As the market for specialty coffee continues to grow, so does interest in new, innovative, and unique coffees. Some roasters and consumers around the world have developed a strong interest in coffee that’s been through novel processing, finding that some approaches add significant flavor potential and other sought-after traits. In response to this, many producers and processors are trialing varieties, processes, and combinations of the two, hoping to create desirably innovative coffees to fit this growing market segment. Many with the resources to experiment in this way are finding that they can successfully create marketable flavor profiles, differentiation, branding, and value through targeted fermentation and other post-harvest processing practices.
At the same time, it is also becoming understood that aspects of fermentation – like equipment and materials used, additives, modified atmosphere, timing, and monitoring of key variables – can also support long storage life and product consistency.
At Cafe Imports, we’ve noted a rise in questions about processing, many of which either center around deciphering terminology or what the growing hype about methodology in fermentation and processing means for producers/processors and the coffees they create.
While gaining velocity today, conversations around processing and fermentation have been developing for some time in the specialty coffee industry and some folks jumped into the fray early on. Lucia Solis joined in roughly six years ago when these conversations were fairly nascent. Since then, with her experimentation, podcast, and workshops, she has made herself and her background in viticulture and enology available to the specialty coffee industry for the entry and insights it provides.
To jump in further, we recently sent our Coffee Production Researcher and Educator, Dr. Taya Brown, to a fermentation camp hosted by Lucia and her husband, Nick. The course took place in Risaralda, Colombia, just weeks ago in September 2022.
Our goals for attending were to better understand how to define and discuss various aspects of fermentation. Essentially, we aimed to glean what we could about where the evolving conversation currently stands regarding terminology, definitions, and delineations in post-harvest processing and fermentation. We also wanted to consider where things might be headed due to the interest of both producers and consumers, successes and failures each are having, marketability for roasters, and potential improvements to profitability for producers.
Being a green coffee outfit, we are often responsible for collecting and sharing information with our customers about coffees and the contexts in which they’ve been produced. Conversely, we also share what we know about market interest in varieties, processes, etc., with producers. We take these roles very seriously and aim to be as accurate as possible in how we discuss all things coffee, with everyone we speak with. The fermentation course offered an opportunity to calibrate ourselves, which we in coffee know is important – in this case, with the goal of calibration on processing and fermentation terminology.
Specialty coffee is a constantly evolving industry, and one of the things many of us love about it is the regular influx of new things to explore. As Café Imports does so, we intend to share the knowledge we gain with both the producers/processors we purchase coffee from and with the folks who purchase green coffee through us. Because this course was held in Colombia, it was a way to put ourselves where fermentation and processing were the topics of focus for several days, and where experts, specialists, and practitioners could all be present for the discussion.
The course we took part in was the second Lucia and Nick held in Risaralda in 2022. The majority of the activities took place at a glamping site in a valley about 30 minutes from town. The site had a small restaurant, a fishable pond complete with baby ducks, lodging for large groups, and plenty of space for the small-scale processing facility that was the basis of much of the course’s activities.
The 15 attendees were a mix of producers, mill operators, scientists, green buyers, and coffee enthusiasts.
Some were there to witness coffee being processed in-person for the first time. Others intended to take the experience back to their farm and/or mill, hoping to support consistency, improved flavor profiles, and marketable differentiation in their coffees. Others were there in more exploratory roles, much like we were.
Arriving on a Monday and leaving on a Friday, days were split between physically processing coffee, presentations given by Lucia on the theory behind what was taking place during the processing, and open discussion. Evenings were spent around a campfire discussing all things coffee and bonding as a group of individuals from various aspects of the industry with the strong common interest of wanting to improve coffee and the conversation around it continually.
The group collectively took part in converting 450 kg of cherry into three distinct lots of washed coffees. The cherry was received from a local producer in the evening the day the group arrived. Once the cherry was floated and depulped, it was separated into three lots, each of which received a different additive to support varied approaches to mucilage breakdown. This resulted in three lots of well-sorted, partially dried parchment at the end of the week.
All coffees were floated as cherry and then again after being depulped. The group learned that, while floating is an effective defect removal tool at the macro level which we can see, it is also important to understand what is happening at the microbial level, which we can’t see. For example, when coffee cherry is submerged under water – what is happening to the yeast and bacteria that is present due to either being ambient in the environment or having been introduced through picking and/or transport?
Actually, it is helpful to consider the microbiome all along as processing takes place. It is, after all, microbes that break down the carbon chains in the pectins, starches, and sugars of the mucilage. They also create and modify the flavor precursors that lead to different sensory attributes. Unfortunately, microbes are too small for humans to see but what we can see is evidence of their activity. Useful detectors of microbial activity are variables like temperature, pH, soluble solids, bubbles, color, smell, taste, and feel. It’s especially useful to note differences in these over time. Each batch will start with its own pH, temperature, and soluble solid concentration – generating a baseline of these indicators at the start provides a measuring stick by which to compare changes throughout the process, helping to understand what’s occurring at these levels we can’t see. The changes (or lack thereof) then help make decisions like when to try and drive more activity due to low movement, when things are moving too fast or in an undesirable direction, and when to call a fermentation complete.
The group learned that floating cherry creates a more ideal environment for microbes to be added to, which also helps reach the highest possible impact with investment in microbial additives like yeast. Submerging cherry in water reduces the ambient yeast, fungus, and bacteria load. It also brings all individual cherries to the same temperature, internally and externally. All yeast and bacteria species function and replicate differently (or not at all) outside their favored temperature range, therefore bringing all cherry in the lot to the same temperature at the start of processing supports the homogenous presence and activity of microbes. Basically, when you’re floating for defect removal, you’re also homogenizing the batch in several ways, which results in more consistency within batches and also between them. Because of all this, floating may result in greater consistency in general and a higher return on investment for microbial additives where those are used.
Success of yeast fermentation is substantially impacted by temperature, which is in turn impacted by the volume of coffee being fermented. For these reasons, the vast majority of the coffee used in the course – 190 kg of depulped sticky parchment – was put into a yeast fermentation. The two other processes were a lactic acid bacteria (LAB) fermentation and a citric acid mucilage breakdown, both done on a much smaller scale of just 8 kg each.
Yeast: The yeast started as a dry powder from a package and was brought to life by soaking in warm water for 20 minutes, then added to a large plastic tub of depulped coffee. A few gallons of water were added to the tank so the lot could be easily stirred and the yeast well incorporated. The amount of yeast used was based on the amount of depulped coffee only, and not based on the added water.
Lactic Acid: Both yeast and bacteria have the ability to break the carbon chains that make up the pectins, starches, and sugars, and both can “ferment” food products. The lactic acid bacteria (LAB) fermentation was facilitated by adding a 2% salt solution to the depulped parchment. According to Lucia, salt (NaCl) inhibits most microbial development but (usefully to us) does not inhibit all LAB species. By adding salt, the LAB naturally present in the mucilage (along with every other naturally present microbe) is preferentially selected for, outcompeting the others and becoming the majority of what degrades the pectins and sugars of the mucilage.
Citric Acid: For the citric acid process (CAP), high-acid fruit juice was added to the coffee, though concentrated citric acid could also be used and has less potential to impart flavor. Biological agents (microbes) use enzymes and other proteins to break up carbon chains and lattices. Acid does it differently – by ionization that breaks bonds between the molecules making up the carbon chains and lattices. It’s a chemical breakdown, not a biological one, and not considered a fermentation – it’s simply a degradation of the mucilage. Citric acid is strong enough to break down coffee mucilage and, depending on the ratio of acid to mucilage, can sufficiently complete the process in just a few hours.
While time is a factor in all things, the group learned that there are better indicators for understanding how much of the processing has been completed or still needs to continue, and its health as it progresses. Variables were measured and recorded multiple times a day for each process, including pH, soluble solids, and temperature of the coffee, as well as humidity and temperature of the ambient environment. These, along with observations like smell, color, feel, taste, and presence of bubbles, help to monitor progress and make targeted decisions.
The September attendees cupped the same three processes created a couple of months prior by the previous group. They were clean, balanced coffees with differing flavor profiles but all in the same profile realm – certainly marketable. It’s clear that the different processing methods did impact flavor in this case. The group was unable, of course, to see other potential benefits played out, like consistency between batches and/or longevity in storage.
Based on what was taught in the course, there are clear potential benefits to better understanding and, therefore, better manipulating processing. It makes sense that managing microbial activity (or any other means of mucilage breakdown) and evidence-based decision-making, provide an ability to target specific outcomes.
For example, measuring variables like pH and temperature help to know what is occurring at the microbial level, and have substantial utility over simply using time to call a batch “done.”
How to know what to target exactly, on the other hand, still feels a bit elusive. Whether or not each method produces the ideal profile for that coffee is a matter of experimentation and requires cupping. If a producer/processor can find a process that pairs well in their environment and with the varieties and resources they have, that’s a win. However, the experimentation must take place with targeted awareness and the results must be cupped. Cupping should occur many times and for all trials, as the benefits of methods like floating and adding microbes may truly live in the consistency and longevity of the coffees produced.
Field management in a changing climate, investment in an insecure economy, and innovation in the context of low resources and minimal security are all difficult for anyone. Coffee producers manage all of these risks simultaneously. At the same time, the market demands very specific results in the form of flavor profiles, consistency both across and between seasons, and longevity in storage. These are the traits everyone hopes for but only some have the ability to achieve.
One of the best things coffee roasters and consumers can do as they develop interest in innovative coffees is to become familiar with the effort and variables involved in production and processing. A general but accurate understanding of, for example, the impacts of changing rain patterns on production and processing, are very helpful in setting expectations for one’s own business, and in being a support to producers.
Innovations in processing are exciting and stand to push the envelope of what is possible to do with coffee. And, it takes a roaster to bring these innovations into the shop and find the right roast profile to combine along with all the other variables. This action completes the mission – decisions about variety, field management, harvest, and post-harvest processing culminate as each batch is dropped hot from the drum.
While this course was open about the fact that vocabulary around fermentation and processing isn’t well defined across the industry, and we didn’t come home with the encyclopedia of how to define crazy fermentations we had in mind (likely a bit too optimistically), it did provide the basis for understanding other aspects often not so clear. In a way, referring to homogenization, baselines, and monitoring targeted variables does provide a more accurate way to discuss processing – it provides the foundation to make fair comparisons between experiments, know when to expect varied results, modify what we don’t love, and replicate what works.
Stay tuned for more about processing and fermentation; our journey into terminology and better representation of the innovation taking place in this realm, along with its results, has not ended here.
Written by Dr. Taya Brown
Edited by Sam Miller