Food grade antioxidants slow the oxidation, extend the shelflife and stabilize the refined oils and fats in baked goods, cereal-based snack foods, sauces, dehydrated soups and broths, processed nuts, seasonings and even dietary supplements.
Due to their unique purity, Eastman Chemical Company's (Kingsport, Tenn.) antioxidants are effective at very low concentrations and, when used at the proper level, do not affect food taste or smell.
Natural antioxidants such as tocopherols, ascorbic acid or spice extracts (such as those derived from rosemary) can be effective at providing oxidative stability but some “are not as effective in vegetable oils as they are in animal fats and butterfat,” says Tom Carter, a technologist in the food and cosmetics formulation lab of Eastman Chemical.
Synthetic antioxidants are derived from petroleum-based products. In the U.S., the following synthetic antioxidants have been evaluated by the FDA and are the most widely used: TBHQ (tertiary-butylhydroquinone), BHA (butylated hydroxyanisole), BHT (butylated hydroxytoluene) and propyl gallate. “These antioxidants are inexpensive and can be easier to process than natural antioxidants,” explains Carter.
BHA and BHT work well in combination, dissolve readily in most fats and oils, and are best suited to animal fats. Propyl gallate, while not so readily soluble, is more effective in vegetable oils. TBHQ is the most effective antioxidant for retarding oxidation in unsaturated fats like vegetable oils, making it ideal for snacks fried in vegetable oils.
Oxidative stability under the high heat of baking and frying can be achieved with lower levels of TBHQ than that of other synthetic antioxidants. BHA brings added stability to biscuits and cakes, also.
Antioxidants can benefit animal fats, including beef, poultry and pork by improving fat stability during shipping, storing and providing protection for increased shelflife.
Additionally, antioxidants can help to protect the nutritive value of foods in health and energy bars and vitamin-enriched cereals, which may spend weeks or even months on store shelves before being purchased.
Incompatibility between food additives and foods can lead to discoloration. For example, BHA and BHT are highly compatible, but propyl gallate can discolor when it comes into contact with iron. Testing the effectiveness of antioxidants will identify undesirable changes like color and taste. “If it's a bread product, make sure the leavening ingredients still function properly after antioxidants have been added,” says Carter. “If it's made with a lot of salt or higher pH, make sure the antioxidant is compatible with other food ingredients.”
Antioxidants come in two different forms, solids and concentrated solutions. Some antioxidants are added directly into fats and oils; others are sprayed directly onto food. “Regardless, it is important to add them early in the production process,” says Carter. “Because antioxidants cannot undo what time has already done.”