Diverse yeast population may play an important role in the characteristics of chocolate and coffee from different parts of the world, revealed researchers. In comparison to the yeasts found in vineyards around the world, those associated with coffee and cacao beans show much greater diversity, the findings showed.
"Our study suggests a complex interplay between human activity and microbes involved in the production of coffee and chocolate," said Aimee Dudley of the Pacific Northwest Diabetes Research Institute in Seattle, US. "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," Dudley noted.
‘Diverse yeast population may play an important role in the characteristics of chocolate and coffee from different parts of the world.’
Coffee and cacao trees originally grew in Ethiopia and the Amazon rain forest. They are now widely cultivated across the 'bean belt' that surrounds the equator. After they are picked, both cacao and coffee beans are fermented for a period of days to break down the surrounding pulp. This microbe-driven process also has an important influence on the character and flavor of the beans.
To explore further, the researchers bought unroasted coffee and cacao beans grown in Central and South America, Africa, Indonesia or the Middle East and isolated the associated yeast in their Seattle laboratory. Genetic analysis of those yeast strains revealed that yeasts from coffee and cacao beans were substantially more diverse than the wine yeasts.
Interestingly, the genetic signatures of the yeast strains strongly clustered according to the geographic origin of the beans, the study said. In fact, this association was so strong that they were able to accurately determine the origin of the beans solely from the DNA sequences of their associated yeasts, Dudley said.
The findings appeared in the journal Current Biology
. The findings showed that the yeast strains associated with coffee and cacao have multiple, independent origins. The researchers believe that the findings could lead to improvements in chocolate and coffee.