HPLC analysis of phospholipids in crude oil for evaluation of soybean deterioration

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Abstract
Damage to soybeans due to pre‐harvest stress, storage, and export shipment has been related to an increase in the nonhydratable phospholipid content of crude oil. Phospholipids in crude soybean oil extracted from such distressed soybeans have been analyzed by gradient high‐performance liquid chromatography. Crude oil was fractionated by solid phase extraction using sequential elution for recovery of phosphatides. High‐performance liquid chromatography of the concentrated phospholipids was accomplished on a Lichrosorb Si‐60 10 μ column, 250×4.6 mm with ultraviolet detection at 206 nm. A 20‐min solvent gradient of 2‐propanol/hexane/water (42∶56∶2, 51∶38∶11) gave retention profiles of phospholipid distribution (major subclasses) that changed with impact of stress applied to plant or seed. Soybeans stored at high moisture levels (16% and 20% moisture) for up to 28 days yielded oils having phosphorus contents which decreased in direct relationship to days of storage. Retention profiles were unusable for fractions isolated from oils with phosphorus content below 100 ppm. Data show that during progressive damage, the content of phosphatidylcholine and phosphatidylinositol decreased while the phosphatidic acid content increased.