Marinades often consist of an acidic component that help to flavor and tenderize meat by weakening its muscle structure. Common acids are fresh citrus juices, wine or alcohol, vinegars and cultured milk products such as buttermilk, yogurt, and sour cream.

The acids in certain tropical fruits, such as papayas, kiwis, pineapples or figs, contain particular enzymes (papain in papaya and bromelain in pineapple) that will make the meat mealy or mushy if over-marinated. Butcher’s used to sprinkle a powdered form of papain over tough cuts of meat to make them tenderer.