49 Virgin Olive Oil Benefits 2.2. Dietetic sources and trans fatty acid consumption There are two main sources of dietary trans fatty acids: - Most (>90%) come from the intake of industrial partially hydrogenated fat obtained at high temperatures and pressure, as well as with metal catalysts. These products can be used to make biscuits, snacks, margarine, pastries, pizzas and the like. Currently, high melting-point fats can be produced by enzymatic interesterification without trans fatty acid generation. Such fats are employed in countries, including those belonging to the European Union (EU), where legislation does not allow to use trans fatty acids. Indeed, for some time now in the EU, margarine, industrial confectionary, and snacks have not presented appreciable amounts of trans fatty acids. However, in Latin America and Asia, the content of trans fatty acids in fats is high yet. Partially hydrogenated oils usually contain a large amount of trans fatty acids, whilst totally hydrogenated oils do not because all the double bonds have been brought to saturation. However, these saturated fats are not advisable for health reasons particularly cardiovascular ones (Figure 2.2). If partia ly hydrogenated fat appears on a food label, high quantities of trans isomers could be present in such food. - Other dietetic sources of trans fatty acids (around 2-8% of the total ingested fatty acids) come from dairy products and ruminant meats. They occur as a result of biohydrogenation produced by ruminant bacteria. Figure 2.2. Fat hydrogenation Classical industrial process for fat hydrogenation. 18:2: Linolenic acid; 18:1: Oleic acid; 18:0: Stearic acid; H: Hydrogen; C: Carbon; 18:2 18:1 18:0 C C H Figura 2 18:2 18:1 18:0 • Isómeros de posición sómeros geométricos:AGtrans • Saturación de los dobles enlaces • Ácidos grasos saturados • Isomerización de dobles enlaces C C H Figura 2 • Double bonds saturation • Double bonds isomerization • Saturated fatty acids • Geometric isomers: trans fatty acids • Position isomers Hydrogen, catalyst, temperature
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