New Delhi, Oct. 31: Call it a sweet waste-to-health trick.

Scientists have shown that peanut skin extracts, an agricultural waste, may be used to inject some of the nutritional benefits of dark chocolate into milk chocolate without affecting its taste.

Food science specialists at the North Carolina State University in the US have extracted biologically-friendly phenolic compounds from peanut skins, encapsulated them into an edible powder from starchy food such as potatoes or rice, and incorporated them into milk chocolate.

An abundance of evidence accumulating over the past two decades has suggested that dark chocolate through its poly-phenolic constituents is beneficial for health, but some people share an aversion to its extra bitter taste.

Lisa Oehrl Dean and her colleagues investigated peanut extracts as a novel source of antioxidants to enrich milk chocolate. They encapsulated the peanut skin extracts into a starch-sourced substance called maltodextrin to lessen their bitterness and determined through chemical analysis the amount to be added to milk chocolate.

The scientists compared the enriched milk chocolate with unaltered milk chocolate on 80 volunteers and found that both were equally well liked.

"Consumers found the antioxidant fortified milk chocolate to have acceptable flavour," the researchers said, describing their findings in the Journal of Food Science.

"If applied to commercial products, peanut skin extracts would allow consumers to enjoy mild tasting products and have exposure to compounds that have proven health benefits," Dean said in a statement issued through the US-based Institute of Food Technologists.

Several research studies have indicated that antioxidants in dark chocolate may protect people from high blood pressure among other health disorders. Studies by Luc Djousse and his colleagues at the Harvard Medical School have found an overall drop in blood pressure among people who eat more chocolate.

A University of San Diego research team had reported in September this year that dark chocolate can improve the exercise capacity of sedentary people.

And scientists at the National Institute of Mental Health and Neurosciences, Bangalore, had earlier this year independently presented study findings that indicated that dark chocolate with 70 per cent cocoa solid appeared to improve spatial memory in laboratory rats serving as models for Alzheimer's disease.

However, a US National Institutes of Health newsletter cautioned five years ago that despite the evidence in favour of chocolate and biological mechanisms to explain why chocolate is health-friendly, processed chocolate contains other ingredients and the amount consumed could influence health impacts.

"Controlling how much chocolate people eat and tracking them for long periods of time is not an easy task," it said, adding some health tips for people who already consume chocolate. "Eat ask dark a chocolate as you can, avoid, white and milk chocolates, make hot chocolate as unsweetened cocoa, and watch your total calories."

Nutrition specialists also point out that chocolate, even dark chocolate, is laden with calories and consuming too much chocolate could negatively compensate for any benefits from its ingredients.