Study of isomeric trans-fatty acids content in the commercial Spanish foods.

A method for the determination of the fatty acids (FAs) composition, by gas chromatography (GC) on capillary column, is described. The analysis was performed using a chromatograph Hewlett-Packard model 5890 with flame ionization detector (FID). We have studied the trans isomers contents of the FAs fraction in 551 samples of commercial Spanish foods, after a previous fat extraction and gas chromatography determination using a CP Sil 88 coated capillary column. The results obtained show a great variability in the percentage of total trans fatty acids contents, ranging from 0.1% in refined olive oils to 20.9% in french fries.