VALIDATION OF DIGLYCERIDE CONTENTS IN CHEESES USING COORDINATED CHROMATOGRAPHIC TECHNIQUES

This paper describes a method suitable for the analysis of diglyceride s (DG) in cheese. The method, also suitable for other foods, is essent ially based upon the solid-phase extraction (SPE) of DG followed by ca pillary gas chromatographic analysis with a polar stationary phase (TA P). SPE is applied to avoid the column overloading caused by triglycer ides; however, SPE is able to catalyse isomerization from the 1,2-form to the 1,3-form. This introduces an error into the results, as the tw o forms have different origins and are produced at different stages of ripening. A comparison between the use of silica and diol phases was made and it was seen that no isomerization occurred when the diol phas e was used. Repeatability and recovery trials were carried out and the coefficient of variation (relative standard error) of the former tria l was approximately 10%. Finally, it is demonstrated that it is possib le to re-use the SPE cartridge at least four times.