Peanut Waste Makes Milk Chocolate Healthier

Researchers save discarded food products and increase candy nutrition.

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Peanuts are heated microwave oven, so their skins cracked.
The papery skins of peanuts are usually thrown away. vavlt / Getty Images

Researchers are working on making a more healthy milk chocolate by adding peanut waste. Their new combination would increase the nutrition quotient of a popular treat and also give a new life to discarded food products.

The research was presented Aug. 18 at a meeting of the American Chemical Society

Traditionally, dark chocolate is the healthier chocolate choice. It’s full of a plant chemical called flavanols that may protect the heart by lowering blood pressure and decreasing the risk of heart disease. Milk chocolate tastes sweeter, but isn't as healthy.

“My study was to develop applications for a functional food ingredient made from peanut skins,” Lisa Dean, research food technologist at North Carolina State University and the project’s principal investigator, told Treehugger. “Due to the allergenicity of peanuts, it was necessary to only use foods that people commonly associate with peanuts. As five of the top 10 most popular candy bars in the U.S. contain peanuts and the chemical compounds in the ingredient are similar to those in dark chocolate, milk chocolate seemed to fit the criteria. Milk chocolate is also liked better by consumers than dark chocolate.”

When manufacturers roast peanuts during processing while making candy, peanut butter, and other products, they have no use for the red peanut skins. Thousands of tons of papery peanut skins are thrown away annually. 

“They are a disposal problem for the peanut industry and it would be a great benefit to the industry to find uses for them,” Dean says. “The main goal was to find a way to use the ingredient made from the peanut skins.”

Because peanut skins contain 15% phenolic compounds, they have antioxidant benefits, the researchers say. But the compounds are very bitter, so the team had to find a solution to soften that taste. Milk chocolate proved to be a sweet solution.

Different Types of Chocolate

Still life with white, dark and milk chocolate
Dark chocolate has the most cocoa and is believed to have the most health benefits. Luka / Getty Images

A 2020 industry report found that the chocolate market is expected to reach $171.6 billion globally by 2026. Chocolate is the most popular sweet treat in the world.

The key ingredient in chocolate is cocoa in the form of liquor or butter. Cocoa comes from roasted beans from the cacao tree (Theobroma cacao), which is native to the Amazon river basin and tropical areas of Central and South America.

The various types of chocolate depend primarily on the amount of cocoa they contain. According to the U.S. Food and Drug Administration (FDA), white chocolate has to have a cocoa butter content of at least 20%. Milk chocolate has to have a minimum of 10% chocolate liquor and dark chocolate has to have at least 35% chocolate liquor by weight to be called semisweet or bittersweet. Most bittersweet dark chocolate bars have a cocoa content of 50% and up.

Dark chocolate has a more bitter taste than milk chocolate. That’s due to the phenolic compounds, and also because it has less fat and sugar than milk chocolate. Dark chocolate is also more expensive than other chocolates because of the higher amount of cocoa. Adding nutritional waste to milk chocolate can provide similar benefits for less cost, the researchers say. 

How It Works

In order to create their powered-up milk chocolate, Dean’s team from the U.S. Department of Agriculture's (USDA's) Agricultural Research Service collected discarded skins from peanut companies. They ground them into powder, and extracted the phenolic compounds. Leftover materials can be used in animal feed, the researchers said.

The phenolic powder was combined with maltodextrin, a common food additive made from vegetable starch, which made it easier to mix with the milk chocolate. They made squares of chocolate with varying levels of phenolics ranging from 0.1% to 8.1% for trained taste testers to try.

They found that 0.8% was a good mix of phenolics while not losing texture or taste. Researchers said that more than half of the testers actually preferred the 0.8% phenolic-filled milk chocolate over plain milk chocolate.

The researchers tested the phenolic powder for allergens and found none. But they said any chocolates that contain the power should still be labeled as containing peanuts because the nuts are such a major trigger for food allergies.

It will be some time before the chocolate will be commercially available. Next up, researchers are studying the benefits of other antioxidant-filled compounds such as coffee grounds, used tea leaves, and other food leftovers.