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UBC Theses and Dissertations

Functional properties of modified oilseed protein concentrates and isolates Jones, Linda Jean


Compositional, structural and functional properties of nine oilseed concentrates and isolates were evaluated and compared. Three product sources, canola (rapeseed), sunflower and soybean were investigated, each treated during processing by enzyme-hydrolysis or linoleic acid addition, or left untreated as controls. Protein, carbohydrate and moisture contents of the products were measured, and examination of the gross structure of 10% aqueous dispersions was carried out using light microscopy techniques. Several functionality tests were performed, including determinations of water holding and water hydration capacities, protein solubility, steady shear flow behavior and viscoelasticity. Scanning electron microscopy was used to examine the microstructure of the gel-like materials produced when 10% aqueous dispersions of the products were heated in a boiling water bath. Both trypsin and linoleate treatment were observed to significantly affect the structural and functional properties of the products, although the treatment effects differed among sources in some cases. In general, trypsin-treated products contained smaller particles in dispersion, formed weaker gels on heating and exhibited higher solubility and water hydration capacities, and lower apparent viscosities in 10% dispersion. A trend toward larger particles in linoleate-treated product dispersions was observed along with stronger gel-forming abilities, increased solubilities, water hydration capacities and apparent viscosities in 10% dispersion. Simple correlation coefficients between several measured functional and compositional variables were computed to identify relationships among the physico-chemical properties. Both the size of the dispersed phase particles and the degree of interaction of the protein and carbohydrate components with water were determined to be important in governing functional properties.

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