Is that chocolate as good as it looks? Scientists develop cocoa quality test

Are you paying more for that 'luxury' chocolate bar? You may be dismayed to learn that it's not uncommon for the cocoa to be 'watered down' with lower quality beans, according to food scientists.

Luckily, there is now an answer. Researchers from the US Department of Agriculture, Nanjing University in China and the Cocoa Research Centre in Trinidad have discovered a DNA test for cacao beans that promises to weed out any below-par chocolate.

The study, lead by Dapeng Zheng from the US Sustainable Perishable Crops Laboratory (part of the Dept. of Agriculture), notes that high-grade cocoa is often mixed in with cocoa from worse quality beans at some point in the manufacturing process, and that many of the 'premium' bars, sauces and truffles that we eat may contain a varied quality of cocoa.

Until now, genetic quality-testing methods that have been used on other foods haven't worked on cacao beans. But Zheng's team was able to isolate a set of DNA 'markers' known as SNPs which act as a genetic fingerprint for differnt species of beans - meaning it's now a lot easier to tell the good from the bad.

"To our knowledge, this is the first authentication study in cacao using molecular markers," the researchers said.

The genome of the most common cacao varieties were fully sequenced last summer. Ecuador, which is one of the world's largest bean producers, blends high-yeilding red-podded beans with better quality green-podded beans.

According to the research, 'the ability to authenticate premium and rare varieties would encourage growers to maintain cacao biodiversity rather than depend on the most abundant and easiest to grow trees.'

The chocolate industry is worth more than £100billion a year worldwide.