Evaluation of the role of saturated fatty acids in sedimenting canola oils

Canola oil is generally a clear oil which does not require winterization. However, sediment formation has become an increasing problem in Australian canola oil. Canola oil stored at temperatures between -5 and 21 °C formed sediment more rapidly at lower temperatures. The sediment and clear fractions of a group of sedimenting canola oils were analyzed and compared. Both fractions contained wax esters of carbon number C42-C52, the sediment fractions containing between 0.37 and 3.09 mg g^-1 and clear fractions containing between 0.12 and 0.85 mg g^-1. The triacylglycerol profiles of sediment fractions contained four compounds, PPO, PPP, PSO and PPS (where P is palmitoyl, O is oleoyl, and S stearoyl), that were not detected in clear fractions. The contents of palmitic acid and total saturated fatty acids were higher in the sediment fraction than the clear fraction. Added PPP clouded a clear oil as effectively as stearyl behenate and more than OOO or lauryl arachidate. Sedimentation may be linked to environmental conditions, as seed grown in 1997, a dry year, produced more problem oils than seed grown in previous years that had more nearly average rainfall.