Malic Acid is an organic compound that adds tartness to food products and can also be used as a preservative. Malic acid is found in a wide variety of fruits and vegetables including apples, cherries, tomatoes, and grapes and it can be found in wine. It may also be added to dairy products, processed fruit, condensed milk, soups, beer, malt beverages, and processed meat. Be warned — if you eat too much, it could irritate your mouth.