Improvement of the Canola Oil Degumming Process by Applying a Megasonic Treatment

Abstract

Crude canola oil from expeller pressing contains undesirable gums mainly composed of phospholipids, which must be removed to increase the oil’s shelf life. Degumming is carried out by high shear mixing of the oil with chemical reagents. This often requires multiple energy-consuming steps and is dependent on the phospholipid content of the oil being degummed. A set of process parameters at laboratory scale were selected to reproduce common industrial degumming processes (water, acid, and total degumming) and to compare with megasonic intervention before centrifugation. A factorial experimental design was applied to examine the effect of frequency (0, 0.4, 1, and 2 MHz; 33.6-122.4 kJ/kg), sonication treatment time (10, 20, and 30 min), and temperature (40, 60, and 80 °C) when applying megasonics during phosphoric acid degumming. Process parameters of 2 MHz at 40 °C for 30 min were the most efficient to reduce the residual phosphorus content from 27 mg/kg, on the non-megasonic water degummed oil, to 11 mg/kg, on the megasonic water degummed oil. Furthermore, the phosphoric acid and total degumming processes showed significant phosphorus reduction in the degummed oil when applying similar megasonic conditions (2 MHz at 40 °C for 20 min). The residual phosphorus with acid megasonic-assisted degumming was below the values achieved with a total degumming process without megasonics. This demonstrated that a megasonic intervention may eliminate the industrial alkalisation (neutralisation) while reducing the degumming processing time. A fatty acid composition analysis showed a noticeable reduction in the FAA and polar lipids with megasonic treatment after a total degumming process. However, there were no significant changes on both triacylglycerols (TAG), and diacylglycerols.