Catalase, an enzyme that catalyzes the breakdown of hydrogen peroxide into oxygen and water, is present in the peroxides of cells. Catalase is a marker enzyme of peroxidase, accounting for about 40% of the total peroxidase. Catalases are present in all tissues of all known animals, especially in the liver with high concentrations. Catalase is used in the food industry to remove hydrogen peroxide from milk used to make cheese. Catalase is also used in food packaging to prevent food from being oxidized.