Applicazione della fase cianopropilsilossano per la valutazione in GLC degli acidi grassi di Sardina pilchardus

The aim of the present study was the most complete identification of the acidic composition of the Sardina pilchardus fat. A TLC AgNO 3 technique was used together with GLC on a cyanopropylsiloxane phase (Supelco SP-2340). This latter is commonly used for the GLC separatlon of the configurational isomers of fatty acids. Identification of the methyl ester peaks was attained through various analytical approaches: a) comparison of the peak retention times with those of other lipids of known composition, of both vegetable and animal origin; b) comparison of the chromatograms with those produced from other GLC columns; GLC analysis of the bands previously separated through TLC AgNO3. Eighty peaks present in the methyl esters chromatogram of the Sardina pilchardus lipids were taken into consideration. They corresponded to 85 identified fatty acids, including some trans-isomers of the monoinsatured fatty acids. Among these, the C16:1 ω10 trans fatty acid is present at a level of 0.3% and the C18:1 ω9 trans and C18:1 ω7 trans are also present, but at lower concentrations. Although minor, the presence of C18:1 trans-isomers in the fatty acid composition of Sardina pilchardus must be carefully considered when judging the authenticity of olive oils used as the covering oil in canned fishes.