Canola Protein Research Articles

A Pursuit of the Functional Nutritional and Bioactive Properties of Canola Proteins and Peptides

This review focuses on updated information about canola proteins and peptides, their functional, nutritional, and bioactive properties, safety aspects, and potential application in foods. Attention is paid to gelation, emulsion, thermal, and water holding capacities of crude and pure proteins and peptides isolated from canola meal. Various factors affecting these properties are discussed. This paper provides an overview of use of canola meal as a protein source in animal diets and their digestibility in vivo. Their effects on a range of health outcomes including ACE inhibition, hypocholesterolemic effects, cancer prevention, anti-viral and anti-diabetic properties are reviewed on the basis of the available in vitro and in vivo animal and human data. The review also focuses on the safety aspects and selected food applications of canola proteins and peptides.

Impact of Antinutritional Factors in Food Proteins on the Digestibility of Protein and the Bioavailability of Amino Acids and on Protein Quality

Dietary antinutritional factors have been reported to adversely affect the digestibility of protein, bioavailability of amino acids and protein quality of foods. Published data on these negative effects of major dietary antinutritional factors are summarized in this manuscript. Digestibility and the quality of mixed diets in developing countries are considerably lower than of those in developed regions. For example, the digestibility of protein in traditional diets from developing countries such as India, Guatemala and Brazil is considerably lower compared to that of protein in typical North American diets (54-78 versus 88-94 %). Poor digestibility of protein in the diets of developing countries, which are based on less refined cereals and grain legumes as major sources of protein, is due to the presence of less digestible protein fractions, high levels of insoluble fibre, and/or high concentrations of antinutritional factors present endogenously or formed during processing. Examples of naturally occurring antinutritional factors include glucosinolates in mustard and canola protein products, trypsin inhibitors and haemagglutinins in legumes, tannins in legumes and cereals, gossypol in cottonseed protein products, and uricogenic nucleobases in yeast protein products. Heat/alkaline treatments of protein products may yield Maillard reaction compounds, oxidized forms of sulphur amino acids, D-amino acids and lysinoalanine (LAL, an unnatural nephrotoxic amino acid derivative). Among common food and feed protein products, soyabeans are the most concentrated source of trypsin inhibitors. The presence of high levels of dietary trypsin inhibitors from soyabeans, kidney beans or other grain legumes have been reported to cause substantial reductions in protein and amino acid digestibility (up to 50 %) and protein quality (up to 100 %) in rats and/or pigs. Similarly, the presence of high levels of tannins in sorghum and other cereals, fababean and other grain legumes can cause significant reductions (up to 23 %) in protein and amino acid digestibility in rats, poultry, and pigs. Normally encountered levels of phytates in cereals and legumes can reduce protein and amino acid digestibility by up to 10 %. D-amino acids and LAL formed during alkaline/heat treatment of lactalbumin, casein, soya protein or wheat protein are poorly digestible (less than 40 %), and their presence can reduce protein digestibility by up to 28 % in rats and pigs, and can cause a drastic reduction (100 %) in protein quality, as measured by rat growth methods. The adverse effects of antinutritional factors on protein digestibility and protein quality have been reported to be more pronounced in elderly rats (20-months old) compared to young (5-weeks old) rats, suggesting the use of old rats as a model for assessing the protein digestibility of products intended for the elderly.

Optimizing plant protein combinations in fish meal-free diets for rainbow trout (Oncorhynchus mykiss) by a mixture model

The aim of this experiment was to define the optimal mixtures of plant protein concentrates in an extruded, fish meal free diet for rainbow trout. Three essential amino acids (EAA) and taurine-fortified plant protein mixtures (P-MIX, C-MIX, and S-MIX) were prepared by mixing four plant protein concentrates (pea protein concentrate (PPC), canola protein concentrate (CPC), potato protein concentrate, and soy protein concentrate (SPC)). Seven plant protein based diets were formulated based on a mixture design using P-MIX, C-MIX, and S-MIX alone (the PPC, CPC or SPC diets) or in combinations (the P+C, P+S, C+S, P+C+S diets) to provide >95% of the dietary protein. The diets were supplemented with 5% krill products as attractant. One fish meal based diet, which acted as a reference diet, used LT-fish meal as the sole dietary protein source (FM diet). All diets were tentatively balanced to contain equal amounts of digestible protein (400gkg−1) and digestible energy (21MJkg−1). Each diet was fed to two tanks of 61g rainbow trout reared in 9°C water for 72days. No significant differences (P>0.05) were seen in weight gain. Dietary plant protein treatments that gave significantly higher values than the FM diets were: feed intake for the CPC and SPC diets; feed conversion ratio (FCR) for all diets, except for P+C and P+C+S; apparent digestibility (AD) of phosphorus (P) for all diets; AD of Arg and Met for the SPC diet; whole body crude protein content for the SPC and P+S diets; retention of dietary P intake for all diets, except for the SPC and P+S diets; N intake, metabolic N loss and energy intake per kg gain for all diets; nitrogen (N) retained in growth per kg gain for the SPC and P+S diets; fecal N loss per kg gain for the CPC diet; fecal energy loss per kg gain for the PPC, CPC, SPC and C+S diets. Significantly lower values than the FM diets were obtained for: AD of N for the CPC diet; AD of lipid for the SPC diet; AD of energy for the CPC, SPC, and C+S diets; AD of all EAA, Cys, and total amino acids for the CPC diet; retention of dietary and digestible N intake for all diets; dietary energy intake per kg gain for the CPC, SPC and C+S diets; P intake and fecal P excretion per kg gain for all diets. Using the combination of P-MIX and C-MIX resulted in the highest retention of digestible N. A combination of P-MIX and C-MIX led to the most efficient feed conversion. AD of N and individual amino acids were highest when S-MIX was used alone. The most efficient AD of lipid and energy were obtained by a combination of P-MIX and S-MIX. Using C-MIX alone supported the highest AD and retention of P, and whole-body concentrations of ash, P, Ca and Mg, due to CPC being dephytinized. Retention of dietary N was most efficient when a combination of P-MIX and S-MIX was used, while retention of digestible N was most efficient for a combination of P-MIX and C-MIX. In conclusion, the mixture model proved useful for optimizing combinations of plant protein concentrates in a fish meal-free diet for rainbow trout.

Effects of Sodium Bisulfite on the Physicochemical and Adhesion Properties of Canola Protein Fractions

This study focused on investigating the potential of using canola protein fractions as bio-degradable wood adhesives. Native and sodium bisulfite (NaHSO3)-modified canola protein fractions isolated successively at different pH values (7.0, 5.5, and 3.5) was used as adhesives. Wood specimens were assembled with adhesives at a pressure of 2 MPa at 150, 170, or 190 °C for 10 min. The adhesion performance of adhesives were evaluated by wet, soak, and dry shear strength. Their physicochemical properties: extractability, electrophoresis profiles, thermal, rheological and morphological properties were also characterized. Results showed that canola protein had the highest protein yield and purity at pH 5.5. Electrophoresis profile proved that NaHSO3 cleaved the disulfide bonds in canola protein. This could induce extra charges (RS-SO3 −) on the protein surface, leading to the reduced apparent viscosity. Thermal analysis implied that the thermal transition temperature of canola protein decreased with modification of NaHSO3. Canola protein adhesives showed excellent dry and soak shear strength with 100 % wood cohesive failure in all curing temperatures. The wet adhesion strength of native and modified canola protein fraction adhesives at pH 5.5 and pH 3.5 (3.9–4.1 MPa) was higher than the fractions at pH 7.0. NaHSO3 had insignificant effects on the adhesion performance of canola protein adhesives but notably improved the handling and flow-ability properties of canola protein adhesives.

The effect of increasing inclusion rates of soybean, pea and canola meals and their protein concentrates on the growth of rainbow trout: Concepts in diet formulation and experimental design for ingredient evaluation

A series of six growth experiments were conducted to assess the effects of feeding pea meal (PM), pea protein concentrate (PPC), soybean meal (SBM), soy protein concentrate (SPC), canola meal (CM) and canola protein concentrate (CPC) on the growth of rainbow trout. The nutrient digestibility of the experimental ingredients was determined prior to commencement of this experiment. Based on these digestibility values, diets containing 0, 75, 150, 225 or 300g/kg of each test ingredient were formulated. All diets contained 17.6MJ/kg digestible energy, 386.2g/kg digestible crude protein and were balanced for digestible essential amino acids to meet or exceed the requirements of rainbow trout. The inclusion of fish meal in the diets was kept as constant as possible within the constraints of balancing digestible nutrients. Experiments for each ingredient were conducted consecutively over a 361-day period. During each growth experiment, three tanks of rainbow trout per treatment were fed twice daily to apparent satiety for 56days. Fish were weighed on days 0 and 56 and total feed intake was measured. Linear and quadratic regression equations of the growth parameters on ingredient inclusion rate were calculated. The calculated regression equations for inclusion rate on average daily feed intake (ADFI), specific growth rate (SGR), feed conversion ratio (FCR) and protein efficiency ratio (PER) were not significant for PM, SPC or CPC (P>0.05). PPC inclusion had a positive linear relationship with ADFI (P<0.05). SBM inclusion had a significantly negative quadratic relationship with SGR and FCR, while for PER, both the linear and quadratic regressions were negative (P<0.05). CM inclusion rate had a significantly negative linear and quadratic relationship with specific growth rate and feed conversion ratio. The P-value for the linear regression was lower than for the quadratic regression. CM also had a negative linear relationship with PER (P<0.05). The results suggest there are no significant negative ingredient effects of PM, PPC, SPC and CPC on rainbow trout growth. Thus, growth can be predicted on the basis of digestible nutrients for these ingredients, provided the nutritional standards set for this experiment are followed. SBM and CM have significantly negative ingredient effects, which must be taken into account when using these ingredients in rainbow trout diets.

Impact of Meal Preparation Method and Extraction Procedure on Canola Protein Yield and Properties

Screw-pressed and cold-milled, solvent-defatted canola meal was processed with a conventional Osborne sequence extraction method to obtain albumin, globulin, prolamin, and glutelin protein fractions. This extraction sequence was altered by isolating globulins prior to albumins, resulting in an increased globulin yield. The difference can be attributed to the presence of salts in canola meal flour, which increase globulin extraction during albumin isolation in the conventional method. An increase in the cumulative protein yield was observed when cold-milled canola meal flour was used instead of screw-pressed flour. Significant differences were also observed in the functional properties (water absorption, fat absorption, and emulsifying activity) of canola protein fractions with respect to both meal preparation method and protein isolation method. Results suggested that milling temperature and isolation method can have significant impacts on protein quality and yield.

Toxicological studies on plant proteins: a review

Nowadays, toxicological studies are contributing to human health more than ever. Reports on the toxicological studies of plant proteins, which are continuously growing in number in the literature, have been reviewed. Two important aspects are discussed: dietary safety evaluation, including toxicity tests and the maximum daily intake allowance, and the appropriate proportion in our daily diets of proteins from traditional foods and of new proteins from plant sources not traditionally employed as foods. Water hyacinth leaf proteins, sweet lupin proteins and canola proteins have not been shown to be toxic, although they are not traditionally employed as food proteins. These findings are very important for exploiting valuable new protein sources that are suitable for human or animal consumption and applicable to the food industry. Acutely toxic proteins, including lectins, ribosome-inactivating proteins, inhibitors of proteolytic enzymes and glycohydro-lases, have been isolated from plant materials and identified. Their toxicities and molecular characteristics have been described. The toxicity of proteins depends upon their specific native structures. Once they are denatured by appropriate treatment, such as heating, their toxicity can be reduced or even eliminated. These findings indicate that raw materials that contain this kind of toxic protein are not edible. However, after proper processing, they may be suitable for human or animal consumption. Although the toxicities of type 2 ribosome-inactivating proteins reported by different authors vary, the maximum dosages are still trace amounts.

Physicochemical Properties and Adhesion Performance of Canola Protein Modified with Sodium Bisulfite

AbstractThe objective of this research was to study the adhesion properties of sodium bisulfite (NaHSO3)‐modified canola protein. Protein was extracted from canola meal through alkali solubilization and acid precipitation methods, then modified with different concentrations of NaHSO3 (0–15 g/L) during the isolation process. As NaHSO3 concentration increased, canola protein purities decreased. Amino acid profiles showed that the hydrophobic amino acids in canola protein constituted only 27% of total protein, indicating that canola protein is mostly hydrophilic. The reducing effects of NaHSO3 were exerted on canola protein through the breaking of disulfide bonds in both its cruciferin and napin components, as reflected by the protein electrophoresis profile, DSC data, and morphological images. The wet protein isolates were used as adhesives. The greatest wet shear strength of canola protein adhesive without modification was 3.97 MPa with 100% wood cohesive failure (WCF), observed at a curing temperature of 190 °C. NaHSO3 had slight weakening effects on the adhesion performance of canola protein. Canola protein modified with 3 g/L NaHSO3 exhibited wet shear strength similar to the control at 190 °C and higher strength at 150 and 170 °C. The NaHSO3 modification significantly improved handling and flowability of canola protein adhesives.

Effect of Canola Protein Extraction Parameters on Protein-Based Plastic Properties

Effect of Canola Protein Extraction Parameters on Protein-Based Plastic Properties

Partial Replacement of Fish Meal with Plant Protein Sources Singly and in Combination in Diets for Summer Flounder, Paralichthys dentatus

Soybean meal (SBM), corn gluten meal (CGM), and canola protein concentrate (CPC) as alternative protein sources to fish meal (FM) were individually evaluated for growth performance at 0, 20, 30, 40, and 50% replacement with amino acid (AA) supplementation using juvenile summer flounder, Paralichthys dentatus, in an 8‐wk feeding. Two‐way ANOVA indicated no significant main effect for plant protein source, but a significant main effect for replacement level. Comparison of the individual treatments revealed significant differences in weight gain (WG) between the FM treatment and 50% replacement level for all protein sources, as well as between the FM treatment and 30% replacement with CPC. Replacement of FM with SBM at 40% resulted in the least cost/kg WG. In a follow‐up study, a combination of SBM–CGM–CPC at 40% replacement was evaluated with and without AA, phytase (0.2%), or taurine (1%), versus FM and SBM (40% replacement of FM) with AA. The SBM–CGM–CPC diet with either AA or taurine provided a significantly better food conversion ratio and less cost/kg WG than the SBM diet, and the SBM–CGM–CPC diet with taurine provided a significantly better protein efficiency ratio than the SBM diet. On the basis of these results, more study of taurine in plant protein diets for summer flounder appears warranted.

Nutritional Evaluation of Canola Protein Concentrate for Broiler Chickens

This trial was conducted to determine the effects of including canola protein concentrate in diets fed to broiler chickens on nutrient digestibility and broiler performance (0-21 days). A total of 180, day-old, male broiler chicks weighing an average of 52.80.6 g were assigned to one of six dietary treatments in a completely randomized design. The control diet was based on corn and soybean meal and contained 15% canola meal. The experimental diets contained 3, 6, 9, 12 or 15% canola protein concentrate added at the expense of canola meal. There were five birds per pen and six replicate pens per treatment. Feed and water were available ad libitum throughout the 21-day experiment. Chromic oxide (0.35%) was added to all diets as a digestibility marker and was fed throughout the experimental period. The digestibility of dry matter, energy and phosphorus increased linearly (p

Effect of sieve size on chemical composition and functional properties of canola meal ( Brasscia napus ) protein fractions as fishmeal replacement

Canola meal (CM) use in animal nutrition is limited due to the inclusion of various antinutritional factors (ANF). This study aimed to evaluate the effect of sieving on nutrient and ANF contents of CM. Five sieves with mesh size (diameter) of 16, 18, 20, 30 and 40 were used in this regard. With an increase in the mesh size, the recovery percentage significantly decreased (73.7 vs. 18.3), while crude protein content (370.7 vs. 378.1 g/kg), gross cost (0.47 vs. 1.91 US$/kg) and protein unit cost (1.27 vs. 1.66 US$/kg) were significantly increased (P < 0.05). In the next stage, only the sieved canola meal obtained through mesh size 16, 18 and 20 was selected for further investigation. The amounts of crude protein, crude fat and total NSP of the processed products were not significantly differed. However, the amounts of acid detergent fiber (218.2 g/kg vs. 206.7 g/kg) and neutral detergent fiber (330.8 g/kg vs. 319.1 g/Kg) significantly decreased by increasing mesh size. Glucosinolates (20.67 vs. 21.82 μmol/g DM) and phytate (40.6 g/kg vs. 62.0 g/kg) had significant increment (P < 0.05) on the other hand. Considering the weighted averages of different measured variables from PCA, the mesh size 16 was selected for use in the production of a canola protein concentrate.

Properties of Canola Protein‐based Plastics and Protein Isolates Modified Using SDS and SDBS

AbstractCanola protein isolates were prepared from canola meal flour using alkaline solubilization and acid precipitation. The isolates were treated with sodium dodecyl sulfate (SDS) and sodium dodecyl benzene sulfonate (SDBS) with concentrations between 1 and 5%. Functional property analysis of modified isolates revealed that water absorption and fat absorption increased by up to 115 and 78%, respectively, with increasing SDBS concentrations. Fat absorption of SDS‐modified isolates showed a similar trend to that of SDBS‐modified isolates (86% increase), but water absorption decreased (by 77%) in the 5% SDS treatment. SDS and SDBS treatments reduced the emulsifying activity of protein isolates by 34 and 30%, respectively. The denaturation effect of SDS and SDBS treatments increased the surface hydrophobicity of proteins and resulted in increased tensile strength (by 14 and 41%), tensile modulus (by 31 and 52%), and toughness (by 44 and 64%) of plastic specimens prepared using modified isolates. Only the 3% treatments of SDS and SDBS increased the elongation of plastics (by 22 and 11%, respectively) while other treatments did not show significant differences from the plastics that used non‐modified isolates. The water absorption of plastics increased by 33% with the 5% SDS treatment; the SDBS treatments showed a 9% decrease in water absorption for the 1% treatment but no significant differences at higher concentrations. Denaturation by SDS and SDBS can be employed to alter functional properties of canola protein isolates as well as the mechanical properties of canola protein‐based plastics.

In vitro pH-Stat protein hydrolysis of feed ingredients for Atlantic cod, Gadus morhua. 2. In vitro protein digestibility of common and alternative feed ingredients

Using enzyme fractions isolated from the pyloric caeca of farmed Atlantic cod, the in vitro degree of protein hydrolysis (DH) of numerous conventional and novel feed ingredients were measured by a closed-system pH-Stat assay. Regression equations describing the relationship between in vivo apparent protein digestibility (ADC) and in vitro protein DH were used to predict in vitro protein ADC. The equations resulted in good correlation (< 4 percentage points difference) between ‘measured’ and ‘predicted’ protein ADC in the majority of cases ( r = 0.90-0.99; R 2 = 0.88-0.99), while some ingredients were either over- or under-estimated (6–7 percentage points) which appears related to high ash or chitin content ( r = 0.75; R 2 = 0.61) and may indicate the need for an acid pre-hydrolysis phase and full account of non-protein nitrogen (NPN) content. The ‘predicted’ in vitro protein ADC were above 95% for wheat gluten meal, soy protein concentrate, soy protein isolate and whole krill meal; relatively high (85-95%) for soybean meal, white lupin meal, herring meal, anchovy meal, canola protein concentrate, pea protein concentrate and poultry by-product meal; mid-range (75-85%) for crab meal, shrimp meal and canola meal; and low (< 75%) for hydrolyzed feather meal and flaxseed meal. Further research is needed on the development of a two-stage hydrolysis assay for gadoids involving an acid (gastric) pre-digestion step prior to this assay to further increase agreement between in vivo protein ADC and in vitro protein DH.

Production Performance and Stress Tolerance of Sunshine Bass Raised on Reduced Fish Meal Feeds Containing Ethanol Yeast

AbstractEthanol yeast (EY) has been shown to be an effective alternative to fish meal (FM) in diets of sunshine bass (female white bass Morone chrysops × male striped bass M. saxatilis). Diets containing blends of FM and EY yield production performance similar or superior to that of diets containing no EY. Complete replacement of FM with EY, however, reduces feed palatability, impairs production performance, and may affect other aspects of livestock vigor. Accordingly, the objectives of this study were to determine the effects of dietary EY inclusion (with or without a palatant) on the feed intake, growth performance, and physiological robustness of sunshine bass after stressor exposure. Formulations were developed containing 15, 7.5, and 0% FM with EY as the primary alternative protein source. Experimental diets were prepared according to these formulations with and without the addition of 1% soluble canola protein concentrate as a palatant. Replicate tanks of juvenile sunshine bass (∼4.4 g) were fed the experimental feeds twice daily to apparent satiation for 9 weeks. Production performance was assessed, and then the fish were subjected to a 2‐min net‐chasing stress challenge protocol. Tissue samples were collected to allow for the determination of organosomatic indices and pre‐ and postchallenge hematology. Complete replacement of FM with EY resulted in reduced growth performance and efficiency and significantly altered whole‐body proximate composition, reducing carcass protein and increasing carcass lipid. Palatant inclusion had no effect on diet acceptance or production performance. Plasma glucose and lysozyme activity were significantly affected by stress; however, dietary treatment did not affect these parameters. While cortisol levels were marginally higher among stressed fish, they were higher than expected in unstressed fish. Our results confirm previous research suggesting that the optimal level of FM in EY‐based sunshine bass feed is between 7.5% and 15%. Further research is needed to fully understand the utilization of these feeds and their effects on the physiological status of sunshine bass.Received July 13, 2010; accepted October 1, 2010

Effects of Protein Separation Conditions on the Functional and Thermal Properties of Canola Protein Isolates

Canola meal protein isolates were prepared from defatted canola meal flour using alkaline solubilization and acid precipitation. A central composite design was used to model 2nd-order response surfaces for the protein yield and the functional properties of protein isolates. The solubilization pH and precipitation pH were used as design factors. The models showed that the protein yield and functional properties of isolates, such as water absorption and fat absorption, were sensitive to both solubilization pH and precipitation pH, whereas the emulsification was sensitive to only solubilization pH. Gel electrophoresis analysis of protein fractions gave evidence to the compositional changes between proteins isolated under different conditions. Differences in glass transition temperatures suggest that proteins tend to be more denatured when solubilized at highly alkaline conditions. These conformational and compositional changes due to different protein separation conditions have contributed to the changes in functional properties of protein isolates. Protein isolation conditions may be determined primarily through optimization of total protein yield. Improvements in protein functional properties may be achieved with a relatively small sacrifice in yield by altering isolation conditions.

Extraction and characterization of protein fractions from Australian canola meals

Canola proteins were sequentially extracted from four Australian canola meals of different species and two industrial meal samples, according to Osborne method (OSB), based on their solubilities in water, 5% NaCl, 0.1 M NaOH and 70% ethanol respectively. These extracts were then compared to the glutelin fraction obtained by direct alkaline extraction method (DIR) in terms of protein yield, recovery, electrophoretic profile, and residual antinutritional components. The OSB method was found to be more effective for protein extraction which resulted in higher cumulative protein yield and recovery of water-soluble protein fractions, although the DIR method produced a glutelin fraction of higher protein content. Phenolic compounds were observed in all the extracted protein fractions although sinapine, the major phenolic compound in canola, was present only in the albumin fractions. The glucosinolate content of all extracts was below the detection limit of the method employed (< 3 μmol/g). While the electrophoretic profiles of all four OSB fractions were largely different, the DIR fraction was very similar to the glutelins obtained from the OSB method. Isoelectric focusing revealed that many of the proteins in the canola varieties ranged in pI between pH4.6 and 8.3.

Canola proteins for human consumption: extraction, profile, and functional properties.

Canola protein isolate has been suggested as an alternative to other proteins for human food use due to a balanced amino acid profile and potential functional properties such as emulsifying, foaming, and gelling abilities. This is, therefore, a review of the studies on the utilization of canola protein in human food, comprising the extraction processes for protein isolates and fractions, the molecular character of the extracted proteins, as well as their food functional properties. A majority of studies were based on proteins extracted from the meal using alkaline solution, presumably due to its high nitrogen yield, followed by those utilizing salt extraction combined with ultrafiltration. Characteristics of canola and its predecessor rapeseed protein fractions such as nitrogen yield, molecular weight profile, isoelectric point, solubility, and thermal properties have been reported and were found to be largely related to the extraction methods. However, very little research has been carried out on the hydrophobicity and structure profiles of the protein extracts that are highly relevant to a proper understanding of food functional properties. Alkaline extracts were generally not very suitable as functional ingredients and contradictory results about many of the measured properties of canola proteins, especially their emulsification tendencies, have also been documented. Further research into improved extraction methods is recommended, as is a more systematic approach to the measurement of desired food functional properties for valid comparison between studies.

Associative phase separation involving canola protein isolate with both sulphated and carboxylated polysaccharides

Associative phase separation within admixtures of canola protein isolate (CPI) and anionic polysaccharides (alginate and ι-carrageenan) was investigated as a function of pH (1.50–7.00) and biopolymer weight mixing ratio (1:1–50:1, w/w) by turbidimetric analysis. Solubility of formed complexes was also studied vs. protein alone as a function of pH. 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 to a 20:1 CPI–polysaccharide ratio, and then became constant. Complexes formed primarily through electrostatic attractive forces with secondary stabilisation by hydrogen bonding. Solubility of the CPI–alginate system was significantly enhanced relative to CPI alone or CPI–ι-carrageenan.

Plastics from an Improved Canola Protein Isolate: Preparation and Properties

AbstractCanola 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 (&gt;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.