Co‑fermentation is gaining ground across an increasing number of producing countries, driven by shifting consumer tastes in a changing market
MILAN – Originating in the wine industry, co-fermentation – that is, processing technique where two or more distinct ingredients are fermented together at the same time – made its way into the coffee sector towards the end of the last decade, thanks to experiments carried out by a number of Colombian producers.
In classic methods, yeasts and bacteria break down the sugars in the cherry. In co-fermentation process, additional inputs enter the fermentation tank – such as fruits, herbs, spices or selected yeasts. The goal is to use these additional components to develop new, often unusual flavours in the coffee.
However, just as – and perhaps even more so than – simple fermentation, co‑fermentation is a divisive subject, and one that raises doubts not only about the flavour profile in the cup (“de gustibus”, as some would argue) but also about hygiene and safety.
Not to mention the methodological difficulties tasters face in conducting sensory evaluations of co-fermented coffees and assigning them a score.
“There are many approaches to co-fermentation,” the article states, “and there seems to be no single rule book.”
To continue the parallel with the world of wine, co-fermentation is also an expression of the terroir – that unique combination of environmental and human factors that link a product to its territory of origin, making it impossible to replicate elsewhere.
Each producer works and experiments by varying a range of parameters, which depend on the local climate or microclimate, the cultivar, the time of year and the co-fermentation agents available.
The latter may also include produce or agricultural by-products from the farm itself: lemongrass, mandarin peel or juice, raw sugar, pineapple pulp.
In some cases, the secret lies in the timing: too long an exposure risks causing the fruit to rot; too short a time may fail to produce the desired effect.
As already mentioned, there are many schools of thought and approaches to co-fermentation: some begin by working with yeasts and bacterial strains, moving on only later to experimentation with coffee.
Others do exactly the opposite, allowing the coffee cherry to ferment on its own before adding any kind of external agent. Finally, there are those who do not even refer to it as co-fermentation, but rather as “modulation”.
Although they operate independently with a wide variety of recipes and methods, many farmers and processers in Colombia share knowledge and results.
But co-fermentation is now gaining ground even outside Colombia
The aim is also to impart bolder, more distinctive flavour profiles to the coffee, able to meet evolving tastes, particularly in emerging markets such as Asia.
The article cites experiences in Vietnam, where fermentation was carried out using lavender to produce a coffee with strong floral notes. Or in Ethiopia’s Guji zone, where a 72-hour anaerobic natural pineapple co-ferment from Benti Nenka recently cupped 87 points.
According to Franciska Apró – from Sucafina’s quality control team – the first criterion is that the coffee must taste of coffee: “It’s all good if you can still recognize that you’re drinking coffee,” she said. The quality of the base coffee clearly matters too: if it possesses a distinct organoleptic profile, it will complement the notes added by co-fermentation without being overwhelmed by them.
The fact remains that scoring co-fermented coffees is still a challenge, one that not even the SCA’s new CVA (Coffee Valuation Scale) manages to resolve completely. Although, as Apró herself explains, even judging panels have started using co-fermented coffees specifically in competition calibrations, helping judges separate flavour that comes from the coffee itself from flavour that was added to it.
Finally, there is the issue of transparency regarding co-fermentation methods. Buyers demand the utmost clarity on how a batch is produced, not only for commercial reasons but also for consumer safety – for example, a consumer might be allergic to one of the ingredients used in the co-fermentation process.
Sebastián Romero, Sucafina’s Specialty Sourcing Coordinator in Colombia, points also to a related gap on the regulatory side. “Traditional cupping protocols were built to evaluate a coffee’s intrinsic qualities: everything that comes from terroir and processing, without anything introduced along the way. Co-fermented coffee doesn’t fit neatly into that framework and for Sebastián, developing a fair, standardized way to evaluate it is one of the next challenges,” he concludes.
