Investigation of Some Preparation Procedures of Fatty Acid Methyl Esters for Capillary Gas-Liquid Chromatographic Analysis of Conjugated Linoleic Acid in Meat

Abstract

The five most widely accepted procedures for preparing fatty acid methyl esters in food lipids were investigated for their suitability in capillary gas-liquid chromatographic analysis of cis-9, trans-11 conjugated linoleic acid (c-9, t-11 CLA) in meat. A modified procedure of fatty acid methyl esterification was developed and the method was applied to determine c-9, t-11 CLA content in some meats. This method involved hydrolysis of lipids with 0.5M KOH in methanol at 100°C for 5min, followed by esterification with aqueous HCI (35%)/ methanol (1:1 v/v) at 100°C for 5min. The resulting c-9, t-11 CLA methyl ester was separated by gas-liquid chromatograph equipped with a capillary column and determined using tricosanoic acid as an internal standard. Meat from ruminant animals considerably contained more c-9, t-11 CLA than those from non-ruminant animals in the following order: goat meat, beef, mutton, pork, and chicken. The amount in goat meat (6.35mg/g lipid) was 10-fold greater than those in pork and chicken.