The James Hoffmann Fermentation Project 2026 is a worldwide coffee tasting experiment exploring one deceptively simple question:
What does fermentation actually change in the taste of coffee?
Created by James Hoffmann and coffee fermentation specialist Lucia Solis, in collaboration with Caravela Coffee, the project takes one coffee from Guatemala and processes it in four different ways.
The same coffee. The same farm. The same harvest.
But four different approaches to fermentation and processing.
One coffee acts as a control with no intentional fermentation. Another undergoes wild fermentation using naturally occurring microorganisms. The remaining two are inoculated with selected bacteria and yeast.
Coffee drinkers around the world will taste all four side-by-side during a global guided cupping on Saturday 3rd October 2026.
Ómra is one of the participating roasters, and we'll be documenting the project from green coffee through roasting and eventually into the cup.
What Is the James Hoffmann Fermentation Project?
The Fermentation Project is a global comparative coffee tasting created by James Hoffmann and Lucia Solis.
Instead of simply presenting four different fermented coffees, the experiment starts with the same coffee and deliberately changes the way it is processed.
That distinction is important.
Normally, if we compare a traditionally washed coffee with an experimentally fermented coffee, we're probably changing far more than fermentation.
The coffees might come from different countries.
Different farms.
Different varieties.
Different altitudes.
Different harvests.
They may even have been roasted completely differently.
That makes it incredibly difficult to isolate what fermentation actually contributed to the flavour.
The Fermentation Project takes a different approach.
By dividing the same coffee into four processing treatments, it gives us something much closer to a controlled comparison.
What Is the Purpose of the Fermentation Project?
The purpose isn't simply to discover which fermentation method creates the "best" coffee.
It's to understand what changes.
When people taste fermented coffees, they rarely get the opportunity to taste the same coffee without that fermentation.
The Fermentation Project gives us a control coffee alongside three different microbial treatments.
That allows us to explore questions such as:
- What changes when fermentation is introduced?
- How does wild fermentation compare with a selected microbial culture?
- Does bacterial fermentation taste noticeably different from yeast fermentation?
- Do acidity, sweetness, aroma or texture change?
- Are the differences as dramatic as we expect?
- And ultimately, which coffee do we actually prefer?
Rather than being told what fermentation does, we get to taste the experiment ourselves.
Where Does the Fermentation Project Coffee Come From?
All four coffees originate from Finca San Miguel Urias in Antigua, Guatemala.
The farm is owned by Hector and Lilian Leal and operated under Rueda Farms.
It is situated in Guatemala's Antigua Valley between Ciudad Vieja and San Miguel Dueñas, within one of the country's best-known coffee-growing regions.
The lot used for the project is composed predominantly of Caturra, alongside H1 and a small amount of Bourbon.
After harvesting, the coffee was divided so that different processing protocols could be applied while maintaining the same underlying coffee as the starting point.
This is what makes the comparison possible.
What Are the Four Coffees in the Fermentation Project?
The Fermentation Project contains four versions of the same Guatemalan coffee.
1. Mechanically Demucilaged Coffee (The Control)
The first coffee underwent no intentional fermentation.
Instead, the mucilage surrounding the coffee seed was mechanically removed.
This coffee acts as the control for the experiment.
Its inclusion means we're not simply comparing three different fermentations against one another. We also have a reference point for the underlying coffee when microbial fermentation is largely removed from the processing equation.
2. Wild Fermentation
The second coffee underwent a 48-hour wild fermentation using the microorganisms naturally present on the coffee and within its processing environment.
No selected starter culture was introduced.
This gives us a comparison with a more traditional approach in which the naturally occurring microbial population drives the fermentation.
3. Lactobacillus-Inoculated Fermentation
The third coffee underwent a 48-hour fermentation inoculated with Lactobacillus.
Lactobacillus is a group of lactic acid bacteria capable of producing organic acids during fermentation.
Introducing a selected bacterial culture allows the project to explore how a bacteria-dominated fermentation differs from both the wild fermentation and the non-fermented control.
4. Saccharomyces Yeast-Inoculated Fermentation
The final coffee underwent a 48-hour fermentation inoculated with Saccharomyces yeast.
Yeasts play a major role in many fermented foods and drinks and also occur naturally within coffee fermentation environments.
Here, however, a selected yeast is deliberately introduced.
This allows us to compare a yeast-guided fermentation directly against the bacterial, wild and control coffees.
Why Is There a Coffee With No Fermentation?
The mechanically demucilaged coffee may actually be the most important coffee in the entire experiment.
It's the control.
Imagine tasting the wild, Lactobacillus and yeast coffees without it.
We could identify differences between those three cups, but we still wouldn't know how much they had changed relative to the underlying coffee.
The control gives us a baseline.
That means we can ask:
What does the coffee taste like without an intentional fermentation stage?
Then:
What changes when we introduce one?
And finally:
What changes when we deliberately influence which microorganisms participate?
That's what turns four bags of coffee into an experiment.
What Is Coffee Fermentation?
Fermentation is not a new invention in specialty coffee.
Microbial fermentation has been involved in coffee processing for generations, particularly as a practical way of helping remove the sticky mucilage surrounding coffee seeds after depulping.
What's changing is how deliberately producers can understand, monitor and control it.
Variables such as time, temperature, oxygen availability and microbial populations can increasingly be considered during processing, while selected yeasts or bacteria can also be introduced through inoculation.
We've written a separate guide exploring this in much more detail:
Want to understand fermentation in more detail? Read our complete guide to coffee fermentation, including how the process works, why coffee is fermented and how wild, yeast and bacterial fermentations differ.
Who Is Lucia Solis?
Lucia Solis is a coffee fermentation and processing specialist with a background in wine, microbiology and fermentation science.
She studied Viticulture and Enology at the University of California, Davis, specialising in microbiology and fermentation science, before spending nine years working in wine production in California's Napa Valley.
Her focus shifted towards coffee in 2014.
Since then, Lucia has worked directly with coffee producers to better understand and manage fermentation during post-harvest processing.
Her work is particularly relevant to this experiment because it treats fermentation as more than a way of creating unusual flavours.
Fermentation can also be about control, consistency, repeatability and reducing processing risk for producers.
For The Fermentation Project, Lucia worked with the production team to develop and oversee the different processing protocols used for the four coffees.
How Does the James Hoffmann Fermentation Project Tasting Work?
The four coffees are designed to be tasted together using cupping.
Coffee cupping is a standardised way of comparing coffees without introducing many of the variables associated with different brewing methods.
Each coffee is ground into a cup or bowl.
Hot water is poured directly over the grounds.
After steeping, the crust that forms at the surface is broken and the coffee is eventually tasted using a spoon.
Preparing all four coffees with the same dose, grind, water and steeping time makes differences between them easier to identify.
You don't need to be a professional coffee taster to participate.
In fact, we'd encourage you not to worry about identifying specific tasting notes.
Start with the obvious questions.
Does one smell different?
Which tastes sweeter?
Does the acidity change?
Does one feel heavier or lighter?
Which has the longest finish?
Which cup do you keep returning to?
And most importantly:
Which one do you prefer?
When Is the James Hoffmann Fermentation Project Tasting?
The worldwide guided tasting is scheduled for:
Saturday 3rd October 2026
The current expected start time is approximately 3:00pm UK and Ireland time.
Coffee drinkers around the world will prepare the same four coffees and taste them during an online guided session led by James Hoffmann.
Final participation details and timing will be shared with customers ahead of the event.
Do I Have to Join the Live Tasting?
No.
Although joining thousands of other coffee drinkers around the world is part of the fun, you can complete the experiment independently.
Our Ómra tasting set includes a comparative tasting booklet to help you record what you experience across the four coffees.
The guided session is also expected to remain available afterwards, on Youtube, meaning you don't necessarily need to be available at the live time.
How Much Coffee Do I Need for the Fermentation Project?
Our Ómra edition contains 100g of each of the four coffees, giving you 400g in total.
That means you'll receive:
- 100g Mechanically Demucilaged
- 100g Wild Fermentation
- 100g Lactobacillus-Inoculated
- 100g Saccharomyces Yeast-Inoculated
We chose 100g portions because we don't want this to be a single-use tasting experience.
There's enough coffee to take part in the comparative cupping and then return to the coffees afterwards.
You might cup them together first, then brew your favourite individually through a V60, AeroPress or another brewing method.
Sometimes the most interesting part of an experiment is going back afterwards.
Where can I buy The Fermentation Project in the UK and Ireland?e?
The Fermentation Project is being made available through participating coffee roasters around the world.
Ómra Coffee is a participating roaster based in Northern Ireland, serving customers throughout the UK and Ireland.
Our James Hoffmann Fermentation Project tasting set contains all four coffees in 4 × 100g portions, alongside our comparative tasting booklet.
Pre-order the Ómra James Hoffmann Fermentation Project Tasting Set →
Availability is limited to our allocation of the project coffees.
When Will Ómra's Fermentation Project Coffee Be Roasted and Shipped?
Our current schedule is:
Roast date: Monday 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.
Orders will be dispatched with enough time for delivery and for the coffees to rest before the tasting.
*Dates and times remain subject to change. Confirmed updates will be communicated to customers before dispatch.
What Are We Learning From Roasting the Fermentation Project Coffees?
The experiment doesn't begin for us when hot water hits the coffee.
It began when the green coffees arrived at the roastery.
We've already completed initial test roasts of all four processing treatments at Ómra and found something particularly interesting.
Despite their different fermentation treatments, all four coffees behaved remarkably similarly during roasting.
Using the same roasting approach, our initial batches reached almost exactly the same endpoint at almost exactly the same time.
We've also been measuring and comparing the green and roasted coffees and documenting physical differences between the four treatments.
That gives us another layer to the experiment:
How much does fermentation change the physical coffee and its behaviour during roasting and how does that ultimately translate into flavour?
We'll be publishing our roast data and observations separately as the project develops.
Follow the Fermentation Project With Ómra
The global tasting is ultimately one moment in a much bigger experiment.
Between now and October, we'll be exploring:
What coffee fermentation actually is.
Wild fermentation and naturally occurring microorganisms.
Lactobacillus and bacterial fermentation.
Yeast inoculation.
The mechanically demucilaged control.
How the four coffees behave during roasting.
How to cup coffee at home.
And eventually:
What we actually taste when all four coffees are placed side-by-side.
The Fermentation Project gives us something unusually valuable in coffee — an opportunity to change one major variable and experience the result ourselves.
One coffee.
One farm.
Four processing approaches.
A control.
Three fermentations.
And thousands of people around the world tasting the results together.
Pre-order the Ómra James Hoffmann Fermentation Project Tasting Set →