Now, if you haven't heard the term, that’s okay. If you have, it clearly means you are familiar enough with wine. In essence, carbonic maceration is a winemaking technique using carbon dioxide that’s commonly applied to produce light and medium bodied red wines in Beaujolais, one of my favorite regions. Now, the use of the process in coffee and in wine aren’t exactly identical. In full carbonic maceration for wine, grapes are placed in vats, then sealed and filled with CO2 to remove oxygen.
Here are a few pictures of the process at the Worka Chelbesa washing station. Chelbesa is located at 2,100 masl, close to the town Worka in Gedeb. Chelbesa is the largest growing area in Gedeb, with a total area of 1240 hectares of coffee farms. This station buys cherries from around 170 farmers all located in the area with average farm size ranging from 0.5 to 2 hectares and altitude ranging from 1,900 t0 2100 meters. Below are few photographic examples from the past harvest.
Cherries are delivered daily by producers and cherries are inspected with quality cherry approved and defects rejected.
After the coffee is depulped, the cherries are submerged underwater and with the weight of concrete and the cherries themselves, it allows them to stay under water producing a yeast fermentation along in a relatively anaerobic environment, rich in CO2. This process lasts for 96 hours and the result is a softer, wine-like acidity with balanced fruits & florals.
After the 96 hour fermentation period, the coffee is transferred to raised beds and dried for up to 2 weeks.
The birth of the Expressive Juice
The man credited for the discovery of carbonic maceration is the French Scientist Michel Flanzy. He began to experiment with the process in 1934 as a preservation technique, but it didn’t quite pick up in popularity until the 1960’s when a chemist by the name of Jules Chauvet, from Beaujolais, created the Semi Carbonic technique. In this technique, whole clusters of grapes are put into wooden, cement, or steel vessels without the addition of CO2. The berries at the bottom are crushed under the weight of those at the top. They undergo a yeast fermentation, which creates carbon dioxide in addition to alcohol. Meanwhile, berries toward the middle and top remain intact and undergo intracellular fermentation. In the 1980’s a group known today as the Gang of Four: Marcel Lapierre, Guy Breton, Jean Foillard and Jean-Paul Théneve sought a return to the styles of wine typified by the generation before them. These wines contained native yeasts and fewer additives, created before pesticides and chemicals became the standard. They called it "vin nature" which, in French, has a bit of a different meaning than simply natural wine. It's more "plain wine," reflecting the idea that nothing—or very little—has been added to the wine. At the time, they were deemed to be heretics but with the support of American wine importer Kermit Lynch, they proved that Gamays were indeed beautiful, complex and dynamic wines which are otherwise known as “Expressive Juice”.
Curiosity & The Smell of Wonder
So now that we’ve covered some of the process and history of Carbonic Maceration, now comes the question- is this coffee a true byproduct of Carbonic Maceration and is it good? The technique that SNAP applied is akin to the beaujolais Natural Carbonic Maceration which isn’t a full Carbonic Maceration process but nets similar results. The real question for us at Metric is- why? The truth is, some of the best results on the cupping table come from your standard process coffees which begs the question- why even bother?
For us, exploring new ideas in coffee processing is what helps us better understand the diverse spectrum of potential flavor coffee has. Our goal as a sourcing and roasting company is to connect with both existing and new producing partners in procuring the very best coffees this season has to offer. For the most part, they all tend to be washed coffees processed under the most basic or traditional of ways. Still, we know that there are still so many unknowns in coffee processing, so much potential for improvements. Feeding into our curiosity is the only way we can learn about how malleable coffee can be.
The Same Difference
At the same time, historically, we have understood the similarities and differences between coffee and wine with one of them being variety vs varietal. In wine, Variety can refer to either the grape itself (Malbec, Chardonnay, Pinot Gris), or to the style or kind of wine, as in red, white, or sparkling, etc. Varietal is used to describe a wine made from a single variety of grape. So, a glass of Chardonnay would be a varietal wine, made from Chardonnay variety grapes. In specialty coffee, we often see these terms being confused. Varietal is often used synonymously with variety, even when the plant itself is a cultivar or a hybrid, causing even more confusion.
We are beyond excited to be offering this wonderful example of coffee that explores the possibilities of using a traditional wine technique in a non traditional way. In the cup, you can expect the usual suspects- compelling acidity, great mouthfeel and lots of tropical fruits that make for yet another stellar offering from Ethiopia. In particular, this coffee demonstrates intense floral aromatics like lavender and jasmine. Can we say it’s insanely unique, no. Was it worth exploring and feeding our curiosity- absolutely! We will continue to support producers that explore new ways to do their craft, and we will always be excited to share that process with you.