Canola protein

Functional properties of canola protein products can be improved by succinylation (130,131). Controlled acetylation can reduce undesirable phenoHc constituents as well (132). However, antinutrients in canola and other vegetable protein products such as glucosinolates, phytic acid, and phenoHc compounds have severely limited food appHcations of these products. 

Table n. Canola Protein in solution and Mean Particle Size for Various... 

Experiments were performed to determine the optimum pH for the extraction of proteins from the industrially defatted canola meal (Federated Co-op Ltd., Saskatoon, SK) and sunflower meal (Cargill Inc., West Fargo, ND), and the minimum solubility pH (isoelectric pH) for precipitation. Details of the experimental methods can be found in (7) and (13) respectively. The extracted protein solutions were then used to recover proteins by precipitation. Four different types of precipitants aqueous HCl, HMP, CMC, and ammonium sulphate, were used for studies on the yields of canola protein. Further studies on isoelectric precipitation (using aqueous HCl as a precipitant) were carried out in three types of precipitators (Batch, MSMPR, and tubular) to study kinetic parameters and effects of precipitator type and operating conditions on PSD. The first two types of precipitators were used for canola protein and all three types were used for sunflower protein. Details of these experimental setups can be found in (7) for canola protein and (13,11) for sunflower protein. 

Figures 6 and 7 present the solids yield for canola and sunflower proteins during isoelectric precipitations, respectively. Sunflower protein yields from the flow-type precipitators increased with increases in mean residence times. This means that slower processes of particle growth by aggregation and diffusion follow an initial rapid nucleation process. About two minutes are required before the final yield is reached according to the results obtained from the tubular precipitator operating in the laminar flow regime and the batch precipitator. For canola proteins, mns in an MSMPR precipitator showed little changes in the yield with the mean residence time. This is because the mean residence times were longer (between 1.5 and 7.5 min) allowing the reaction to go to completion.

Figure 6. The effect of precipitation time on the total protein yield and mean particle particle size for precipitation of canola protein in an MSMPRP (pH = 4.2, S = 0.0581-0.623, IS = 0.025 ml NaCl/L, impeller speed = 304 rpm). x = Yield, A = Mean particle size 10).

Paulson, A.T. Tung, M.A. Solubility, hydrophobicity and net charge of succinylated canola protein isolate. J. Food Sci. 1987, 52, 1557-1561. 

Although PLS regression includes all of the wavelengths in an array, most of the variance used in computation of a PLS model will be in the vicinity of the wavelengths selected by MLR (107). In the case of the predictions of water in maize and oil in canola, protein bands were important in the respective models, and the protein bands selected for the wheat and lentil models were all small bands. There is a strong negative correlation between oil and protein contents in canola (r = 0.85 — 0.90), which could account for the presence of a protein band in the canola oil model. 

The proximate composition of canola/rapeseed varies among varieties as a result of both genetic makeup and growing conditions. As summarized in Table 4.3 [4], the oil content of canola is about twice that of soyabeans and contains much more fibre than soyabeans. The protein content of oil-free canola meal is only slightly lower than that of soyabeans. Canola is processed primarily for its oil, which makes up some 40% of the seed mass. It has an ideal fatty acid composition for human consumption, with a linoleic-to-linolenic acid ratio of approximately 2. After oil removal, the meal contains more than 40% protein with well-balanced amino acid composition. The essential amino acid composition, given in Table 4.4, indicates that canola protein is superior... 

Functional Properties of Canola Protein Products Water Water-Olding Fat Absorption Capacity Absorption Emulsifying Activity Overrun... 

Like soy proteins, extracted canola proteins were typically recovered by isoelectric precipitation. The precipitates, after being washed and dried, constitute the protein isolate. Due to the complex protein compositions and varietal differences among canola strains, a wide range of isoelectric points was observed, at each of which only a specific fraction of the extracted protein was precipitated, therefore protein recovery of single-step isoelectric precipitation was usually low. The highest ever reported was 65.7% of the amount of protein extracted at pH 11, obtained at pH 3.6 [32]. Moderate increase in protein yield was achieved by the same researchers with multi-isoelectric precipitation at different pH. Therefore, the further improvement in overall protein output hinges on the recovery of fractions that were not precipitated, and these proteins, due to their high solubility, are ideal for many food applications. 

Since canola proteins are large molecules with molecular weights >10,000, membrane technology was investigated as an effective means for their recovery. Ultraflltration uses semi-permeable membranes to selectively pass or retain solutes of interest, thus achieving isolation or concentration and purification. Woik in this area has been inspired by a wide variety of applications of manbrane technology in the food industry, especially the diary and soyabean sectors and the great strides in... 

So far, two processes involving membrane separation for canola protein isolation are considered promising, and both are currently under commercial development Researchers at the University of Toronto developed a membrane-based process for canola protein isolation from defatted meal [29,42], in which, after precipitation, the soluble proteins were ultraflltered to be concentrated and diaflltered for purification. Two protein isolates were produced precipitated and soluble, with a combined protein recovery of more than 70% of total meal protein. Both products were high in protein (>85%), low in phytates (<1%), essentially free of glucosinolates (<2 (xmol/g) and had desirable functional properties comparable to those of soy protein. While the methionine content of both protein isolates was similar to the reported values, the soluble product was found to have a higher level of lysine than any canola proteins obtained before, and the precipitated protein isolate was, on the other hand, farther enriched with leucine [43]. This amino acid composition makes them suitable for nse in infant formulae (Table 4.6). Despite their excellent nutritive quality. 

Essential Amino Acid Composition of Products of Membrane-Based Canola Protein Isolation (g/100 g Protein)... 

Source From Tzeng, Y. M. 1987. Process development for the production of high-quality rape-seed (canola) protein isolates using membrane technology. Ph.D. Thesis. University of Toronto, Toronto, Canada. With permission. 

FIGURE 4.8 Membrane-based process for canola protein isolation. (From Jones, J. D. and Holme, J. 1979. Oilseed processing. US Patent 4,158,656 Diosady, L. L., Xu, L. and Chen, B. K. 2005. Production of high-quality protein isolates from defatted meals of Brassica seeds. US Patent 6,905,713. With permission.)... 

Burcon NutraScience Corporation, a venture capital company founded at the turn of the century and specialized in the commercialization of canola proteins, adopted a unique process based on salt extraction [47], Saline of 0.15 M was used as the extractant. As shown in Figure 4.9, after extraction the resulting protein solution was concentrated by ultrafiltration to a concentration in excess of 200 g/L, and then diluted with chilled water at a temperature below 15°C to form a protein micellar mass (PMM), which accounted for 40-60% extracted protein, depending on the initial protein concentration and dilution ratio. PMM was settled, separated from supernatant and dried to obtain a protein isolate with a protein content over 100% (N X 6.25). The supernatant was processed to recover additional proteins by further... 

FIGURE 4.9 Buicon s process of canola protein isolation. (From Barker, L. D., Martens, R. W. and Murray, E. D. 2010. Prodnction of oil seed protein isolate. US Patent 7,687,087 B2. With permission.)... 

Ghodsvali, A., Haddad Khodaparast, M. H., Vosoughi, M. and Diosady, L. L. 2005. Preparation of canola protein materials using membrane technology and evaluation of meals functional properties. Food Res. Int. 38 223-231. 

Tzeng, Y. M., Diosady, L. L. and Rubin, L. J. 1990. Production of canola protein materials by alkaline, extraction, precipitation, and membrane processing. J. Food Sci. 55 1147-1151. 

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