Quantitation of Sterols and Steryl Esters in Fortified Foods and Beverages by GC/FID

Direct extraction methods for the quantitation of sterols and steryl esters (SE) in foods, beverages and concentrates as free sterols (trimethylsilane ether derivatives) by gas chromatography with flame ionization detection (GC/FID) are introduced. Theoretical correction factors are used for sterol quantification relative to the internal standard, Epicoprostanol. Conversion of the acylglycerols, when present, into FFA eliminates the time-consuming acylglycerol extraction step and reduces the GC run time since no higher molecular weight acylglycerols need to elute from the column. Accuracy and precision of analytical data are important when formulating food products with sterols or SE to ensure a formulation will meet health claims, while at the same time minimizing costly over formulation. Method accuracy was determined by complete recovery of sterol and SE concentrates as free sterols with subsequent analysis of foods and beverages formulated with sterol and SE concentrates. Triplicate analysis over 5 days demonstrated repeatability for the alkaline saponification and acid extraction with alkaline saponification methods. A relative standard deviation of < 5% demonstrates the repeatability of the methods. Replicate analysis of a common sample by two laboratories and replicate analysis of a common sample by multiple analysts demonstrated reproducibility of the methods.