Field Notes · Processing Deep Dive

We don't usually lead with process. The coffee leads. But occasionally a lot arrives where the processing decision is interesting enough on its own terms, not as a curiosity but as a genuine reason the coffee tastes the way it does.

This Nicaragua from Sabio is one of those coffees. Villa Sarchi, anaerobic washed, grown across Jinotega and Matagalpa at 1,200 to 1,450 metres. What's in the cup: elderberry, black currant, orange zest, hazelnut, bright and well-defined, layered without being busy. The process isn't incidental to that. It's the reason.

What Anaerobic Washed Processing Is

Every coffee undergoes some form of fermentation, and the question is how much control the producer has over it and what they're actually trying to achieve.

In conventional washed processing, coffee is depulped, fermented briefly in open conditions, washed, and moved to drying. The fermentation window is typically 12 to 24 hours, taking place in open tanks where ambient microbes, temperature, and airflow all play a role. It loosens mucilage and nudges acidity, and then it's over.

Anaerobic washed processing changes the environment entirely. After depulping, the coffee is sealed into airtight tanks, and from that point oxygen is excluded. As fermentation begins, CO₂ builds up inside the tank and pressure increases, with gas escaping through one-way valves while nothing comes back in. The microbes working on the coffee are now operating under very different conditions than they would in an open ferment, which shifts which acids develop and how the sugars in the mucilage break down. Lactic acid fermentation becomes dominant, producing a cleaner, more structured complexity than acetic-forward open ferments tend to, and flavour compounds that would otherwise dissipate in an aerobic environment are retained. The sealed conditions also allow producers to monitor what's happening throughout, pH, brix, and temperature tracked against the clock rather than left to ambient conditions.

How Sabio Does It

At Sabio's farms in Jinotega and Matagalpa, cherries are floated after picking to remove defects, then depulped before entering the tanks, where they ferment sealed for 48 hours with pH, brix, and mass temperature monitored throughout. After fermentation, they're floated again, washed with clean water, and moved to patio drying for 12 days. The coffee then rests in parchment for 10 weeks before hulling, a stabilisation period that lets the profile settle before anything moves. Green coffee is stored in Ecotact bags through transit.

Sabio hulls late because coffee from an anaerobic ferment is still resolving in the weeks after processing, and the parchment stabilises moisture while the aromatic compounds settle into the seed. Coffee moved too early tends to taste like it, a rawness around the edges that the 10-week rest removes from the equation entirely.

Why Washed, Not Natural

Villa Sarchi is a natural dwarf mutation of Bourbon, first documented in Costa Rica in the 1950s, and it's a varietal that is already fruit-forward and precise by nature. The same genetic shift that causes the plant to grow compact and low-branching also produces a flavour clarity that holds its definition under careful processing, so the fruit character is already present in the seed without any help from the drying stage.

A natural process would push that fruit toward something heavier and more saturated, softening the brightness and burying the varietal's defining quality under the weight of the dried cherry. The anaerobic washed method keeps the seed at the centre instead, where the controlled fermentation adds complexity without the cherry dominating, and you get the structural interest that the anaerobic environment provides, the elderberry and currant and the aromatic layering, without the heaviness. The orange zest mid-palate stays clean. The hazelnut in the finish adds warmth without pulling the cup away from the brightness that defines the rest of it.

A different producer might have gone natural with this varietal and made something genuinely interesting, but they would have made a different coffee, one where the process is more visible than the seed.

Anaerobic Washed vs. Anaerobic Natural

Both approaches begin in sealed, oxygen-free tanks and both produce coffees with a particular kind of structural complexity that open ferments don't achieve in the same way. The difference is when the cherry comes off.

In anaerobic natural processing, the whole cherry enters the tank intact, the skin stays on throughout fermentation, and the coffee dries in fruit, often for weeks. Flavour pickup from the cherry is maximal, and the results can be remarkable, but the margin between vivid and overworked is narrow.

In anaerobic washed processing, the cherry is depulped before sealing, so the coffee isn't carrying the full weight of the fruit through the drying stage. What comes through is the structural benefit of the anaerobic environment without the cherry dominating the final character, a cup that's cleaner, more defined, and where the varietal has more room to show through.

How to Brew It

Filter, pourover or Aeropress. Brew slightly cooler than usual, around 90 to 92°C, and give it a minute to open up before the first sip. The elderberry and currant come forward first, lifted and precise. The orange zest develops through the mid-palate as the coffee cools slightly, clean and aromatic. The hazelnut arrives in the finish, adding warmth and weight without pulling the cup away from what makes it interesting.

Nicaragua · Villa Sarchi · Anaerobic Washed Jinotega & Matagalpa · 1,200–1,450 MASL · Filter Roast Tasting notes: Elderberry · Black currant · Orange zest · Hazelnut

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Field Notes is where we write about what's in the hoppers, what's interesting at origin, and the decisions — by producers, by us — that make the coffee taste the way it does.