Fig, raisin, and complex baking spice aromatics introduce a cup with rich molasses-like sweetness, and flavors of cherry, plum, and black tea.
The traditional approach to “wet processing” in Burundi often includes an 8-10 hour “soak” of the coffee parchment in clean water prior to drying. With the support of our friends and partners at the Long Miles Coffee Project, Passenger was able to contract a small lot from the 2020 harvest on Gaharo hill and requested that half be processed with the soak, and half without. Having preserved these experimental lots in the freezer since their arrival, we are excited to share them at the present time: providing a limited opportunity to assess the impact of this processing variable through comparative tasting.
On Passenger’s most recent trip to Burundi, in February 2020, we asked our sourcing partners at the Long Miles Coffee Project if they would be willing to help us conduct two processing experiments. The general goal for the experiments was to explore two of the key phases of traditional wet processing at Long Miles: the fermentation stage, and the post-fermentation soak. Later in 2020, we released the first two experimental lots from this project - one of which was processed using “wet fermentation” and one of which was processed using “dry fermentation”. Two years later, we are very excited to add the two remaining experimental lots to the Education Lot menu, shifting the focus from the fermentation stage to the post-fermentation soak.
Here are the basic steps of the Long Miles team’s default approach to wet processing in Burundi:
- During the harvest season, handpicked coffee “cherries” are delivered to one of the Long Miles washing stations by local farmers.
- The cherries are checked/sorted for consistent ripeness and individual farmer deliveries are received, weighed, and recorded by the Long Miles team to ensure lot traceability and calculate farmer payment.
- Coffee cherries are then passed through a disc pulping machine to remove the fruit from the seeds.
- Freshly pulped coffee seeds are fermented in open air tanks filled with clean water (i.e. “wet fermentation”). The reason for the fermentation stage is to help remove the sticky, sugary layer of mucilage that remains on the surface of the coffee seed after the fruit has been removed by the pulping machine. Yeasts and bacteria in the air, on the fruit, and in the water play a key role in breaking down the sugars in the coffee’s mucilage.
- After 12-18 hours of wet fermentation, the coffee is washed in grading channels (removing defective seeds and sorting by density) at which point the mucilage has been completely cleaned away and a handful of formerly sticky coffee seeds feel smooth to the touch, like river pebbles.
- At this stage, the coffee undergoes a post-fermentation soak in clean water, usually for 8-10 hours.
- Following the soak, the beautifully processed coffee “parchment” is spread out on raised beds and carefully dried in the sun until the coffee reaches its target moisture content. Drying is usually completed in approximately 30 days.
The questions we wanted to explore with this particular experiment were: Does the post-fermentation soak (step 6) have a noticeable impact on how the coffee tastes in the cup? What if the soak stage was skipped and the coffee went to the drying beds straight from the washing channels?
This coffee was prepared according to the default approach that we outlined above, but with one important modification: the post-fermentation soak was skipped. Both this lot and the Gaharo (Soaked) experimental lot (that is also being added to the Education Lot menu at the time of writing) were processed from the same single allotment of cherry that was harvested on Gaharo hill and delivered to the washing station on June 9th, 2020. The only difference between the two is that one was processed with the post-fermentation soak and one was not.
So, having had the opportunity to taste these experimental lots side-by-side, what conclusions, if any, can we make about the impact of the soak on eventual cup profile? In support of those of you who wish to preserve objectivity for comparative tastings of your own, we will stop short of sharing our full thoughts on how the soaked and unsoaked lots compare in the cup. What we will share for now: (1) our team finds both of them to be very enjoyable, and (2) while clearly coffees from the same place, we found more of a discernible difference between the two than we expected!