Phosphorus-to-phospholipid conversion factors for crude and degummed sunflower oils

Phospholipid composition and phosphorus content of several crude and degummed sunflower oils were measured in order to compare theoretical and experimental factors used to convert phosphorus content to phospholipid content. Differences in phospholipid content between sunflower oils obtained by different extraction and degumming methods were also considered. From FA and phospholipid compositions, average theoretical conversion factors of 24.7 and 23.0 were found for crude and degummed sunflower oils, respectively. The experimental conversion factor for degummed oils was in good agreement with the theoretical value. In contrast, fitted experimental factors were significantly lower for crude oils. The differences could be attributed to phosphorus from sources other than phospholipids and to the presence of minor phospholipids not quantified by chromatographic analysis. The relative phospholipid concentrations of oils depended on the method of extraction and the type of degumming. Solvent-extracted oils had a higher total phospholipid content, being generally more concentrated in PC and PE. The content of nonhydratable phospholipids was relatively low; acid or enzymatic degumming removed 40 to 70% of these phospholipids.