Abstract: A natural antioxidant for pet food and/or pet food ingredients to extend the shelf life of the pet food and/or pet food ingredients. The natural antioxidant is a natural smoke antioxidant obtained from fractions of natural liquid smoke. A pet food or pet food ingredient that contains a phenolic fraction of a liquid natural smoke flavor (or “the natural smoke extract”). The phenolic fraction exhibits an antioxidant effect on the pet food or the pet food ingredient, such as delayed oxidation or hydrolysis of fats and oils, whereas fats include animal fat and oils include vegetable oils; or stated differently, the delayed rancidification of the pet food or pet food ingredient.