Browsing by Subject "napiini"

The literature review examined structures and functionalities of two major canola proteins, cruciferin and napin. In addition, fundamental functional properties of proteins and the impact of high intensity ultrasound on functionality of other proteins were reviewed. Ultrasound treatment has been successfully used to improve several functional properties of other proteins such as soy, pea and egg white proteins. However, research on high intensity ultrasound treatment for improving canola protein functionality is limited. The aim of the experimental part was to improve solubility, rheological and emulsification properties of canola proteins using high intensity (20 kHz) ultrasound. The effects of ultrasound treatment on protein structures were also examined. Canola samples were first preheated (95 °C, 5 min) and then treated with ultrasound at different power intensity levels (200 and 400 W) and durations (10 and 30 min). Albumin fractions were obtained by water extraction (pH 7.3) and NaCl extraction (1 M, pH 6.3) was used to obtain globulin fractions. The soluble protein concentration was determined using DC Protein Assay (Bio-Rad, USA), free sulfhydryl content was measured according to Ellman’s procedure and electrophoresis (SDS-PAGE) was performed for the determination of protein composition. Emulsifying ability, creaming index, average particle size, viscosity, storage modulus (G’) and loss modulus (G’’) were determined from the heat-induced emulsion gels. Solubility and emulsion stability of ultrasound treated canola samples were improved compared to control samples. In addition, ultrasound treatment reduced the average particle size. However, the electrophoretic profiles of the control and ultrasound treated canola protein samples did not differ significantly. Based on the rheological measurements, all the emulsion gels were shear thinning and indicated elastic properties (G’>G’’). These results suggest that high intensity ultrasound treatment modified the structures of canola proteins enabling increased molecular interaction and enhancing particularly emulsion gel stability.