Plant sterols in vegetable fats and oils processed in the United States

Campesterol, stigmasterol, and β-sitosterol were quantitated by gas chromatography in corn, coconut, cottonseed, soybean, and palm oils at various steps of processing: in corn oil margarine and in shortening. The latter two also were processed in the United States. Without prior clean-up, the unsaponifiable components were used to form sterol acetates and were chromatographed on a 3% OV-101 (80-100 mesh chromosorb W-HP), 1.83 m X 4.23 mm i.d. glass column at 272.5°C utilizing cholestane as an internal standard. The accuracy and the precision of the method were determined. All the stigmasterol added to hydrogenated palm oil was recovered at lower concentration level (0.5 mg added), and 81.9% of the campesterol, and 92.5% of β-sitosterol added were recovered. Precision of the method determined as the coefficient of variation of each sterol content was ± 10%. Sterol content decreased progressively as oils were refined, deodorized, winterized, and hydrogenated. Campesterol, stigmasterol, and β-sitosterol content, mg/100g sample, respectively, in fats and oils as consumed were: 28-32, 29-33, and 104-127 for soybean oil; 12-23, 1-5, and 153-347 for cottonseed oil; 2-12, 2-16, and 8-34 for palm oil; 3-4, 6-7, and 39-58 for coconut oil; 58-138, 28-46, and 299-701 for corn oil; 27-90, 14-30, and 120-436 for margarine; and 11-24, 12-27, and 52-105 for shortening. No significant changes were observed in the compositional ratio of the sterols at any stage of processing. Tentatively identified brassicasterol, relative retention time (RRT, cholestane): 2.70, and Δ⁵-avenasterol, RRT (cholestane): 4.25, peaks were detected in small amounts in nearly all of the fat and oil samples. The presence of peculiar unknown sterol was found in coconut fat and deodorized fully hydrogenated cottonseed oil. Unknown components: RRT (cholestane): 1.44, 1.60, and 1.75, in several fats and oils were tentatively identified as tocopherols.