Extraction, Characterization and Functional Studies of Australian Canola Proteins

While the electrophoretic profiles of all four OSB fractions were largely different, the CPI was similar to the glutelins obtained from the OSB method. Isoelectric focusing revealed that most proteins ranged in pI between pH 4.6 and 8.3. 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). Further study also revealed the presence of glucosinolate breakdown products in some of the OSB protein fractions, the content of which was significantly higher in the fractions extracted from non-canola grade meals in comparison to those prepared from canola grade meals which, in general, contained lower levels of residual antinutritional components.Technological functionalities of major canola proteins (albumin fraction, globulin fraction, and CPI) were investigated focusing on emulsifying and gelling properties. Comparisons were made with soy protein isolate (SPI), which is currently widely used in the food industry. Emulsion forming properties were studied via emulsifying capacity (EC), emulsifying activity index (EAI), and average droplet size at a range of pH from 4 to 9. The stability of emulsions formed was also studied, in terms of changes in particle size and physical attributes of the emulsions during storage. The globulin fraction had better emulsion forming properties compared to the albumin fraction and CPI in all the aspects analyzed regardless of the pH. In comparison to SPI, globulin fractions had higher EC at all pH values tested, higher EAI at acidic pH, and smaller or comparable average emulsion droplet size at both pH 4 and 7.