In October 2026, coffee drinkers around the world will taste four versions of the same Guatemalan coffee side by side.
The Fermentation Project, created by James Hoffmann and coffee fermentation specialist Lucia Solis in partnership with Caravela Coffee, is designed to explore a deceptively simple question:
What does fermentation actually change in the taste of coffee?
One coffee from Finca San Miguel Urias in Antigua, Guatemala was divided and processed using four different protocols — including a mechanically demucilaged control with no intentional fermentation.
By keeping the major starting variables consistent, the project gives us a rare opportunity to compare the influence of fermentation directly.
Pre-order the Ómra Fermentation Project tasting set →
Why is the Fermentation Project experiment different?
Normally, comparing a washed coffee with an anaerobic or inoculated coffee also means comparing different farms, varieties, harvests or terroirs.
Here, the major starting variables are kept consistent and the processing protocol becomes the principal variable being explored.
Where does the Fermentation Project coffee come from?
The coffees were produced at Finca San Miguel Urias, owned by Hector and Lilian Leal and operated under Rueda Farms.
The farm is located in the Antigua Valley of Guatemala, between Ciudad Vieja and San Miguel Dueñas, within the recognised Antigua growing region.
What are the four coffees in the Fermentation Project?
1. Mechanically Demucilaged - The Control
No fermentation - the control coffee
The mucilage surrounding the seed was removed mechanically rather than through fermentation.
2. Wild Fermentation
48-hour submerged fermentation with naturally occurring microbes
This coffee underwent a submerged fermentation using the native microorganisms already present on the fruit and within the farm environment.
3. Lactobacillus-Inoculated Fermentation
48-hour submerged fermentation with selected bacteria
A selected Lactobacillus culture was introduced to guide the fermentation.
4. Saccharomyces Yeast-Inoculated Fermentation
48-hour submerged fermentation with selected yeast
The fourth coffee was inoculated with a selected Saccharomyces yeast culture.
The lot is composed of approximately:
- 85% Caturra
- 15% H1
- with a small amount of Bourbon
All four processing protocols were overseen by Lucia Solis, who worked closely with the farm team throughout pulping, fermentation, washing and drying.
Why was this coffee selected for the Fermentation Project?
For a project like this to work, the underlying coffee needs to be both consistent and expressive.
The goal was to choose a coffee capable of clearly showing the nuances created by different fermentation approaches while remaining clean, sweet and approachable in its own right.
That is important because The Fermentation Project is not about creating four deliberately extreme coffees.
Instead, the aim is to taste how the same coffee changes when fermentation is removed, allowed to occur naturally, or guided using selected microorganisms.
The four cups should still feel connected. What we are looking for are the differences that emerge between them.
What does fermentation do in coffee processing?
Fermentation is sometimes discussed in specialty coffee as though its sole purpose is to create unusual flavours.
In reality, it has traditionally served a much more practical purpose.
After a coffee cherry is pulped, a sticky layer called mucilage remains attached to the seed. During a traditional washed process, microorganisms break down this mucilage, making it easier to remove before the coffee is washed and dried.
At the same time, microbial activity can produce acids, alcohols and other compounds that influence the chemistry surrounding the coffee seed.
That means fermentation is both:
- a functional stage of coffee processing;
- and an opportunity for flavour development.
The Fermentation Project explores what happens when that stage is managed in different ways.
Why include a coffee with no fermentation in the Fermentation Project?
The mechanically demucilaged coffee is particularly important because it gives the experiment a control.
Its mucilage was physically removed without an intentional fermentation stage.
Without this coffee, we could compare wild fermentation with Lactobacillus and yeast fermentation, but we would not have a clear reference for what the coffee tastes like when fermentation is largely removed from the processing equation.
The control allows us to ask two different questions:
-
What changes when fermentation is introduced at all?
- What changes when the microorganisms responsible for that fermentation are deliberately selected?
That is what makes tasting the four coffees together so interesting.
Who is Lucia Solis?
Lucia Solis is a coffee fermentation and processing specialist with a background in viticulture, enology and microbiology.
Before working in coffee, she worked in wine production, where fermentation is treated as a carefully managed biological process rather than simply something that happens naturally.
She has since applied that experience to coffee processing, working directly with producers to develop fermentation protocols that are practical, repeatable and better understood.
For The Fermentation Project, Lucia worked closely with the team at Finca San Miguel Urias to oversee the processing of all four lots.
That means the differences between them were not simply created by leaving coffees in tanks for different lengths of time. Each process was deliberately designed and executed.
What is a coffee cupping?
The Fermentation Project will culminate in a worldwide comparative coffee cupping.
Cupping is a standardised way of tasting coffee. Rather than using a pour-over brewer, espresso machine or other brewing method, ground coffee is placed directly into a cup or bowl and hot water is poured over it.
After several minutes, the crust of coffee grounds that forms on the surface is broken and removed before the coffee is tasted with a spoon.
Because each coffee can be prepared using the same:
- dose;
- grind;
- water;
- temperature;
- and steeping time,
Cupping makes it particularly useful for comparing coffees side by side.
You do not need professional tasting experience to take part.
The objective is simply to notice what changes from one cup to another.
New to cupping? Read our step-by-step coffee cupping guide →
What should you look for during the Fermentation Project tasting?
You do not need to identify specific fruits or flavour notes.
Instead, begin with broader differences.
Ask yourself:
- Does one coffee smell more intense?
- Is one noticeably sweeter?
- Does the acidity feel different?
- Does the texture change?
- Is one coffee cleaner or heavier?
- Does one finish differently?
- Which cup do you naturally return to?
One of the reasons we will not publish tasting notes before the event is that we do not want to tell participants what they are supposed to find.
The experiment becomes much more interesting when you record your own impressions first.
When is The Fermentation Project global tasting?
The worldwide guided cupping is expected to take place on:
Saturday 3rd October 2026 at approximately 3:00pm UK and Ireland time.
Coffee drinkers around the world will prepare the four coffees and taste them together during an online session led by James Hoffmann.
Final timings and participation details remain subject to confirmation and will be shared with customers before the event.
Do I need to attend the live tasting?
No.
The coffees can be cupped independently using the accompanying Ómra tasting booklet, and the guided session is expected to remain available afterwards on Youtube.
That means you can still complete the experiment even if you cannot join live.
However, there is something particularly interesting about thousands of people around the world tasting the same four coffees at roughly the same time and comparing what they notice.
How much coffee is in the Ómra tasting set?
Our edition of The Fermentation Project contains:
- 100g Mechanically Demucilaged
- 100g Wild Fermentation
- 100g Lactobacillus-Inoculated Fermentation
- 100g Saccharomyces Yeast-Inoculated Fermentation
That is 400g of coffee in total.
We deliberately chose 100g portions rather than treating the project as a single-use sample set.
There is enough coffee to take part in the worldwide cupping, repeat the comparison afterwards and then brew each coffee individually to understand it outside the cupping table.
Each set also includes an Ómra comparative tasting booklet with information about the project and space to record your observations.
Where can I buy The Fermentation Project in the UK and Ireland?
Ómra Coffee is one of the participating roasters offering The Fermentation Project from Northern Ireland.
Our 4 × 100g Fermentation Project tasting set is available to pre-order now.
The coffees are expected to be roasted in September ahead of the worldwide tasting on 3rd October 2026.
4 × 100g coffees · 400g total · Ómra tasting booklet included
Pre-order The Fermentation Project tasting set →
Important dates
Roasted: Tuesday 14th September 2026*
Expected dispatch: During the week ending Sunday 20th September 2026*.
Worldwide guided cupping: Saturday 3rd October 2026, expected at 3:00 pm UK and Ireland time*
*Dates and times remain subject to change.
Take part in The Fermentation Project
The interesting question is not simply which of the four coffees tastes best.
It is whether you can identify what changes when fermentation is introduced, what changes when it occurs naturally, and what happens when particular microorganisms are deliberately selected.
One coffee.
Four processing approaches.
A control, three fermentations and a worldwide tasting designed to make the differences easier to understand.