What foods contain trans fatty acids?

Trans fatty acids, also known as hydrogenated fatty acids, are unsaturated fatty acids. Scientists use hydrogenation process to turn liquid vegetable oil into solid, thus producing trans fatty acids. In 1980s, trans fatty acids were used as substitutes for saturated fatty acids. At that time, scientists were worried that saturated fatty acids in meat oil might pose a threat to the heart, and vegetable oil was unstable at high temperature and could not be stored for a long time, so hydrogenation process was used to turn liquid vegetable oil into solid state. Since then, trans fatty acids have been widely used. It is understood that trans fatty acids produced by hydrogenation of unsaturated fatty acids account for 8%~70%, while naturally occurring trans fatty acids in milk, dairy products and beef and mutton fats account for 2%~9%. By German chemist William? Invented by Norman and patented by 1902. Its manufacturing principle is to heat vegetable oil, add metal catalyst and introduce hydrogen to make liquid oil become semi-solid oil. Hydrogenated oil is welcomed by people for its solid state, better storage than liquid natural vegetable oil, lower price than natural animal fat, long shelf life and good taste. However, in the process of hydrogenation, some fats become trans fats. Trans fat is not good for human health, nor is it a nutrient needed by human body. Margarine is harmful to human body because of trans fats. If a food label uses margarine (cream), trans fat, artificial vegetable butter (cream), artificial fat, hydrogenated oil, hydrogenated palm oil, shortening, vegetable shortening, etc. Then this kind of food generally contains trans fatty acids.