The unique quality that gives Black Ivory coffee its rich, chocolatey taste may be hidden deep within the digestive systems of the largest land animals on Earth. According to a recent study of the microbes residing in the intestines of Asian elephants (Elephas maximus), researchers have identified specific groups of bacteria that likely break down compounds that would otherwise render coffee bitter.
"Our earlier research indicated that Gluconobacter was the predominant genus in the intestines of civet cats, and it may generate volatile compounds from the coffee beans, implying that microbial metabolism plays a role in the coffee's aroma," states genomicist Takuji Yamada from the Institute of Science Tokyo in Japan. "These discoveries prompted the inquiry of whether the gut microbiome of elephants similarly affects the flavor of Black Ivory coffee."
Black Ivory coffee ranks among the priciest coffees globally, surpassing kopi luwak – coffee processed through civets (which are not actually cats).
It is produced exclusively at a single elephant sanctuary in Thailand, where certain elephants are given unprocessed coffee cherries. Workers at the sanctuary later gather the coffee beans that have been digested and excreted by the elephants, then clean and roast them for human enjoyment.
The coffee is celebrated for its taste, often regarded as exceptional. After finding that the gut bacteria of civets might influence the flavor of kopi luwak, Yamada and his team were curious if a similar process was at work in shaping the flavor profile of Black Ivory coffee.
They conducted their research not by examining the coffee beans, but by directly analyzing elephant feces to survey the gut microbes. They collected samples from six elephants in the sanctuary – three that had consumed coffee cherries and three that had not, serving as a control group.
The only variation in their diets was a treat given to the coffee-eating elephants, which included bananas, coffee cherries, and rice bran. Therefore, if there were any differences in their gut microbiome, it was likely due to this extra snack.
The bitterness in coffee is partly due to a compound known as pectin, which is present in plant cell walls, along with cellulose. When coffee is roasted, both pectin and cellulose decompose into compounds that taste bitter. By sequencing the fecal samples, researchers discovered that elephants that digest coffee have a significantly higher number of gut microbes that help break down pectin and cellulose. Some bacterial species were completely absent in the control group. The researchers also utilized previously published data to compare the microbiomes of coffee-digesting elephants with those of cattle, pigs, and chickens, in an effort to identify any other possible coffee digesters.
Although some relevant bacterial species were identified, only the guts of the elephants contained the complete set of tools necessary for breaking down pectins and cellulose.
A study from 2018 revealed that Black Ivory coffee contains significantly less of a compound called 2-furfuryl furan compared to regular coffee beans. This compound is one of the bitter substances formed from the breakdown of pectin during roasting.
The recent analysis of elephant microbiomes indicates that the partial digestion of coffee cherries aids in removing the components of coffee beans that become bitter during roasting, leading to a much more enjoyable flavor profile. The next phase will involve examining the beans themselves. "Our findings may reveal a potential molecular mechanism through which the gut microbiota of Black Ivory coffee elephants influences the flavor of Black Ivory coffee," Yamada states. "Further experimental validation is necessary to test this hypothesis, including a biochemical analysis of coffee bean components before and after they pass through the elephant's digestive system."