A natural antioxidant found in grain bran could preserve food longer and replace synthetic antioxidants currently in use, according to new research.
“Currently, there’s a big push within the food industry to replace synthetic ingredients with natural alternatives, and this is being driven by consumers,” says Andrew S. Elder, doctoral candidate in food science at Penn State.
“Consumers want clean labels—they want synthetic chemical-sounding ingredients removed because of the fact that they don’t recognize them, and that some of them (the ingredients) have purported toxicity,” Elder says.
The researchers studied a class of compounds called alkylresorcinols (AR). Plants such as wheat, rye, and barley produce ARs naturally to prevent mold, bacteria, and other organisms from growing on the grain kernels. The researchers wondered if ARs could also preserve food in the same way from a chemical standpoint.
Along with using more natural ingredients, the food industry is also supplementing more foods with healthy oils rich in omega-3 fatty acids. Adding these healthy oils to foods that normally wouldn’t have them could boost their health benefits. However, omega-3 rich oils have a shorter shelf life, which could cause the foods to spoil more rapidly.
“We’re taking something that’s usually discarded in a waste stream and turning it into something useful.”
“Most people consume omega-3s from marine sources,” says Elder. “As they break down, they can make the product smell and taste fishy. Consumers then throw these products out and don’t buy them again, and this results in an economic loss.”
Antioxidants are compounds that slow the rate at which omega-3 fatty acids degrade, preserving their health benefits and preventing food from spoiling as quickly. While consumers demand more natural ingredients, the food industry has struggled to find natural antioxidants that are as effective as synthetic ones.
“There are not many natural alternatives for synthetic antioxidants,” says Elder. “Our work is focused on identifying new natural antioxidants to extend the shelf life of food and meet consumer demands.”
Trash to treasure
ARs have health benefits for humans as well and can help protect against cancer, according to a review that appears in European Food Research and Technology, making them ideal natural additives. ARs also come from the bran layer of cereal plants, which the food industry usually discards or uses for animal feed.
“Bran is often a waste stream,” says Elder. “We’re taking something that’s usually discarded in a waste stream and turning it into something useful.”
The team developed a technique to extract and purify ARs from rye bran, then studied how well ARs were able to preserve omega-3-rich oils in emulsions, where two fluids do not fully mix—for example, vinegar and oil. The researchers chose to study AR action in emulsions because most people consume oils as emulsions, such as salad dressings.
The researchers found that ARs did act as antioxidants in an emulsion, preventing omega-3 oils from spoiling as rapidly as they did in emulsions with no antioxidants added. Then, they compared ARs to two antioxidants widely used by the food industry—alpha-tocopherol or Vitamin E, a natural antioxidant; and butylated hydroxytoluene, a synthetic antioxidant. However, ARs were not as effective as either the natural or the synthetic antioxidant.
The various stages of processing rye, from berries to alkylresorcinols (top left to bottom right): rye berries, rye chops (coarsely ground rye berries), rye bran, and alkylresorcinols (extracted and purified from rye bran). (Credit: Ben Chrisfield/Penn State)
Although the ARs did not work as well as other antioxidants in this round of experiments, the researchers note that their AR extracts were not completely pure, which could have reduced their effectiveness. Also, the researchers used a blend of different ARs that had different molecular structures. Future work looking at different types of ARs will reveal whether an individual AR type is more or less effective than conventionally-used antioxidants.
“We’re trying to identify natural antioxidants that are consumer-friendly, safe, and effective,” says Elder. “We hope that one day this work will lead to ARs being available on the market and provide more options for the food industry to use.”
The research appears in Food Chemistry. The US Department of Agriculture National Institute of Food and Agriculture Federal Appropriations funded this work.
Source: Penn State