Trans fats naturally exist in small amounts in the fat in meat and milk, but most trans fats in the food supply have been added by food manufacturers. Since 1911, when Procter and Gamble introduced Crisco, companies have used artificial trans fats because of their commercially favorable properties, such as long shelf life, stability during deep frying, and palatability. These fats have therefore been incorporated into a great many foods, including snack and deep-fried foods, baked goods, margarines, and crackers.