One coffee, four processes: a tasting experience for anyone who wants to understand more about what happens between harvesting coffee cherries and the brewing stage, and to taste what impact fermentation has on a coffee.

The Fermentation Project is a global coffee experiment created by James Hoffmann and fermentation specialist Lucia Solis, designed to explore one deceptively simple question: how much does fermentation actually change the flavour of coffee?

Starting with the same coffee from Finca San Miguel Urias in Antigua, Guatemala, the harvest was divided into four lots and processed in four different ways. By keeping the coffee itself consistent and changing the fermentation, the influence of processing becomes more evident than usual. 

In January this year, we visited some of our suppliers in Guatemala to connect and take a final look at the 2026 harvest of one of our key coffees – El Colegio. While visiting with Javier from Caribbean Goods, we had the opportunity to meet the team behind Finca San Miguel Urias, and see first-hand where the coffee for The Fermentation Project was grown, processed, and evaluated.

Inside the project are four versions of the same coffee:

• Mechanically Demucilaged – this is the control, with the mucilage mechanically removed and no intentional fermentation.

• Wild Fermentation – 48 hour fermentation using the microorganisms naturally present at the farm.

• Lactobacillus Fermentation – 48 hour fermentation, inoculated with lactobacillus bacteria.

• Yeast Fermentation – 48 hour fermentation, inoculated with saccharomyces yeast.

We'll be roasting all four lots here at Thomson's in September 2026, and you can experience the experiment for yourself – brewing them side by side, cupping them, or getting involved with the Global Tasting Event hosted by James Hoffmann on the 3rd of October.

Rather than telling you what you should be tasting, you can discover and interpret them for yourself, with no preconceptions!

This is a pre-order item – the packs will be shipping towards the end of September 2026.