Free and esterified sterol composition of edible oils and fats

The free and esterified sterol concentrations in 31 edible oils and fats were determined, including individual values for sitosterol, campesterol, stigmasterol, brassicasterol, Delta(5)-avenasterol, sitostanol, campestanol, and cholesterol. Free and esterified sterols were separated by solid-phase extraction (SPE), saponified, and quantified as trimethylsilyl ether derivatives using capillary gas-liquid chromatography. Considerable variability in the proportion of free and esterified sterols was observed among different oils and fats, with free sterols ranging from 32 to 94% of total sterols. Refining or hydrogenation tended to decrease total sterols and increase esterified sterols. Differences in total phytosterol content and the proportion of free and esterified sterols also were evident for different samples of some oils. Among four soybean oils, total phytosterols ranged from 205 to 287 mg/100 g, and free sterols constituted 68-81% of total sterols; two different shortenings differed 62% in total sterol content (185-301 mg/100 g). Such variability in phytosterol composition likely reflects differences in processing, growing season, or variety of a particular plant source. (C) 2002 Elsevier Science Ltd. All rights reserved.