Nav: Home

You can thank diverse yeasts for that coffee and chocolate

March 24, 2016

Humans have put yeast to work for thousands of years to make bread, beer, and wine. Wild strains of yeast are also found in the natural fermentations that are essential for chocolate and coffee production. But, as new genetic evidence reported in the Cell Press journal Current Biology on March 24 shows, the yeasts associated with coffee and cacao beans have had a rather unique history.

In comparison to the yeasts found in vineyards around the world, the new work shows that those associated with coffee and cacao beans show much greater diversity. The findings suggest that those differences may play an important role in the characteristics of chocolate and coffee from different parts of the world.

"Our study suggests a complex interplay between human activity and microbes involved in the production of coffee and chocolate," says Aimée Dudley of the Pacific Northwest Diabetes Research Institute in Seattle. "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."

Coffee and cacao trees originally grew in Ethiopia and the Amazon rainforest. 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.

Dudley and her colleagues wanted to know where the yeasts in these human-associated fermentations came from. Had coffee- or cacao-specific yeast strains been unknowingly transported along with the plants? Or, do particular regions of the world harbor novel yeast populations?

To find out, 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. In fact, Dudley says, 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.

The findings show that the yeast strains associated with coffee and cacao have multiple, independent origins. In other words, not all coffee strains are related, nor are all cacao strains. What's more, the yeast strains associated with coffee or cacao in specific places appear to be hybrids that resulted from the mixing of strains from different parts of the world. In fact, one of those strains is closely related to the yeast used to make wine.

"The ancient and continuing global traffic in yeasts associated with wine fermentation may have set the stage for subsequent mingling and admixture events that gave rise to the yeasts that are now associated with the production of coffee and chocolate," Dudley says.

The researchers say the findings could lead to improvements in chocolate and coffee. Studies of wine production have shown that the yeasts associated with fermentation significantly influence the properties of the wine, including its flavor and aroma.

"Given that the yeast strains associated with coffee and cacao fermentations are substantially more genetically diverse than the wine strains, they could play an even larger role in the properties of coffee and cacao produced in different regions of the globe," Dudley says.
-end-
This work was funded by a strategic partnership between the University of Luxembourg and the Institute for Systems Biology and by a National Institutes of Health grant.

Current Biology, Ludlow et al.:"Independent Origins of Yeast Associated with Coffee and Cacao Fermentation" http://dx.doi.org/10.1016/j.cub.2016.02.012

Current Biology (@CurrentBiology), published by Cell Press, is a bimonthly journal that features papers across all areas of biology. Current Biology strives to foster communication across fields of biology, both by publishing important findings of general interest and through highly accessible front matter for non-specialists. Learn more at http://www.cell.com/current-biology. To receive Cell Press media alerts, contact press@cell.com.

Cell Press

Related Chocolate Articles:

Cocoa & chocolate are not just treats -- they are good for your cognition
In a recent review published in Frontiers in Nutrition, Italian researchers examined the available literature for the effects of acute and chronic administration of cocoa flavanols on different cognitive domains.
Eating chocolate may decrease risk of irregular heartbeat
Consuming moderate amounts of chocolate was associated with significantly lower risk of being diagnosed with atrial fibrillation (AF)--a common and dangerous type of irregular heartbeat--in a large study of men and women in Denmark led by researchers at Harvard T.H.
Milk versus dark chocolate: A scientific showdown (video)
Valentine's Day is nearly here. Whether you're spending it with your significant other or flying solo, chocolate is often in the mix.
Pigs and chocolate: Using math to solve problems in farming
Improving cocoa yields for the chocolate industry, estimating the quality of meat in pigs and refining the design of a hydroponics system, were three farming challenges tackled by academics at a recent workshop hosted by the University of Bath's Institute for Mathematical Innovation.
Scientists discover way to make milk chocolate have dark chocolate health benefits
Dark chocolate can be a source of antioxidants in the diet, but many consumers dislike the bitter flavor.
Belgian researchers check quality of chocolate with ultrasound
The quality of Belgium's famous chocolate largely depends on the crystals that form during the hardening of the chocolate.
Social engineering: Password in exchange for chocolate
It requires a lot of effort and expense for computer hackers to program a Trojan virus and infiltrate individual or company computers.
Creating a reduced-fat chocolate that melts in your mouth
Chocolate is divinely delicious, mouthwateringly smooth and unfortunately full of fat.
You can thank diverse yeasts for that coffee and chocolate
Humans have put yeast to work for thousands of years to make bread, beer, and wine.
Fungus that threatens chocolate forgoes sexual reproduction for cloning
A fungal disease that poses a serious threat to cacao plants -- the source of chocolate -- reproduces clonally, Purdue University researchers find.

Related Chocolate Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Digital Manipulation
Technology has reshaped our lives in amazing ways. But at what cost? This hour, TED speakers reveal how what we see, read, believe — even how we vote — can be manipulated by the technology we use. Guests include journalist Carole Cadwalladr, consumer advocate Finn Myrstad, writer and marketing professor Scott Galloway, behavioral designer Nir Eyal, and computer graphics researcher Doug Roble.
Now Playing: Science for the People

#529 Do You Really Want to Find Out Who's Your Daddy?
At least some of you by now have probably spit into a tube and mailed it off to find out who your closest relatives are, where you might be from, and what terrible diseases might await you. But what exactly did you find out? And what did you give away? In this live panel at Awesome Con we bring in science writer Tina Saey to talk about all her DNA testing, and bioethicist Debra Mathews, to determine whether Tina should have done it at all. Related links: What FamilyTreeDNA sharing genetic data with police means for you Crime solvers embraced...