Phospholipid‐ phospholipid interaction in soybean oil

Abstract Phospholipid‐phospholipid interaction in soybean oil is described. Phosphatidylcholine was effectively removed from soybean oil by degumming (water hydration), whereas phosphatidylethanolamine and phosphatidic acid were hardly hydratable. However, the degree of their hydration increased in the presence of phosphatidylcholine. The spectrophotometric assay based on charge transfer interaction between 7,7,8,8‐tetracyanoquinodimethane and phospholipids at 480 nm was used to determine the formation of phospholipid micelles in soybean oil. The critical micelle concentrations were 0.085, 0.84 and 2.6 mM for phosphatidylcholine, phosphatidylethanolamine and phosphatidic acid, respectively. Phosphatidylcholine interacted with phosphatidylethanolamine or phosphatidic acid to form mixed micelles. The critical micelle concentrations of phosphatidylcholine‐phosphatidylethanolamine mixture and phosphatidylcholine‐phosphatidic acid mixture were 0.16 and 1.3 mM, respectively. The degree of hydration of phospholipids was related to their critical micelle concentrations. Interaction of phosphatidylcholine with phosphatidylethanolamine or phosphatidic acid was confirmed by determining the changes in the chemical shifts of 31PNMR spectra.