How antioxidants delay oxidation and rancidity

by Laurie Gorton
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There are good reasons to use antioxidants in bakery fats to scavenge free radicals and/or chelate metals. Cathy Dorko, industry manager, fats and oils, for DuPont Nutrition & Health, New Century, KS, explains the mechanisms involved and how formulators can properly specify use of these additives, offered in both natural and synthesized forms. 

Baking & Snack: What is the mechanism by which antioxidants restrict oxidation? What does this mean to the shelf life of ingredients and finished baked goods and snacks?

Cathy Dorko: Antioxidants will delay or inhibit oxidation by either scavenging free radicals or chelating metals that can act as catalysts of oxidation. Antioxidants will delay the onset of oxidation and rancidity, slow deterioration of flavor and color and minimize nutritional loss and extend shelf life of the fat or oil. The extent of inhibition/delay will depend on the number and position of double bonds in the lipid (amount of unsaturation), processing conditions, exposure to high temperatures, oxygen and metals, and type of antioxidant used.

What should a formulator know about these materials and their usage levels? Are there limits to their use? How must they be labeled in the ingredient listing on packages?

Antioxidants should be selected based on: the fat or oil that is being used in the application; processing conditions (BHA, BHT and propyl gallate are not suitable for frying); regulations (Does the product have a standard of identity? Which antioxidants are approved for the product? Any restrictions?); shelf life required; packaging material; etc. DuPont's oxidation experts can help selecting the most effective antioxidant for a customer's application.

Natural extracts, mixed tocopherols and ascorbyl palmitate can usually be added based on Good Manufacturing Practices (GMPs) unless a food has a Standard of Identity. There are generally no maximum allowable levels for these ingredients; however, cost and flavor may limit the amount that is practical. BHA, BHT, TBHQ and propyl gallate have established maximum allowable levels, generally 200 ppm singly or in combination based on weight of fat or oil in a product. Natural extracts can be labeled in the US as a natural flavor or extract. Mixed tocopherols, ascorbyl palmitate, BHA, BHT, TBHQ and propyl gallate will be labeled by their common and usual names with a parenthetical description of their function (to protect flavor, color, etc.). Mixed tocopherols can be indicated as a natural antioxidant in the parenthesis.

What antioxidant ingredients does DuPont Nutrition & Health offer for bakery and snack applications?

DuPont Nutrition & Health offers a full portfolio of antioxidants and natural extracts with antioxidant properties that delay oxidation and rancidity including: The GUARDIAN natural extract product line includes TOCO 70 mixed tocopherols, rosemary extract and green tea extract. DuPont's GRINDOX Antioxidant range includes all food-grade antioxidants based on ascorbyl palmitate, BHA, BHT, TBHQ and propyl gallate as well as combinations of these antioxidants, chelators and carriers.

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