I was introduced to a process known as carbonic maceration last year while on a trip to Colombia and Nicaragua. When I recently found an offering processed in this style, I had to give it a try. I will say that I was slightly confused with this profile at first, but if you’re into chocolate notes, creamy mouthfeel, like using single origins as espresso, and enjoy a sweeter finish with not too much acidity, this is your bag.
With that said, the offering this week is quickly transitioning from an Ethiopia natural processed coffee (heavy on the fruit attribute) to a Tanzania coffee (creamy, soft, mellow acidity) that has been processed using carbonic maceration, a term lifted from the wine industry. Chris Kornman in Daily Coffee News (and also one of the ‘sourcerers’ of the Tanzania coffee via Royal Coffee, writes about both the processing and the Tanzania coffee;
In the carbonic method for coffee fermentation, first, the coffee cherries are siphoned to remove low-density “floaters,” then added to an airtight tank with a one-way valve, much in the same way as in the anaerobic method. Because the skins of the cherries are left in tact, fermentation may take days or weeks. The varying levels of pressure in the tank create different available sugars and pectins for the microbes to macerate. Near the bottom of the tank, the coffees are gently pressed over time by gravity, whereas cherries near the top of the pile remain unpressed and fermentation will occur slowly and almost entirely inside the skin of the fruit.
Neel Vohora, a veteran coffee producer whose family farms on the slopes of the Ngorongoro caldera in northern Tanzania, has been experimenting with adding water to his carbonic method coffee. After five to seven days in a water-filled carbonic tank, the water becomes saturated with fermenting enzymes and byproducts and begins to foam out the valve. This is the indication for him to end fermentation before pulping the fruit and sending it straight to the drying tables. This coffee tastes very unique, a bridge between methods: ripe berry and grape flavors meet dried dates, browned butter, and maple syrup with a distinct sage-like note.
Don’t wait too long. This batch is basically going to be gone in a few days, but don’t fret, I’m following up with a light and refreshing selection from the Kayanza Province of Burundi. Thereafter we will explore a new arrival from Guatemala, and then head back over to Rwanda for another great coffee from Musasa Mbilima Dukunde Kawa.
So to reiterate, the curation of Mosaic coffees and their limited supply will likely leave you in suspense as to which coffee will be available to you when you place your order. Think of it like trading cards or a box of random extraordinary chocolates – you’re going to get a range of what you expect, and hopefully you find something new that you enjoy.