protein isolate-gum Arabic Maillard conjugate in an aqueous model system

We aimed to study the effect of conjugation with gum Arabic (GA) by Maillard reaction in aqueous solution on the structural properties of Canola protein isolate (CPI). First, the grafting of GA to CPI through Maillard reaction was confirmed by examination of the Fourier transform infrared spectra. The results showed that the thermal stability of CPI was remarkably improved by mixing or conjugating with GA. The evidence of particle size distribution determined by nanoparticles tracking analysis (NTA) confirmed that glycation can reduce the thermal aggregation and also nanoparticles of conjugate appear bigger than CPI. Furthermore, the tertiary structure of protein in conjugate changed with decreasing number of aromatic side-chains exposed in heating environment. The decrease in fluorescence intensity of conjugate was related to conformational changes due to presence of GA.

Preparation and characterization of cross-linked canola protein isolate films

Cross-linked canola protein isolate (CPI) films were prepared using a bisepoxide as a chain extender by wet cast followed by heat compression. By DSC measurements, it was verified that the cross-linking reaction took place in the CPI matrix and was completed in 10min at 90°C. FTIR analysis confirmed that the chain extenders were covalently bonded with CPI chains. The reaction led to the formation of a cross-linked architecture which was revealed by an increase in molecular weight of the modified CPI films. The newly formed chain architecture increased the thermostability of CPI as evaluated by TGA; furthermore, the thermostability increased with the increase in cross-linking degree of the modified CPI films. DMA results of the unmodified CPI film showed that microcosmic phase separation occurred between two major proteins, cruciferin and napin in CPI; however, the extent of phase separation decreased with the increase of chain extenders and finally disappeared because of the increased compatibility between cruciferin and napin. Elastomeric mechanical behavior was observed with the introduction of cross-linked architecture in the modified CPI films. At low humidity of 55%, the cross-linked CPI films showed an increase in tensile strength and a decrease in elongation at break. At high humidity of 98%, the increase in hydrophobicity of cross-linked CPI matrix resisted the decreasing tensile strength seen in unmodified films.

Preparation of branched canola protein isolate and effects of molecular architecture on solution flow properties

Two branched canola protein isolates (CPI) with different branching degree were prepared using bis-epoxide as a chain extender. It was found that the branching reaction may take place in any protein fraction in native CPI; furthermore, by increasing the amount of chain extender, more native protein chains in CPI were coupled to form branches. In the study of flow properties of native and branched CPI solutions, it was found that the apparent viscosities of two branched CPI remarkably increased compared to that of native CPI over all concentrations tested. At 22 °C and pH 7, native CPI solution showed slight shear thinning behavior with the increase of shear rate; however, shear thickening was observed at low shear rate for branched CPI. Furthermore, shear thickening was more pronounced with the increase of branching degree and concentration of branched CPI solution. Shear thinning behavior of native CPI became marked at pH 11; however, the shear thickening property of branched sample was weakened at high pH. The novel findings in flow properties of the branched CPI solution could be potentially applied in the food industry, such as increasing foaming property and gelling ability of food products.

Effect of glycosylation with gum Arabic by Maillard reaction in a liquid system on the emulsifying properties of canola protein isolate

In this research, the improvement of emulsifying properties of chemically modified canola protein isolate (CPI) with gum Arabic (GA) through Maillard reaction under natural pH at 90°C was investigated. The stability, rheology and morphology of oil-in-water emulsions stabilized by conjugate of two biopolymers were evaluated by determination of droplet size, emulsifying activity (EAI), emulsifying stability (ESI) and creaming indices. The conjugate-stabilized emulsion showed smaller mean droplet size and lower creaming index values which were more effective to stabilize the emulsion compared to CPI and mixture of two biopolymers especially if pH was near the isoelectric point of CPI or when emulsions heated from 30 to 90°C. Moreover, our results demonstrated that EAI, ESI and viscosity of emulsion for CPI-GA conjugate were significantly more than those of CPI-GA mixture and CPI. These results suggested that Maillard reaction could be one of the most promising approaches to improve emulsifying properties of CPI for food applications.

Nature of protein-protein interactions during the gelation of canola protein isolate networks

The nature of interactions involved during the gelation of a canola protein isolate was investigated using rheology and fractal imaging at neutral pH as a function of protein concentration (5.0–9.0% w/w). The onset of denaturation and the denaturation temperature by differential scanning calorimetry for canola protein isolate (CPI; 98.2% protein) was 78.6°C and 87.1°C, respectively. Rheological testing determined the gelation temperature (Tgel) to be ~87–90°C for all concentrations. The log % strain at break increased from 1.70 to 1.80 as CPI concentration increased from 5.0 to 7.0% (w/w). Rheological testing of CPI in the presence of destabilizing agents, NaCl (0.1 and 0.5M), urea (0.1, 0.5, 1 and 5M) and 2-β-mercaptoethanol (0.1 and 2%), was performed. Samples with NaCl and urea (0.1–1M) had similar temperature profiles and Tgel values to CPI alone whereas no gel was formed with the addition of 5M urea and 2-β-mercaptoethanol reduced the strength of the gel network. Fractal dimension and lacunarity was analyzed using CLSM imaging. The fractal dimension value for all CPI concentrations was ~1.5. The lacunarity of the gel decreased from 0.62 to 0.41 as the concentration of CPI increased from 5 to 7% (w/w). Mechanistic understanding of CPI aggregation and network formation will enable the food industry to better tailor food structure when CPI is present as ingredient.

Preparation of chemically modified canola protein isolate with gum Arabic by means of Maillard reaction under wet-heating conditions

The aim of this study was to produce covalently attached conjugate between canola protein isolate (CPI) and gum Arabic (GA) in aqueous solutions via the Maillard reaction at 90°C in a model system consisting of 2% CPI and 1, 2 or 4% GA. Upon decreasing of free amino group content in the glycosylated CPI to 72%, a new band near the loading end of sodium dodecyl sulfate-polyacrylamide gel electrophoresis and a shift of CPI peak in high performance size exclusion chromatography confirmed that the covalent attachment of CPI to GA was successful. The results of secondary structure analysis suggested that grafted CPI had decreased α-helix and β-sheet levels and increased random coils level. The solubility of CPI at isoelectric point was improved remarkably after grafting with GA. The optimal conjugation conditions chosen from the further experiments were 1% of GA, 90°C and reaction time 15min.

Optimisation of the complex coacervation between canola protein isolate and chitosan

The complex coacervation phenomenon between canola protein isolate (CPI) and chitosan (CS) was studied. CPI was extracted in the laboratory from canola meal and used in this study. The factors affecting the yield of CPI-chitosan complex coacervates such as CPI-to-chitosan ratio, pH and strength of the electrostatic interaction (SEI) were investigated. The thermal characteristics of the un-cross-linked and transglutaminase cross-linked complex coacervates were also determined. The optimum complex coacervation between CPI and CS occurred at the CPI-to-chitosan mass ratio of 16 and the pH range of 5.8–6.2. The peak denaturation temperature and the denaturation enthalpy of CPI in CPI-chitosan complex were higher than those of the uncompleted or free CPI indicating that the complexation made the CPI more thermally stable. The thermal stability of the coacervates was further enhanced when cross-linked with transglutaminase. The increased thermal stability of CPI in CPI-chitosan coacervate indicated that CPI-chitosan coacervates would be suitable for encapsulation of thermally sensitive food and pharmaceutical ingredients.

Dispersion stability of non-refined turnip rapeseed (Brassica rapa) protein concentrate: Impact of thermal, mechanical and enzymatic treatments

Aqueous dispersion properties of a protein concentrate obtained from turnip rapeseed (Brassica rapa) press cake were investigated. Protein content of the press cake was enriched from 35.9% to 45.8% by sequential supercritical-CO2 extraction, milling and air classification. The protein denaturation degree and the solubility in the prepared protein concentrate were compared with a commercial canola protein isolate. Partial loss of the protein native structure was observed in the protein concentrate. The ζ-potential in the soluble fraction of the protein concentrate dispersion was ca. 20mV lower (more negative) compared with the commercial isolate at pHs 4–10, which was attributed to the presence of charged carbohydrates such as pectin in the protein concentrate. To improve the dispersion stability of the protein concentrate, enzymatic crosslinking with transglutaminase and microfluidization at 1850 bars were applied. Microfluidization resulted in the formation of rod-like aggregates formed mainly of the insoluble cell wall polysaccharides glued together with proteins as imaged by confocal laser scanning microscopy. Improvement in colloidal stability was observed in all samples upon microfluidization. Pre-treatment with transglutaminase resulted in different distributions of the components in the rods and further improved dispersion stability against sedimentation. Heat treatment caused compaction of the structures.

The effect of pH on the gelling behaviour of canola and soy protein isolates

The present study investigates the gelation mechanisms of a canola protein isolate (CPI) as a function of a pH (3.0–9.0), and compares it to that of a commercial soy protein isolate (SPI). A rheological investigation found that CPI was non-gelling at pH3.0, and then formed a gel with increasing strength as pH was raised from pH5.0 to 9.0. In contrast, the commercial SPI ingredient was found to be non-gelling at pH9.0, but formed the strongest networks at pH5.0 near its isoelectric point (pI=4.6). Denaturation temperature as determined by differential scanning calorimetry were found to occur at ~78°C for CPI at pH5.0, then shifted to higher temperatures (~87°C) at pH7.0/9.0, whereas detection of SPI denaturation could not be obtained due to instrument sensitivity. Gelling temperatures were similar for both CPI and SPI (~82–86°C) at all pHs, with the exception of SPI at pH5.0 (~46°C). Overall CPI networks were stronger than SPI, since the latter had weaker inter- and intramolecular junction zones. Confocal laser scanning microscopy images indicated that CPI gels became denser with lower lacunarity values as pH increased from 3.0 to 9.0. Moreover, the fractal dimension of CPI gels was found to increase from ~1.5-1.6 to ~1.8 as pH increased from 5.0/7.0 to 9.0, respectively suggesting diffusion-limited cluster-cluster aggregation. Images of SPI networks were not concurrent with fractal analysis under the conditions examined. Despite CPI having excellent gelling properties that are comparable to SPI, its need for alkaline pH conditions will limit its applicability in foods.

Study of the functional properties of canola protein concentrates and isolates extracted by electro-activated solutions as non-invasive extraction method

Abstract This study compared the functional properties of canola protein isolates and concentrates produced by electro-activated solutions and conventional alkaline extraction. In the case of the isolates, the results showed no significant difference in terms of protein solubility, surface hydrophobicity, water absorption and fat absorption capacity. However, for the protein concentrates, higher fat absorption capacity was observed for the proteins extracted by electro-activated solutions. Moreover, some surface active properties were also enhanced, notably higher emulsion activity index and smaller droplet size were observed for the proteins extracted by the electro-activation method. In all cases, the functional properties were strongly dependent on the pH of the medium and the behavior of the isolates and concentrates was quite different in the pH range close to isoelectric point, in neutral and alkaline regions. For all the functionalities, generally the results showed that the concentrates were more effective at pH 4, whereas isolates performed better at pH 7 and pH 9.