Direct ceramic membrane degumming of undiluted crude soybean oil: Quality changes and aqueous membrane regeneration

The traditional chemical degumming of crude oil generally results in chemical waste generation, high energy consumption, and reduced oil quality. Ceramic membrane filtration has been increasingly applied in food processing. This study directly employed ceramic membranes to filter undiluted crude soybean oil, comparing the effects of operating conditions on degumming efficiency and oil quality. At a transmembrane pressure of 0.4 MPa and a feed temperature of 60 °C, the 15 nm ceramic membrane achieved a phospholipid removal rate of 97.8%, and the acid value decreased from 1.485 mg/g to 0.992 mg/g. In contrast, the maximum reduction in peroxide value was 28.3%, which was obtained with the 20 nm ceramic membrane. However, smaller pore sizes increased peroxide value, likely due to prolonged oxygen exposure. Fatty acid profiles remained largely stable, with unsaturated fatty acids above 83.6%. TGA and FTIR identified membrane foulants as organic compounds, mainly triglycerides and aromatics. A three-step cleaning strategy was adopted, 30 g/kg NaOH → 15 g/kg HNO 3 → 5 g/kg sodium dodecylbenzenesulfonate. The cleaning strategy proved effective, and the flux recovery rate is more than 97 %. After 3 cycles of pollution and cleaning, the recovery rate remained above 95.8 %, indicating that the process had long-term operational stability. These findings indicate that ceramic membrane filtration can directly degum undiluted crude soybean oil and enabling effective aqueous membrane regeneration.