In November of 2006, the New York City Department of Health issued a citywide ban on the use of trans fats in restaurants. Another directive has been to post calorie counts on menus as well, but we’re not dealing with this subject today. It’s the fats issue that has me preoccupied.
First, let’s get our facts straight. Trans fats cannot be seen, nor bought at the market. They are technically known as trans fatty acids, and are part of some other fat or oil that can in fact be bought.
Fats are made of chains containing mostly carbon and hydrogen (there may be as many as 24 carbons in a chain). Each carbon has four bonds, and each hydrogen has one, so a single carbon atom can hook up with four hydrogen atoms. In a saturated fat chain, each carbon atom hooks up with two hydrogens and one other carbon (except the first and the last ones); in other words, saturated fats have only single bonds between carbons.
A mono-unsaturated fat has one double bond between two carbons only, and therefore is missing two hydrogen atoms.
Polyunsaturated fats have two or more double bonds between three or more carbons, and they are missing even more hydrogen atoms, which makes them liquid at room temperature.
Hydrogenation or partial hydrogenation is an industrial process that forces hydrogen back onto the carbon chain, thereby artificially saturating it again. It is that process that causes the appearance of the trans fats.