Dispatch
A Workshop Dispatch — Anaerobic Naturals
A morning at a small roastery an hour out of town, where the cupping table is full of coffees that smell like red fruit and old books. Notes from a form of processing that has stopped being a novelty and started being a craft.
By For Lovers of Coffee · October 13, 2026
The roastery is up a lane we would have missed in the dark. Two bay doors, a Loring in the back, and a cupping table that fits six people if two of them are willing to stand. We came up on a Friday to drink coffees that most of our regular customers would not pour at home, and to leave with a better answer to the question we had been avoiding.
Anaerobic naturals get written about with the same handful of adjectives — funky, winey, boozy, strawberry-forward — and in a way that suggests the coffees are a single category. They are not. The best of them are a form of fermentation craft that has quietly moved from experiment to practice over the last five years. The worst of them are still bad, in the specific way that bad anaerobics have always been bad: muddled, overfermented, drinking like the barrel room at the end of a long shift. The difference is at the farm and it is at the roaster, and this morning was about learning to taste the difference.
What we drank
Six coffees on the table, all current crop, all roasted inside the last ten days. The host had set them up as pairs on purpose.
A Colombia Pink Bourbon, 72-hour anaerobic natural. Red-apple skin, cola spice, a quiet black-tea finish. This is the coffee that converts people. The fermentation does not announce itself. It just lets the fruit sit a little longer in the cup than you expect it to.
A Colombia Castillo, same farm, 96-hour anaerobic. Louder. More overtly fruit-wine. A little hotter in the finish. We liked it. The person next to us did not. It is the kind of coffee that honestly belongs in a flight, not as the only pour of the morning.
A Costa Rican honey, double-fermentation. Pure clove and honeyed apple. Very clean. The cleanest coffee on the table by a wide margin. This was the one we would pour for someone sceptical of the whole category.
A Ethiopian natural, carbonic maceration. Blackberry jam and a dark, treacly sweetness. Big. We would brew it on a filter at a 1:17 and stop thinking about ratios for a day.
An Ecuador Typica Mejorado, 120-hour anaerobic. This was the coffee the host apologised for. He said he was still deciding how he felt about it. We tasted — rose, lychee, a slight whisper of over-ferment at the back — and understood. These coffees land on a knife’s edge and sometimes the knife wins.
A Panama Geisha, washed, as a control. Jasmine, bergamot, honeycomb. Beautiful. A reminder that nothing about anaerobic is a replacement for a great washed coffee; it is a different conversation.
What we learned
The craft is in the time. Shorter ferments — 48 to 72 hours — tend to taste like the farm, with the fermentation as a quiet amplifier. Longer ferments can taste like the barrel, which is interesting the first time and tiring by the fourth cup. The roasters we trust the most are the ones who ask the producer to go a little shorter than the fashion, and then develop the roast a little longer than they would for a washed, because the sugars want to sit.
The craft is also in the roast. These coffees run hot in the first crack and need a steady hand through development. Underdeveloped anaerobics taste raw and vinegary. Overdeveloped anaerobics taste like cocoa and nothing else; the fruit vanishes. The window is narrow and the people who hit it consistently are a small group.
How we are brewing them at home this month
For the shorter-ferment coffees, a V60 at the recipe we published a couple of weeks back works beautifully — the slower, slightly wetter approach lets the fruit sit without going sharp. For the longer ferments, we have been using an AeroPress inverted, 15 g in, 220 g out, 85°C, a two-minute steep. The lower temperature calms down the fermentation notes and lets the sweeter end of the coffee speak.
For espresso — and some of these coffees sing as espresso — a slightly longer ratio helps. 1:2.5 instead of 1:2. The extra water drags the sweetness forward and gives the coffee somewhere to put the fermentation.
Why we drove out
A coffee we poured at the table today will land in our pantry next week and we will spend a Saturday with it. We also, honestly, came to see what a good small roastery is doing right now. The answer, which was quietly reassuring, is: the same thing good small roasters have always done. Buy from people you know. Roast less than you want to. Pour a lot of cups. Trust the cupping table.
We are putting one of these on the bench for November. We will tell you which one when we are sure.