DETERMINATION OF NEUTRAL LIPIDS IN REGULAR AND LOW-FAT EGGS BY HIGH-PERFORMANCE TLC WITH DENSITOMETRY

A simple quantitative HPTLC method was developed for determination of cholesterol esters, triacylglycerols, free fatty acids, and cholestero l in hens' egg yolk. Lipids were extracted with chloroform-methanol (2 :1), the extract was passed through a glass wool column, and the eluat e was chromatographed on laned preadsorbent silica gel HPTLC plates wi th bracketing standards using the Mangold developing solvent for the l atter three lipid classes or a modified Mangold solvent for cholestero l esters. Lipids were detected with phosphomolybdic acid spray reagent , and zones were quantified by densitometric scanning. The method was used for the analysis of four regular and four lowfat eggs, and it was found that there was no significant difference between the two types of eggs except for a lower concentration of free fatty acids in the lo wfat eggs. There was no significant difference between the mean choles terol content of either type of eggs in this study and 18 regular eggs analyzed in 1987. Fractions containing monoacylglycerols, diacylglyce rols, and nonpolar hydrocarbons were identified in yolk from both type s of eggs, but amounts were not quantified.