Researchers have found a way to make chocolate more flavourful and nutritious with greater levels of anti-oxidants.

Chocolate is known to have health benefits. It can potentially lower blood pressure and cholesterol and reduce stroke risk.

Cocoa undergoes several steps before it takes shape as a candy bar. Workers cut down pods from cocoa trees, then split open the pods to remove the white or purple cocoa beans.

They are fermented in banana-lined baskets for a few days and then set out to dry in the sun. Roasting, the next step, brings out the flavour.

But some of the healthful polyphenols (antioxidants) are lost during the roasting process, so the researchers wanted to figure out a way to retain as much of the polyphenols and good flavours as possible.

"We decided to add a pod-storage step before the beans were even fermented to see whether that would have an effect on the polyphenol content," said Emmanuel Ohene Afoakwa at the University of Ghana.

"This is not traditionally done, and this is what makes our research fundamentally different. It`s also not known how roasting affects polyphenol content," Afoakwa said.

Afoakwa`s team divided 300 pods into four groups that were either not stored at all or stored for three, seven or 10 days before processing.

This technique is called `pulp preconditioning`. After each storage period passed, fermentation and drying were done as usual. He said that the seven-day storage resulted in the highest antioxidant activity after roasting. To assess the effects of roasting, the researchers took samples from each of the storage groups and roasted them at the same temperature for different times. The current process is to roast the beans for 10-20 minutes at 120-130 degrees Celsius. Afoakwa`s team adjusted this to 45 minutes at 116 degrees Celsius and discovered this slower roasting at a lower temperature increased the antioxidant activity compared to beans roasted with conventional method.

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