REGION: Antigua Valley, Guatemala

FARM: Finca San Miguel Urias (Rueda Farms)

PRODUCERS: Hector and Lilian Leal

PROCESSING LEAD: Lucia Solis

PROCESSES: Mechanically Demucilaged, Wild Fermentation, Lactobacillus Inoculated, Yeast Inoculated

VARIETY: Caturra, H1, Bourbon

ELEVATION: 1460-1540 MASL

INCLUDES: Four 4oz bags, one of each process

TASTING NOTES: Clean, sweet, and approachable across the set. Four distinct expressions of one coffee, from crisp and true to the bean to creamy, complex, and fruit forward.

What does fermentation actually do to coffee? The Fermentation Project was built to let you taste the answer for yourself. Fermentation specialist Lucia Solis took one single lot of Guatemalan coffee and processed it four different ways, using four distinct fermentation techniques. Same farm, same harvest, same beans. Every difference you taste in these four cups comes down to one thing: how the coffee was fermented. We are honored to be roasting it and bringing the set to you.

The coffee comes from Finca San Miguel Urias, owned by Hector and Lilian Leal and operated under Rueda Farms, located between Ciudad Vieja and San Miguel Dueñas in the Antigua Valley. This is genuine Antigua, one of Guatemala’s most celebrated growing regions, and the lot is a classic mix of Caturra, H1, and Bourbon. It was chosen because it is clean, sweet, and approachable, exactly the kind of coffee that lets the nuance of each fermentation shine through.

Every lot in the set was processed on site by Lucia Solis, the fermentation consultant behind the project. Lucia studied viticulture and enology at UC Davis, specializing in microbiology and fermentation science, and spent nine years in Napa Valley wine production before turning to coffee in 2014. Since then she has worked alongside producers in more than 15 countries, applying microbiological principles to bring control and reproducibility to one of the most variable stages of coffee production. Here is what she did with this lot, and what each technique tends to bring to the cup:

Mechanically Demucilaged. The sticky mucilage is stripped off by machine right after pulping, minimizing fermentation. This is the baseline: the coffee with as little fermentation influence as possible. Expect the cleanest, most straightforward cup of the four, the truest picture of the bean itself. Taste this one first.

Wild Fermentation. The coffee ferments spontaneously, driven only by the yeasts and bacteria naturally present on the fruit. Nothing added. This is the traditional approach, and it tends to bring extra complexity and character to the cup, with a bit of beautiful unpredictability that only nature can provide.

Lactobacillus Inoculated. A specific lactic acid bacteria culture is added to steer the fermentation in a deliberate direction. Lactic fermentations are known for rounding out the cup, often adding a smooth, creamy body and a soft, yogurt-like sweetness.

Yeast Inoculated. A selected yeast strain drives a controlled, reproducible fermentation. Yeast fermentations tend to amplify the fruit, often producing the most vibrant, aromatic, and fruit forward cup, with remarkable clarity from the guided ferment.

Getting an experiment like this from a hillside in Antigua to your kitchen takes a serious origin partner. That partner is Caravela, which has worked in Guatemala since 2016, building long-term relationships with 23 coffee-growing communities through three buying stations and a year-round, on-the-ground team. For this project, Caravela handled green coffee processing expertise, quality assurance, and export logistics, moving all four lots consistently and traceably from the wet mill to roasters around the world, including us.

Your set includes four 4oz bags, one of each process, so you can brew them side by side and taste cause and effect in your own kitchen. And you will not be tasting alone: James Hoffmann is hosting a live global tasting of all four coffees on October 3 at 3 pm UK time (10 am Eastern), so grab your set, keep it sealed until then if you can stand it, and taste along with coffee people around the world.

Our part in all of this is the part we love most: the roasting. This is a pre-sale with limited quantities, and once it is gone, it is gone. The full set roasts here at Tinker on September 14 and ships immediately after, so it lands at your door at peak freshness with plenty of time before the tasting. We cannot wait to hear what you taste.