Ethiopia - Megadu "Cherry Ascension" Lot-H Carbonic Macerated Natural

Brew Guide:

Best Brewed with: Filter

Lightest Roaster Influence: It's a delicate balancing act - super dense, nicely screen beans meet heavier hand processing. We've chosen a relatively fast roast with a slightly softer end, aiming to maximise aromatics and minimise funk. As per!

Best Rested: 4+ weeks

Filter: 62g/L, 96°C when fresh but when well rested you can go down to 91-92°C

Espresso: 18g/48g/18-22s. Excellent soup/turbo

We're tasting: Big maraschino cherry and lavender aromatics alongside pineapple rings. In the cup it's super complex and full - we're getting the syrupy + slightly boozy cherry/marzipan note of crème de cerise, blueberry jam, tinned pineapple, and dried mango, with a touch of milk chocolate. As it cools becoming more complex - we're getting strawberry jam, dark honey, and a warming spiced note akin to rue/passionberry + cloves, with more prominent lavender florals.

Traceability

The Story

It's been a long time since we last explained why we use the word "anoxic" for many of our processing descriptors - but it's worth bringing up at the start of this. All fermentation is anaerobic in its method of respiration - bacteria and yeast do not use oxygen as part of the pathway. But not all fermentation environments are anoxic - while strictly speaking fermentation is anaerobic, there are plenty of oxygen loving (and oxygen tolerent) microbes that respire via other pathways, producing their own metabolic outcomes that get into the coffee, for better or for worse. Changing your fermentation environment, therefore, helps select for the desired microbial population that carries out your fermentation - this is why the same coffee split and processed different ways (dry ferments, wet ferments, sealed vessel ferments, etc etc) will taste different! And it's this "selecting for the population" that is crucial context before we get into the nuts and bolts of carbonic maceration.

A natural processed using carbonic maceration, and one put through a "classic" anoxic fermentation both use whole cherry in a sealed vessel; the difference is the introduction of carbon dioxide at the outset.

Any sealed fermentation vessel will reaches an anoxic state through respiration alone (and indeed, a submerged open tank fermentation will also reach anoxic conditions in the water), but this takes hours, during which obligate and facultative aerobes (microbes that either require or tolerate oxygen and may make use of it) remain active - and continue to remain active in an aerobic/open tank ferment, and oxidative enzymes in damaged tissue continue to function. Once the CO₂ from the fermentation reaches saturation point and all the oxygen is displaced, we could start calling anoxic fermentations "semi-carbonic" and it would technically be correct.

So what - then - is a carbonic maceration in this context? It's all about that initial purge - instantly flushing the tank as soon as the ripe, fresh cherries are added. High CO₂ concentrations select for lactic acid bacteria and certain yeasts while suppressing moulds and acetic acid bacteria, both in removing the oxygen but also dissolving into the water (if it is a wet ferment, or into the mosto) and rapidly acidifying it by forming carbonic acid. The fruit is saturated with carbon dioxide while still intact and metabolically active, rather than after microbial fermentation has begun.

The cherry pulp & mucilage arrives in the tank alive, holding free sugars and carrying the enzymes for fermentation already in place in its own cells - unable to respire, the cells route their metabolism through fermentation instead, and the fruit begins fermenting itself from within, consuming its own malic acid and producing ethanol inside intact cells until that ethanol breaks the membranes containing it and the tissue dies. This is the mechanism carbonic maceration takes its name from, and in wine and other fruits interesting aromatic molecules and precursors are created from this very step, and as the pulp macerates, it helps liberate these to diffuse into the coffee seed.

Ultimately, the difference in a carbonic macerated coffee - from an anoxic - is that initial purge, the rapid removal of aerobic microbes from the microbial succession and the tilting of the fermentation environment acid. A certain amount of pressure and intracellular fermentation will help macerate the fruit, but after enough time the conditions inside the barrels are basically the same! But in our experience, it absolutely can. Less acetic/vinegary funk notes, but often boozier - more alcoholic, reminding us often of high ester rums or fruit liqueurs. Often it's not the most elegant of processes but if you want a loud, shouty cup - there's few techniques out there that can match it for volume.

Bette Buna:

The first Bette Buna (“House of Coffee”) farm was founded in 2019, after Dawit inherited his grandfather’s coffee farm in Sidama. Dawit’s grandfather was a respected community leader, and with that in mind Hester and Dawit set out to create a sustainable, community led future for coffee farming in Ethiopia. They intend to achieve this by producing higher quality coffees, with collaboration and community development intimately linked to this. The funds from fair pricing and export help pay for community education and increased living standards, with living incomes a pillar of the Bette Buna mission.

Dawit and Hester have been purchasing the farms immediately abutting the Taferi Kela farm, adopting a high standard for purchasing (a minimum price for the land, alongside paying out 2 years of future production profits for the land at the point of sale), alongside offering the farmers employment at Taferi Kela.

By acting as a vertically integrated supply chain and increasing the export value of the centrally processed coffees, this both increases the income of the farmers turned employees beyond what selling their cherry to a station might have done, and socialises the profits whilst removing personal risk. Bette Buna have also established a nursery at Taferi Kela, distributing both improved JARC cultivars (higher yielding and more disease resistant) as well as shade trees and staple food crops, providing stable and consistent year round employment to the local community.

The impact of this nursery in terms of livelihood for subsistence farming cannot be understated, and the return to agro-forestry by increased shade tree planting is a positive move on a warming planet, and the distribution is directly tied to agronomic training workshops that help further increase yield and quality (and income) to boot. The work to establish more shade trees is hand-in-hand with a rewilding project to increase the native forest cover in the immediate area around Taferi Kela, and we expect to see this region increasingly start to get prestige off the back of their work.

Dawit and Hester’s second farm (the farm this lot hails from) is located in Guji, a region that has become famed for the particular quality of the natural process coffees produced here. Coffees from Guji are deeply fruity and berrylike, something we particularly enjoyed as a contrast when compared to the tarter citrus and white flower cups that you might find in Yirgacheffe or Sidama coffees.

The provenance of Ethiopian coffee regions is really not unlike that of the different wine regions in France - particular combinations of altitude, microclimate and the local predominance of local landraces vs locally improved cultivar plantings (akin in effect to the different varieties of grapes you might find in the wine regions) shift the cup profile. Fruit flavours are a real highlight of Ethiopian coffee - from the lower grade lots that intermingle with chocolate and spice notes, to the highest grades that are so outrageously sweet, bright and floral that prior to high technical intervention coffee used to be the main gateway into discovering speciality coffee. We think that Ethiopia is such an under-valued origin - the same cup profile from a high altitude farm in Central or South America would command a hefty premium.

The Megadu farm in Guji is over 220 HA, lead by 3 community leaders (Abbaa Gadaa). Of this 220 HA, Bette Buna manages a quarter, acting as a pilot project for many of the community lead initiatives Hester and Dawit run. The processing station, located centrally in the farm, allows high value return processing (such as anoxic fermentation and extended ferments) alongside well executed classic processing, and crucially drying. Both farms produce their own coffee for production, but also purchase cherry from local smallholders for onwards processing.