Milk chocolate is a consumer favorite worldwide, prized for its sweet flavor and creamy texture. This confection can be found in all types of treats, but it isn't exactly health food. In contrast, dark chocolate has high levels of phenolic compounds, which can provide antioxidant health benefits, but it is also a harder, bitter chocolate. Recently, researchers report a new way to combine milk chocolate with waste peanut skins and other wastes to boost its antioxidant properties.
"The idea for this project began with testing different types of agricultural waste for bioactivity, particularly peanut skins," says Lisa Dean, Ph.D., the project's principal investigator. "Our initial goal was to extract phenolics from the skins and find a way to mix them with food."
When manufacturers roast and process peanuts to make peanut butter, candy and other products, they toss aside the papery red skins that encase the legume inside its shell. Thousands of tons of peanut skins are discarded each year, but since they contain 15% phenolic compounds by weight, they're a potential goldmine of antioxidant bioactivity. Not only do antioxidants provide anti-inflammatory health benefits, but they also help keep food products from spoiling.
"Phenolics are very bitter, so we had to find some way to mitigate that sensation," Dean says. In fact, the natural presence of phenolic compounds is what gives dark chocolate its bitterness, along with less fat and sugar compared to its cousin milk chocolate. Dark varieties are also more expensive than milk ones because of their higher cocoa content, so the addition of a waste like peanut skins provides similar benefits for a fraction of the price. And peanut skins are not the only food waste that can enhance milk chocolate in this way; the researchers are also exploring the extraction and incorporation of phenolic compounds from used coffee grounds, discarded tea leaves and other food scraps.
To create their antioxidant-boosted milk chocolate, Dean and her team of researchers at the U.S. Department of Agriculture's (USDA's) Agricultural Research Service worked with peanut companies to obtain the peanut skins. From there, they ground the skins into a powder, and extracted the phenolic compounds with 70% ethanol. The lignin and cellulose left behind can be used in animal feed as roughage. They also worked with local coffee roasters and tea producers to obtain used coffee grounds and tea leaves, using a similar methodology to extract the antioxidants from those materials. The phenolic powder is then combined with maltodextrin, a common food additive, to make it easier to incorporate into the final milk chocolate product.
While these results are very promising, Dean and team also acknowledge that peanuts are a major food allergy concern. They tested the phenolic powder made from the skins for presence of allergens, and while none were detected, they say that a product containing peanut skins should still be labeled as containing peanuts.
Next, the researchers plan to further explore the use of peanut skins, coffee grounds and other waste products into additional foods.
(Source: Agriculture and Food News, ScienceDaily. www.sciencedaily.com)
