Nav: Home

Microbes help make the coffee

February 01, 2019

Washington, DC - February 1, 2019 - When it comes to processing coffee beans, longer fermentation times can result in better taste, contrary to conventional wisdom. Lactic acid bacteria play an important, positive role in this process. Other species of microbes may play a role in this process as well, but more research is needed to better understand their role. The research is published February 1 in Applied and Environmental Microbiology.

"A cup of coffee is the final product of a complex chain of operations: farming, post-harvest processing, roasting, and brewing," said principal investigator Luc De Vuyst, M.Sc., Ph.D., Professor of Industrial Microbiology and Food Biotechnology, Vrije Universiteit Brussel, Brussels, Belgium. "There are several variants of post-harvest processing, among which wet processing and dry processing are the most common." Wet processing--commonly used for Arabica and specialty coffees--is the step that includes fermentation.

"We carried out the research at an experimental farm in Ecuador through a multiphasic approach, encompassing microbiological, metabolomics, and sensory analysis," said Dr. De Vuyst.

Fermentation was of particular importance. During extended fermentation, leuconostocs--a genus of lactic acid bacteria used in the fermentation of cabbage to sauerkraut and in sourdough starters--declined in favor of lactobacilli, said Dr. De Vuyst. Lactic acid bacteria were already present before fermentation, and these acid tolerant lactobacilli proliferated even more during this process.

However, it is challenging to draw a causal link between the microbiota and the volatile compounds in the beans--those compounds that contribute to the coffee's smell - since many of these compounds can be of microbial, endogenous bean metabolism, or chemical origin," said Dr. De Vuyst.

"However, we did see an impact of the microbial communities, in particular the lactic acid bacteria," said Dr. De Vuyst. They yielded fruity notes, and may have "had a protective effect toward coffee quality during fermentation because of their acidification of the fermenting mass, providing a stable microbial environment and hence preventing growth of undesirable micro-organisms that often lead to off-flavors," he said.

"Furthermore, there is a build-up of the fermentation-related metabolites onto the coffee beans, which affects the quality of the green coffee beans and hence the sensory quality of the coffees brewed therefrom," said Dr. De Vuyst.

Dr. De Vuyst emphasized that how each stage of processing influences the taste of coffee remains mostly uncharted. "We were aware of many different micro-organisms during wet coffee fermentation--enterobacteria, lactic acid bacteria, yeasts, acetic acid bacteria, bacilli, and filamentous fungi," said Dr. De Vuyst, but it is still unknown how most bacteria influence this process.

The work was a collaboration between the Vrije Universiteit Brussel, and the Nestlé Research Center. "Nestlé was interested in the fundamental aspects of coffee processing, in particular, the post-harvest processing chain, in order to correlate it with the roasting process and of course the final cup quality," said Dr. De Vuyst.
-end-
The American Society for Microbiology is the largest single life science society, composed of more than 32,000 scientists and health professionals. ASM's mission is to promote and advance the microbial sciences.

ASM advances the microbial sciences through conferences, publications, certifications and educational opportunities. It enhances laboratory capacity around the globe through training and resources. It provides a network for scientists in academia, industry and clinical settings. Additionally, ASM promotes a deeper understanding of the microbial sciences to diverse audiences.

American Society for Microbiology

Related Microbes Articles:

Rye is healthy, thanks to an interplay of microbes
Eating rye comes with a variety of health benefits. A new study from the University of Eastern Finland now shows that both lactic acid bacteria and gut bacteria contribute to the health benefits of rye.
Gut microbes may affect the course of ALS
Researchers isolated a molecule that may be under-produced in the guts of patients.
Gut microbes associated with temperament traits in children
Scientists in the FinnBrain research project of the University of Turku discovered that the gut microbes of a 2.5-month-old infant are associated with the temperament traits manifested at six months of age.
Gut microbes eat our medication
Researchers have discovered one of the first concrete examples of how the microbiome can interfere with a drug's intended path through the body.
Microbes can grow on nitric oxide
Nitric oxide (NO) is a central molecule of the global nitrogen cycle.
Microbes help make the coffee
When it comes to processing coffee beans, longer fermentation times can result in better taste, contrary to conventional wisdom.
Space microbes aren't so alien after all
A new Northwestern University study has found that -- despite its seemingly harsh conditions -- the ISS is not causing bacteria to mutate into dangerous, antibiotic-resistant superbugs.
Nutrient-recycling microbes may feel the heat
While microbial communities are the engines driving the breakdown of dead plants and animals, little is known about whether they are equipped to handle big changes in climate.
Our microbes are starving, and that's a good thing
Our bodies house trillions of microbes, collectively known as the microbiome, which digest food, synthesize vitamins, bolster immune systems, and even maintain mental health.
Classifying microbes differently leads to discovery
Changing the way microbes are classified can reveal similarities among mammals' gut microbiomes, according to a new study published in mBio that proposes an alternative method for classifying microbes to provide insight into human and environmental health.
More Microbes News and Microbes Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

Risk
Why do we revere risk-takers, even when their actions terrify us? Why are some better at taking risks than others? This hour, TED speakers explore the alluring, dangerous, and calculated sides of risk. Guests include professional rock climber Alex Honnold, economist Mariana Mazzucato, psychology researcher Kashfia Rahman, structural engineer and bridge designer Ian Firth, and risk intelligence expert Dylan Evans.
Now Playing: Science for the People

#541 Wayfinding
These days when we want to know where we are or how to get where we want to go, most of us will pull out a smart phone with a built-in GPS and map app. Some of us old timers might still use an old school paper map from time to time. But we didn't always used to lean so heavily on maps and technology, and in some remote places of the world some people still navigate and wayfind their way without the aid of these tools... and in some cases do better without them. This week, host Rachelle Saunders...
Now Playing: Radiolab

Dolly Parton's America: Neon Moss
Today on Radiolab, we're bringing you the fourth episode of Jad's special series, Dolly Parton's America. In this episode, Jad goes back up the mountain to visit Dolly's actual Tennessee mountain home, where she tells stories about her first trips out of the holler. Back on the mountaintop, standing under the rain by the Little Pigeon River, the trip triggers memories of Jad's first visit to his father's childhood home, and opens the gateway to dizzying stories of music and migration. Support Radiolab today at Radiolab.org/donate.