The yeasts used in the production of alcohol, like wine, are relatively stable in terms of their genetic history. In contrast, yeasts associated with the processing of coffee and cacao beans have shown far greater variation. Scientists think the variation leads to yeasts of slightly different varieties being found in different parts of the world and that these account for slightly different forms and flavors.
The findings also highlight the role of human activity in shaping food production and the selection of the appropriate types of yeast, and also with the transportation of yeasts around the world through the cultivation of plants.
With the latter issue, both coffee and cacao originated in Ethiopia and the Amazon rainforest. However, they are now grown in a range of countries.
Once picked, both cacao and coffee beans are fermented for a period of days. This is to process the surrounding pulp. This process, driven by the yeast, influences the character and flavor of the beans.
Yeasts are single-celled fungi. Several yeast species can convert carbohydrates to carbon dioxide and alcohols, forming the basis of the modern drinks and bread industries.
Research into the yeasts has found the fungi from coffee and cacao beans are far more diverse than the wine yeasts. Another finding of interest is that yeast strains varied according to the geographic origin of the beans. Many of these strains were hybrids, as a result of mixing of strains from different parts of the world.
Explaining this further to The Smithsonian, lead researcher Aimée Dudley, a geneticist at the Pacific Northwest Diabetes Research Institute, said: “The first really interesting thing we noticed was that they were all very different from each other. So a coffee strain from Colombian coffee was very similar to other Colombian strains, but it was really different from Yemeni coffee.”
This process is likely to continue through the expansion of global traffic. The net effect should be a further diversification of yeast and further regionalization of flavors. This is something that could benefit consumers.
The research findings have been published in the journal Current Biology. The research is headed “Independent Origins of Yeast Associated with Coffee and Cacao Fermentation.”
