A fat molecule consists of three fatty acids and glycerol backbone. Fatty acids can be grouped according to the length of the carbon chain, the number of atoms, the number of double bonds and their position in the carbon chain. According with the number of double bonds in the carbon chain, FA are classified as saturated if no double bonds are in the carbon chain, the monounsaturated have only one double bond and polyunsaturated have two or more double bonds in the carbon chain.
An important classification of the unsaturated fatty acids is the cis-trans isomerism, the spatial arrangement of C – C bonds adjacent to double bonds. “Cis” means that the hydrogen atoms attached to the double bonded carbon atoms are on the same side of the fatty acid chain.
“Trans” means that the hydrogen atoms attached to the double bonded carbon are now on the opposite side of the fatty acid chain. The trans configuration is formed during the hydrogenation of unsaturated fatty acids. During the process, the twisted cis isomers are transformed into stable and straight-chain trans isomers, which are easier to combine with each other.
Visual taken from https://chemistrytalk.org/cis-trans-isomers/
Trans fats occur naturally in products or may be produced industrially. Trans fats are less expensive to produce, last a long time and are easy to use, giving foods a desirable taste and texture (American Heart Association, 2022). Many restaurants and fast-food outlets use trans fats to deep-fry foods because oils with trans fats can be used many times in commercial fryers.