Physicochemical and Rheological Properties and Microstructure of Canola oil as Affected by Monoacylglycerols

Background and Objectives: Canola oil is very low in saturated fatty acid (8 %), which makes it suitable for application as dressing for salad. Canola oil is liquid, thus its application in the production of margarine and shortening is limited. The present study provides information about the effects of monoacylglycerols (MAG) as the structuring agent on physical, microstructure and rheological properties of canola oil. Materials and Methods: Canola oil was added 0.5, 3.0 and 5.0% MAGs. Fatty acid composition, iodine value (IV), slip melting point (SMP), solid fat content (SFC), rheological properties (viscose, elastic and complex moduli, complex viscosity and tan) and its microstructure by polarized light microscopy (PLM) were evaluated. Results: MAGs at 0.5% concentration, did not affect the saturated fatty acid (SFA) content; however, at 3 or 5% concentrations, SFA content increased (P< 0.05). MAGs increased solid fat content (SFC) of fats proportional to MAG content. At 0.5% concentration, MAGs had no effect on SMP, but at higher concentrations, SMP increased with MAGs concentration. With the increase of MAGs concentration, the induction period of crystallization decreased and crystallization rate increased at all temperatures. In spite of the decrease of tan by MAGs addition, samples containing higher MAG concentration had higher viscose, elastic and complex moduli and complex viscosity. PLM images indicated that MAG addition resulted in an increased hardness of canola oil. Conclusions: Canola oil structured with MAGs, can find its application in the production of liquid margarines and shortenings suitable for the use in bakery.