Scientists make ‘healthy’ milk chocolate by adding antioxidant-rich peanut skins and coffee grounds 

Adding peanut skins to milk chocolate would make it healthier, suggests a new study.

Researchers found that recycled food waste – such as peanut skins, coffee grounds and tea leaves – can be used to ‘supercharge’ milk chocolate with the same antioxidant health benefits as dark chocolate.

Milk chocolate, used in some of the world’s favorite sweet snacks – including M&Ms and Cadbury Eggs – does not have the molecules known as phenolic compounds, which makes dark chocolate more bitter, but far healthier.

Combining the antioxidant-rich  

MIlk chocolate is preferred by many consumers but is less healthy than its antioxidant-rich cousin dark chocolate – unless it’s enhanced with phenolic compounds from peanut skins

‘The idea for this project began with testing different types of agricultural waste for bioactivity, particularly peanut skin,’ study co-author Dr Lisa Dean, of United States Department of Agriculture – Agricultural Research Service, said. 

‘Our initial goal was to extract phenolics from the skins and find a way to mix them with food.’

Around 40 million metric tons of peanuts are produced every year, over 60 per cent of which are roasted to make peanut butter and sweets.

The papery red skins that encase the nut inside its shell are tossed aside during the roasting process.

While thousands of tonnes of peanut skins go to waste, around 15 percent of each skin’s weight is phenolic compounds, meaning they are a ‘gold mine of antioxidant bioactivity.’

Antioxidants have anti-inflammatory health benefits, while keeping food products from spoiling and may prevent or delay cell damage.

‘Phenolics are very bitter, so we had to find some way to mitigate that sensation,’ said Dr Dean. 

‘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.’

The research team ground peanut skins into a powder and used 70 percent ethanol to extract the phenolic compounds.

Maltodextrin, a common food additive, was then added to the phenolic powder, making it easier to blend with milk chocolate products.

Chocolate squares containing between 0.1 percent and 8.1 percent of the phenolic mixture were created by the researchers.

A ‘trained sensory panel’ was then asked to taste each one, in the hope they would not be able to taste the healthy additive.

Taste testers detected the compound above 0.9 percent concentration, a good compromise between taste, texture and bioactivity, the researchers said.

Over half the lucky chocolate tasters preferred the milk chocolate with added phenolics to the untouched chocolate milk.

Dr Dean said: ‘While these results are very promising, peanuts are a major food allergy concern.

‘We tested the phenolic powder made from the skins for presence of allergens, and while none were detected, a product containing peanut skins should still be labelled as containing peanuts,’ she explained. 

The same method could be used to extract phenolics from coffee grounds and tea leaves, the researchers found.

Any waste from the process, including the lignin and cellulose, can be used in animal feeds as roughage.

‘We plan to further explore the use of peanut skins, coffee grounds and other waste products into additional foods,’ Dr Dean said. 

‘In particular whether the antioxidants in peanut skins extend the shelf life of nut butters, which can go rancid quickly because of their high fat content.’

While their super-charged chocolate milk has yet to hit shelves, better milk chocolate on supermarket shelves is coming soon, the researchers hope.

The findings were due to be presented at the American Chemical Society virtual meeting and expo.