Chocolatiers use yeasts to ferment the cocoa when making their tasty confections, which helps guard against the occasional bad-tasting batch. Those same yeasts can also be used to alter the aroma, providing a new means of making designer chocolate tailored to match your favourite flavours.
Before cocoa beans are ground up, purified, melted, and combined with milk, they're tossed in a box or in a pile on the farm where they are harvested. In that box is microscopic life. Bacteria and yeasts ferment the beans slightly. This usually doesn't hurt the chocolate, but it does mean there is variation in flavour.
Manufacturers of chocolate bars don't care for variation in flavour. When people pick up a Snickers bar, they have expectations as to how it will taste. Smaller manufacturers don't have the same brand recognition, but they do have a signature flavour that can be thrown off by batches of chocolate that have been fermented at different farms with different microorganisms.
To eliminate the occasional badly-fermented batch, a team of Belgian researchers started looking for a microbial "starter," that would — in the atmosphere of the boxes in which the beans are kept — out-compete other yeasts and take over the box. They found that this starter often improved the taste of the resulting chocolate.
According to a paper published in July in Applied and Environmental Microbiology, "Analysis of the resulting chocolate shows that some 31 of the cocoa batches that were fermented with specific starter cultures yielded superior chocolate." It should also make chocolate more uniform.
But even after roasting and processing, the beans retained different flavours from different strains of yeast. This could give chocolatiers a new way to tinker with the flavour of their chocolate, according to the group's latest paper that just appeared in Applied and Environmental Microbiology. Not only can they work with a variety of ingredients to make a signature bar, they can review a variety of yeasts with with to flavour the cocoa beans. They could even come up with a signature microbial cocktail to flavour their chocolate.
So this could be the start of more uniform chocolate bars, or the beginning of a new variation on existing flavours.