26/03/2016 9:58 AM AEDT | Updated 15/07/2016 12:51 PM AEST

The Kinda Gross Bacteria Fermentation Process Vital For Chocolate

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Rich cacao beans dry and ferment in preparation to make chocolate.

Fermentation is about as divisive as food trends come. There are those who love the mysterious, gassy world of bacteria and those who think a scoby is something you should spit out.

But chocolate, well, almost everyone likes chocolate.

It may surprise you then to discover chocolate (and coffee) would not exist without fermentation, and new research shows the bugs that make it can be traced back to the dawn of civilisation.

The study, by the Pacific Northwest Diabetes Research Institute in Seattle, looked at the wild yeast that fermented cacao and coffee beans around the world.

When cacao beans are picked, they're surrounded by a slightly sweet fruit pulp. Yeasty bacteria eats the pulp to create a gassy, gooey ferment that turns a bitter little cacao bean into something that more closely resembles chocolate's most important ingredient -- coco.

Researchers bought unroasted coffee and cacao beans from Central and South America, Africa, Indonesia and the Middle East to look at their fermentation yeast under the microscope.

"Our study suggests a complex interplay between human activity and microbes involved in the production of coffee and chocolate," researcher Aimée Dudley said.

"Humans have transported and cultivated the plants, but at least for one important species, their associated microbes have arisen from transport and mingling in events that are independent of the transport of the plants themselves."

The results, published in Current Biology, found chocolate-making yeast from different regions had distinctly different DNA -- allowing researchers to accurately guess where a bean came from based on its yeast.

They also believe these yeasts are what gives chocolate a distinct, regional flavour.

So there you have it, happy 'yeaster' everybody!