Determination of neutral lipids from subcutaneous fat of cured ham by capillary gas chromatography and liquid chromatography

The determination of neutral lipids in fat of cured ham is reported. Fat samples were extracted with chloroform-methanol (2:1) and neutral lipids and free fatty acids were separated on an aminopropyl minicolumn, the first fraction with chloroform-2-propanol (neutral lipids) and the second fraction with 2% acetic acid in diethyl ether (free fatty acids). Neutral lipids were fractionated with minicolumns, with aminopropyl and silica stationary phases. Two fractions were obtained with the first column: (A) triglyceride and cholesteryl esters and (B) cholesterol and mono- and diglycerides. Fraction A was applied to the silica column to obtain two new fractions: (C) cholesteryl esters and (D) triglycerides. Fractions B and C were analysed by capillary gas chromatography (cGC) and fraction D by cGC and HPLC. The R.S.D.s obtained were below 5% except for the monoglycerides (8%). Cholesteryl esters were determined by cGC in 5 min with R.S.D. 5%. The main triglycerides identified were PPO, POS, POO, POL and OOO (P = palmitic acid, O = oleic acid, L = linoleic acid; S = stearic). Monoglyceride and diglycerides having 18, 34 and 36 carbon atoms were the most abundant. The determination of triglycerides by HPLC was more difficult than by cGC because the linearity with HPLC was concentration dependent. The procedure allowed the determination of neutral lipid classes without derivatization of mono- and diglycerides.