TRANSESTERIFICATION AND ONLINE LC-GC FOR DETERMINING THE SUM OF FREE AND ESTERIFIED STEROLS IN EDIBLE OILS AND FATS

A method is proposed to substitute the classical saponification proced ure for the determination of the sterols and other minor components in edible oils and fats. Saponification is replaced by transesterificati on, which liberates sterols and alcohols from esters under mild condit ions, but does not form soap hindering the extraction of the neutrals. Triglycerides are turned into fatty acid methyl esters, which are rem oved by automated LC-GC. LC also pre-separates the minor components in to classes, e.g., of linear alcohols, triterpenes, methyl sterols, DEL TA5 sterols, and DELTA7 sterols. Multiple LC-GC transfer allows obtain ing several gas chromatograms from the same injection into LC. Sample preparation takes some 5 min; 10-25 samples can be analyzed by an LC-G C instrument, depending on the number of LC fractions transferred to G C per sample.