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Gopaulchan and colleagues selected three women-owned farms in Colombia that grow similar strains of cocoa. Two of the farms produced fine chocolate while the third made bulk chocolate. The researchers measured temperature and pH changes in the fermenting beans and took molecular snapshots of microbes present at each stage of the process.

The researchers put together combinations of bacteria and yeasts and fermented small batches of beans in the lab. Ali and a panel of other expert tasters confirmed that the lab-fermented beans had notes of orange blossom, citrus, berry, tropical fruit and flowers characteristic of fine chocolates from the two Colombian farms and a sample from Madagascar. The lab mix was missing caramel, nut and light wood flavors, and had more grassy notes than the fine chocolates did.

Artificially constructed microbe communities might make too much of the aromatic compounds that flavor the fine chocolates, Dudley says. “Humans have a very sharp boundary for what tastes really good and what tastes awful. And the yeast make the amount of those compounds at exactly that boundary of what humans think is palatable.” Messing with the mixes could cross the line.