Fat oxidation
Lipid degradation by auto-oxidation has long been an issue in baked goods because many recipes rely on butter or vegetable oils for flavor and performance. Fats oxidize when fatty acids react with air, moisture or other compounds and break down into free fatty acids and other unstable compounds.
In general, the more polyunsaturated fatty acids on a fat molecule, the faster it breaks down. This happens because the unstable double bonds participate in the chain reaction of degradation processes. When fats oxidize, they develop objectionable flavors and odors described as rancid.
Oxidative rancidity significantly impairs the shelf life of baked goods, according to Peter VanAlstyne, a Kalsec scientist who studies natural antioxidants in food systems. Major factors affecting oxidation in baked goods include fat content, fat composition, oxygen, water and protein content, surface area exposed to oxygen and light, and presence of transition metal ions.
“Among these, fat content and fat composition play the greatest roles in oxidation,” Mr. VanAlstyne said. “The amount of fat contained within any particular baked good will have a direct influence on how quickly the product will oxidize.”
Whole grains have grown in popularity because of their health benefits, but they are much more susceptible to turning rancid because of the oil content in the wheat germ,
Ms. Leahy noted. “Nuts are affected in much the same way, and when added to formulas, they run the risk of cutting the shelf life of the end product,” she said.
Environment may impact fat stability, too. “Don’t forget that light will cause photo-oxidation,” said Chandra Ankolekar, technical service manager at Kemin. “Baked goods in clear packaging will have a shorter shelf life. Antioxidants can assist.”
However, antioxidants cannot prevent oxidation. They only delay the breakdown of lipids by quenching free radicals, which, if left unchecked, accelerate the process, according to Jim Anderson, North America sales manager, Camlin Fine Sciences. “Once oxidation is initiated, by-products are formed that cause the food to taste or smell different,” he said. “Color changes in the food product might also be a side effect of oxidation.”
Traditional synthetic antioxidants are very effective, easy to use and low cost. But being chemically derived, which is obvious by their names — butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), ethylenediaminetetraacetate (EDTA) and tertiary butylhydroquinone (TBHQ) — they are undesirable in today’s clean-label baking environment. In response, bakers are embracing naturally sourced antioxidants that can be discreetly added to product formulations. Common options are classified as tocopherols and high-phenolic plant extracts, such as those from rosemary, green tea, acerola and licorice.
“Synthetic antioxidants are very effective, have little impact on the sensory attributes of food products and are also cost-effective,” Ms. Schwartz said. “However, recent consumer demand for cleaner, easier-to-read labels has made them the less popular choice.”
Clean-label ingredients with antioxidant properties are available. Many can be just as effective but often require reformulation work to keep them from negatively impacting sensory attributes. They may be more costly as well.
“Rosemary extract ingredients provide great protection against color and off-flavor development in baked goods,” Ms. Schwartz said. “Oil-soluble green tea has been proven to provide equally effective protection to that of TBHQ in a number of fats and oils used in baked goods. It is a great label-friendly alternative.”
Kalsec provides natural antioxidant solutions for bakers. “Our flagship brand consists of rosemary extracts standardized for antioxidant activity and flavor impact,” Mr. VanAlstyne said. “These products come in both oil-soluble and water-dispersible options for ease of use in the manufacturing process. We also offer combinations of two or more antioxidants, including rosemary, tocopherols, ascorbic acid and green tea, to provide maximum natural protection.”
Read on to see how different companies are putting these shelf life principles to work.
