ABSTRACT
This section focuses on quantitative functional analysis of essential omega-3 fatty acids, namely EPA, DHA, and ALA [Hurst 2002]. For the quantitative estimation of fatty acid pro le in complex matrix (functional foods), the usual steps are extraction to release the free fatty acids, derivation of the released fatty acids, and chromatogram analysis with GC with ame ionization detection, although other techniques such as GC-MS and HPLC have been used with success [Hurst 2002]. The Folch method of lipid extraction, using chloroform and methanol as solvents in the volume ratio of 2:1, is most common [Hurst 2002]. To eliminate the nonlipid contaminants such as carbohydrates and amino acids, the components chloroform-methanol-water/0.88% potassium chloride must be adjusted to 8:4:3 by volume, yielding a biphasic system
[Hurst 2002]. The free fatty acids are then usually derivatized to fatty acid methyl esters (FAMEs) [Hurst 2002]. These derivatives are volatile and render themselves to excellent gas chromatographic analysis [Hurst 2002]. In GC, the area percentage of each FAME peak is proportional to the weight percentage of each FAME [Hurst 2002]. However, this method overestimates long-chain fatty acids and underestimates short-chain ones. Neglecting this caveat, this is still the most commonly used procedure [Hurst 2002]. The quanti cation of individual FAME in milligrams per gram of the total sample is facilitated by the use of an internal standard, which can be added during either extraction or derivatization process [Hurst 2002]. Recently, GC-MS and HLPC techniques to characterize DHA and ALA have been reported [Hurst 2002].
