Trans Fat is a type of fat that is created when oils are partially hydrogenated, which occurs by adding hydrogen to the oil so it becomes solid rather than liquid. The process of hydrogenation will change a liquid oil into a saturated fat making it a stiffer and more stable form, such as changing a vegetable oil into a stick of margarine, producing trans fatty acids as a result.
Similarly, foods such as potato chips are more shelf-stable and are crispier with the addition of the trans fat. Any foods containing hydrogenated oil, even partially hydrogenated oil, will contain trans fatty acids. Typical foods containing trans fatty acids are margarine, baked goods, fried foods, and processed foods such as crackers and snacks.
Trans Fats are the chemically modified food ingredients that raise levels of a particularly unhealthy form of cholesterol and have been squarely linked to heart disease. Long used as a substitute for saturated fats in baked goods, fried foods, salad dressings, margarine and other foods, Trans Fats also have a longer shelf life than other alternatives.