Mossto (from mosto, Spanish for freshly pressed fruit juice) refers to the liquid produced during coffee fermentation – rich in sugars, organic acids, and active microorganisms. Instead of discarding it, producers reintroduce it into a new fermentation batch as a starter culture, turning wild fermentation into a controlled, repeatable process.
Origins
Inspired by winemaking’s reuse of must and yeast cultures, mossto processing was pioneered by farms in Colombia and Costa Rica that were already experimenting with anaerobic fermentation. The goal: replicate successful flavor profiles consistently, shifting processing from reactive to intentional.
How it works
As coffee cherries ferment, liquid accumulates in the tank. Producers collect this mossto – carrying active yeast, bacteria, residual sugars, and acids — and add it to the next batch. Like a sourdough starter, it accelerates fermentation and shapes flavour development.
In the cup
Mossto coffees tend toward pronounced sweetness, structured acidity, and layered complexity — riper fruit, deeper florals, wine-like texture, longer finishes. Done well, it’s clean and expressive. Overdone, it becomes heavy and overwhelming.
Why producers use it
Fermentation is difficult to control; mossto gives producers a reliable foundation rather than starting from scratch each time. It also creates differentiation — a distinct, repeatable signature in a crowded market.
Brewing tips
These coffees extract easily. If the cup tastes too intense, grind coarser, lower water temperature, or shorten brew time. If flat, push extraction slightly further.
The bigger picture
Mossto processing reflects how seriously producers now treat fermentation as a craft variable — as influential as origin or varietal. A good mossto coffee doesn’t just taste different. It tastes deliberate.