Efectos producidos por la hidrogenacion sobre los aceites y grasas comestibles. Acidos grasos transinsaturados. Contenido en los alimentos.

The eating patterns in Spain has changed during recent decades, specially increasing use of procesed vegetable fats and oils, relative to animal fat intake. This change has resulted in an increased intake of chemically altered fatty acids (FAs) known as trans FAs. Trans FAs intake has been related to several biological effects. From a nutritional point of view the loss of the essential character of polyunsaturated FAs may be particulary important, also, increase the ratio of plasma low-density-lipoprotein to high-density-lipoprotein cholesterol, so it is posible that they adversely influence risk of coronary heart disease. A method for the determination of the fatty acidss composition, by gas chromatography (CG) on capillary column, has been established. The analyses was performed using a chromatograph Hewlett-Packard model 5880 with flame ionization detector (FID). We have studied the trans isomers contents of the FAs fraction in 400 samples of comercial spanish foods, after a previous fat extraction and gas chromatography determination usign CP Sil 88 coated capillary columns. The results obtained show a great variability in the total trans fatty acids (%) contents, from 0,1 ± 0,1 in refined olive oils to 16,8 ± 5,7 in margarines and 20,9 ± 12,9 in french fries potatoes of burger.