Learn how to improve physical, textural properties of canola protein isolate.

Mixtures of biopolymers contribute to the formation of gel networks in food systems. In order to effectively utilize these networks, we must understand the type and role of interactions involved in their formation. A better understanding of the factors responsible for enhancing the physical and textural properties of canola protein isolate (CPI) in food systems will provide a basis for value- added processing of canola meal, which is currently sold as an animal feed ingredient.

Scientists at the University of Manitoba found no published information on how molecular interactions are related to the structural arrangement of mixed gels that contain commercial canola protein. So, the researchers examined the structural ordering of canola protein isolate-k- carrageenan gels and the molecular forces that stabilize and strengthen network structure.

The microstructure of CPI, k-carrageenan (k-CAR) and CPI-k-CAR gels was assessed using scanning electron microscopy (SEM). After making some visual observations, the researchers obtained SEM images of each gel. The effects of pH, urea and dithiothreitol (DTT) on the network structure of CPI and CPI-k-CAR gels were evaluated.

Individual CPI gels showed varied structures at acidic and alkaline pH. At pH 6, the scientists observed loosely crosslinked protein networks with empty cells or holes that entrapped liquid components. But properly crosslinked network structures were obtained at pH 10. The network structures of individual CPI and k-CAR gels significantly improved when the two macromolecules were combined, indicating there is a synergistic behavior between CPI and k-CAR.

Urea and DTT affected the interactions involved in the formation of the network as well as the structural arrangement of CPI-k-CAR gels. Gels treated with urea were excessively crosslinked, showing a marked alteration of the gel structure. The systems treated with DTT had an amorphous structure. Results support the involvement of disulfide bonds and noncovalent interactions in the structural arrangement and strengthening of canola protein-k-carrageenan gels. Further information. Susan Arntfield, Department of Food Science, University of Manitoba, 201 Ellis Building, Winnipeg, MB, R3T 2N2 Canada; phone: [phone]; email: [e-mail].