Fun with fermentations: Black coffee in bed with help from microbes

Australia is, for reasons I’ll never understand, a country of coffee snobs, with their baristas and their 20-minute preparation times and the $4.50 a cup.

No Tim Hortons here (sadly, the co-founder of the venerable Canadian chain passed away today).

According to research published February 1 in the journal, Applied and Environmental Microbiology, when 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.

“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 microorganisms 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 microorganisms 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 Nestlé Research. “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.

Fermentations: A microbiological orgasm for food and drink

Third-year university in 1983, and things started to click.

I was bored, angst-ridden and wondering what am I doing here.

home-made preserves for the winter isolated on white background

home-made preserves for the winter isolated on white background

Then I took an industrial microbiology class.

Fermentations.

(And no, Michael Pollan didn’t invent bragging about fermentations either).

The next year I took a virology class and suddenly realized: we humans are hosts on a microbiological planet.

The way these bugs move genes around, invade others, and have been crucial to the evolution of humans has intrigued me ever since.

Kim Painter of USA Today writes that Americans used to find yogurt yucky. But the creamy dairy food long ago joined beer and cheese on the list of our favorite things produced by fermentation — an ancient preservation process in which bacteria transform food and drink, creating new flavors and, many consumers believe, enhanced health benefits.

So maybe it’s not surprising that thousands of people now show up at fermentation festivals around the country to make sauerkraut and sample kombucha teas, Korean kimchi and Japanese natto. The same folks flock to pop-up “kraut mobs” and study books such as Wild Fermentation and The Art of Fermentation, both by the movement’s guru, Sandor Katz.

“I would say that virtually every event I do these days is at capacity, and I’m not accepting every invitation. I can’t physically do it,” Katz says. He spoke from China, where he was on a quest for more fermentation wisdom.

Fermentation is the hottest trend in plant-based eating, according to recent survey of registered dietitians by The Monday Campaigns, a non-profit organization that promotes healthy lifestyles.

Jeremy Ogusky, a Boston pottery maker, sees it firsthand as founder of Boston Ferments, the host group for a summer festival that drew a few hundred people four years ago and 14,000 this year.  “It’s just grown every year,” he says. “It’s kind of crazy.”

And what about safety, especially for foods fermented at home?  After all, the process typically requires leaving jars of foodstuffs sitting out for weeks, without the final sanitizing steps used in standard canning. (Heat processing can be added for some foods, but purists generally frown on that.)

The history of fermentation, especially with vegetables, is mostly reassuring. When properly done, fermentation produces acids that kill most worrisome microorganisms, says my barfblog.com friend, who also shares a love of fermentations, Benjamin Chapman, an associate professor and food safety extension specialist at North Carolina State University.

“We have lots of data showing that if you get the correct pH drop, the correct acidity level, you can create a really, really low risk product,” he says. But he says risks are not zero, and some cases of home fermenters making mistakes and creating unsafe foods have been reported. That’s why he urges people to use only long-tested recipes and techniques.


 

From the duh files: Slow lorises and aye-aye lemurs prefer alcohol over water

Biologists at Dartmouth College in New Hampshire discovered that when faced with the choice of various sugary substances laced with different alcohol concentrations, the loris and aye-ayes repeatedly chose the most alcoholic solution.

drunk.lemursIn fact the researchers report in the Royal Society Open Science, the aye-ayes loved the concoction so much they enthusiastically searched for more, while the slow loris displayed “a relative aversion to tap water”.

Interestingly, the alcohol did not seem to affect the creatures.

Samuel Gochman, a biology student at Dartmouth, said: “No signs of inebriation were observed,” reports The Guardian.

The aye-aye’s tolerance to alcohol may be explained by a genetic mutation, which speeds up the rate alcohol is broken down.

“The results indicate that the mutation might (have) a preference for alcohol,” Gochman said.

Massachusetts fermenter known for its unpasteurized tempeh wins award

According to the Berkshire Eagle, lacto-fermented vegetables are all the rage. But I’d be concerned about how food safety is managed.

Hosta Hill, a Berkshires-based maker of lacto-fermented vegetables and unpasteurized tempeh, has been honored with a 2016 Good Food Award for its Gochu Curry Kraut, a variation on traditional sauerkraut featuring Indian and Korean influences.IMG_9896

“We’re thrilled to be recognized for the second consecutive year by the Good Food Awards,” Elling, a Berkshires native and graduate of Monument Mountain High School in Great Barrington, said in the press release announcing the award. “We love that they say we ‘celebrate the kind of food we all want to eat: tasty, authentic and responsibly produced’ because it acknowledges the complete method behind the meal. To have our handmade ferments, featuring sustainably grown ingredients from right here in the Berkshires, reach a national audience and be mentioned in the same sentence as so many of these other great companies is an incredible honor.”

Does responsibly produced include vetting their starter culture suppliers and asking them to test their products for Salmonella. And telling the folks who use the unpasteurized tempeh that they need to handle it like raw meat?