Entrained Oil Loss Reduction and Gum Yield Enhancement by Megasonic-Assisted Degumming

The degumming step in seed oil refining is essential to avoid deleterious oxidative reactions caused by the presence of gums, which may impact on the refined oil stability and shelf life. However, conventional degumming techniques produce gums with significant amounts of entrained oil that is not recovered. The present work evaluated the application of megasonic waves during acid degumming of canola, soybean, and sunflower oils to recover entrained oil in the gums and increase the gum yield. Oil-acid mixing options were explored at selected temperatures and times, with and without a megasonic treatment (2 MHz, 340 W, 81.6 kJ/kg, 20 min). Megasonics best enhanced the acid degumming of canola oil after a one-pass ultra-turrax shearing for 3 min at 40 °C. Such megasonic-assisted acid degumming conditions were effective in reducing residual phosphorus content in both canola and soybean oil by 54.3% and 67.0%, respectively, but less effective in sunflower oil (39%, relative to the non-megasonic degumming). The megasonic treatment also reduced the loss of gum-entrained canola, soybean, and sunflower oil by 50.0%, 35.0%, and 28.4%, respectively. Furthermore, the gum yield (% w/w oil, dry basis) obtained from canola, soybean, and sunflower oil degumming was also enhanced by 22.7%, 18.7%, and 16.0%, respectively, compared with the control. The three megasonic-assisted degummed oils met industry standard specifications for refined seed oil, including free fatty acids, chlorophyll, peroxide, and phosphorus content. Income from additional oil and gum recovery, resulting from megasonics, was initially indicative of the economic viability of the process. Further cost benefit analysis is required, from pilot to industrial scale process data, to validate economic viability.