Vegetable oils from renewable resources such as rapeseed and soya are increasingly being processed into biodiesel. Fat-soluble components of the plant cell membrane, acetylated sterylglycosides, are also added to the oil in the oil mill. As valuable as these plant substances are for human nutrition, they are undesirable in biodiesel. During its production, during the transesterification of the tryglyceride of the oil to methyl esters, the accompanying substances lose their acetyl side chain. Unlike the acetylated form, the resulting steryl glycosides are not readily soluble in biodiesel and crystallize out during storage. Since the crystals are very small, even small quantities can clog the filters in the vehicle. Biodiesel manufacturers are therefore looking for a solution to selectively remove the unwanted plant substances from the oil.