Oil droplets from the centrifuge sludge of a palm oil mill were separated by high speed centrifugation, dried and extracted with organic solvents, methanol and chloroform. The oil droplets (73 wt %) was solvent extractable. The extract was determined to consist of 84 wt % neutral lipids and 14 wt % of complex lipids (6 wt% glycolipids and 10 wt% phospholipids). The neutral lipids consisted of 83% triglycerides, 8% diglycerides, 0.5% monoglycerides and 8.0% free fatty acids.

Five types of glycolipids were determined and identified as digalactosyl diglycerides (22%), steryl glycosides (17%), cerebroside (9%), monogalactosyl diglycerides (20%) and esterified steryl glycoside (26%). Five types of phospholipids were determined and identified. They were phosphatidylethanolamine (21%), phosphatidylglycerol (37%), phosphatidylcholine (17%) and phosphatidylserine together with phosphatidylinositol at 11%. Palmitic acid (C16:0) and oleic acid (C18:1) were the major fatty acids found in the lipids.

The oil droplets found in the sludge were not unruptured oil droplets inherent in ripe mesocarp or young palm fruits. From the chemical analysis of the lipids associated with the oil droplets, it was deduced that oil droplets from the sludge are indeed formed in the milling process and possibly stabilized by the surface active agents of mainly phospholipids and glycolipids. The relatively high concentration of such biosurfactant in the oil droplets may have commercial potential as a value-added resource from the palm oil milling process.