coffee society journal — fermentation, part four
We wrote before about the water you brew with. This one is about the water a coffee meets months earlier, in the washing channel, the fermentation tank, and the rinse before drying. Its temperature sets the speed of fermentation, its cleanliness decides whether off-flavors sneak in, and in a lot of growing regions its scarcity decides which processes are even possible.
01water sets fermentation's thermostat
A fermentation tank is mostly water, and water holds its temperature stubbornly. Cool mountain water slows the microbes down and stretches fermentation into something long and controllable, while warm lowland water speeds everything up, which is how a tank can quietly overshoot in an afternoon. Producers who chill or shade their water are doing careful flavor work with the cheapest tool on the farm.
02clean in, clean out
Fermentation water touches every seed in the lot, so whatever lives in it joins in. Recycled tank water carries yesterday's microbes into today's batch, sometimes as a deliberate starter (a bit like a sourdough) and sometimes as a slow drift into fermented off-flavors nobody chose. The best washing stations treat their water like an ingredient. It's fresh for the final rinse, monitored in the tanks, and disposed of responsibly, since fermentation runoff can be hard on rivers.
03why some regions dry instead
Washed processing can take a serious amount of water per kilo of coffee. In dry regions, like much of Ethiopia's natural-process tradition and parts of Brazil, sun-drying whole cherries wasn't a style decision first, it was about the water that was available. The flavor identity followed the constraint.
04common questions
Traditional channels used a lot, but modern eco-pulpers use a small fraction of that. When we talk with producers, water handling is part of what we ask about, because it predicts quality and it matters on its own.
Not directly, but you can taste what it did. Overheated tanks tend to read as harsh ferment, and dirty recycled water reads as mustiness. Clean, cool water reads as clarity.
Not at all. Naturals dried carefully on raised beds are some of the most prized coffees anywhere. Different constraint, different beauty.
we ask about the tank, so you don't have to
Every lot we buy comes with its processing story, but it had to score 85+ blind before the story mattered. Come taste what careful water work does.
current lots the water you brew withcoffee society · specialty micro roaster · berkeley, ca · est. 2023