Why the topic "Coffee and Fermentation"?
When we think of innovations in specialty coffee, we usually think of advances in machines, grinders, scales, and roasters. Things that are supposed to help us make better coffee. But fermentation?
Lucia Solis – a leading expert on coffee fermentation (here's an einführendes interview with her) – therefore asks:
what if it's not machines, but microorganisms, living machines, that can make our coffee better?
Lucia is thinking about yeasts, microbes, and sugar. For thousands of years, humanity has used yeast populations to make bread, beer, wine, and so on. So why do we apply this knowledge so sparingly or not at all to coffee?
But before we can answer this question, let's explore the topic of fermentation in detail from the beginning. What it is, what it isn't, and what's possible with it.
You often hear from roasters or baristas that the coffee seed was "picked, pulped, fermented, and dried." Does it have to be this way? No. Coffee doesn't always have to be fermented. Often it's not just about flavor, but also about technical and financial feasibility.
We've divided this article into five chapters:
1. Fermentation and Coffee
2. Microbe-Climate instead of Micro-Climate
3. Fermentation as a Flavor Enhancer
4. Fermentation with Starter Cultures
5. Coffee Makers Go Science – Research Project on Santa Rita
1. Fermentation and Coffee
For several years, I've been judging barista competitions. I often heard competitors mention during their 15-minute presentations that the coffee was "pulped, fermented, and then dried."
The first and last are mechanical processes, which I've seen and understood during previous visits to coffee farms. But the middle part, the "fermenting" of the coffee, has never been entirely clear to me. There were so many questions, so many inconsistencies, and so many opinions about it.
I wanted to learn more about this important topic and immersed myself in these matters. I read what relevant coffee literature has to offer. But many of the commonly available information was similar to each other, and the added value seemed limited.
To understand the scientific, precise information, I needed some time. But once all the scientific terms settle, a new world opens up. Two events came along that made the whole topic suddenly much clearer to me:
- I came into contact with the highly current and compelling work of Lucia Solis
- we ourselves became scientifically active – in collaboration with the ZHaW, we conducted a research study on our Santa Rita Farm in Nicaragua (internal link)
What is coffee fermentation?
It's not necessarily clear that coffee can be fermented. And if it can, there's disagreement about what fermentation in coffee actually is.
When we talk about coffee, we often think of the bean and not the coffee cherry. For this and other posts, however, we want to think of coffee as a cherry: the combination of two seeds, wrapped in a hard shell, a mucilage layer, and skin. Botanically speaking: endocarp, mesocarp and exocarp.
In the coffee world, fermentation is often understood as a mechanical step to separate the pulp along with the slime (English mucilage or honey, Spanish baba or mucilago) from the seed. One of the most common definitions, especially among producers, goes like this:
The coffee is "finished" fermenting when the slime separates from the pulped coffee seeds in the fermentation tank; when the seeds in the fermentation tank crunch rather than stick together when stirred.
imprecise definition
However, this is not a clear definition, but rather a highly subjective perception of an inconsistent process that is influenced by countless conditions. So for this mechanical step, let's use the term demucilagination (Span.: desmucilaginación), the process of removing slime from the seed. "Mucilage removal" might be the appropriate word in English, but it doesn't sound quite as nice as the Spanish tongue-twister desmucilaginación.
Just because coffee is "demucilaged" or has the slime removed doesn't mean it has been fermented. Fermentation has been defined by scientists as metabolism, i.e., a biological process.
If we only consider fermentation as a mechanical process, we might avoid the assumption that the metabolism of microbes can produce desirable flavors in the seed.
What is fermentation?
Fermentation refers to the microbial or enzymatic transformation of organic substances into Säure, Gase or Alkohol. In this metabolism, yeasts and bacteria (microorganisms) convert sugars into energy and aromatic compounds.
Definition of Fermentation
In nature, microorganisms are already naturally present on the starting materials and come into play in spontaneous fermentation, for example. Fermentation then takes place with the help of these wild yeasts. The production of natural wine or sourdough bread serves as an example here.
In industrial fermentation, pure culture yeasts are used to better control fermentation and exclude unwanted byproducts.
Fermentation – from Risk to Possibility to Guarantee?
Let's stay a bit with the literature review: When Wrigley (1988), Wintgens (2012), and the FAO (2008) talk about fermentation in coffee, it's usually about avoiding risk. The longer the cherry isn't pulped, the greater the danger of a defect.
Quick pulping of the coffee cherry could therefore contain the risk of a flavor defect. This means in reverse: extended fermentation apparently offers no opportunity to refine the aroma, but rather presents a fundamental risk.
We must consider that these authors wrote standard works and gave general recommendations for the broad industry. As more and more coffee had to be produced and processed in the 1980s and especially in the 1990s, guidelines were created that defined coffee quality from the cup backwards to the origin.
From the perspective of specialty coffee, these recommendations often seem imprecise – but let's not forget: specialty coffee is a much younger phenomenon, and many of the things done today work on a small scale, but rarely on a large scale.
But what if we consider fermentation as a tool to make coffee taste even better?
Or, if we could use targeted fermentation to give lower-quality coffee more value? The goal should be to control fermentation precisely and not accept it as an unknown quantity. This would suddenly transform the "fermentation risk factor" into the "fermentation possibility."
Fermentation as a Tool
This opens up new possibilities for producers: once the fermentation process is carefully analyzed and understood, they can apply this knowledge to bring more consistency to coffee quality. Defects should become less common and new flavor profiles become the norm.
What we should remember up to this point:
- Coffee can, but doesn't have to, be fermented
- often the processes of "mucilage removal" and fermentation are mistakenly used as synonyms
- We distinguish here between mechanical removal of the mucilage (demucilagination) and biological removal by yeasts and bacteria
- fermentation is often seen as a risk – in cuppings, one often speaks of "ferment" as a defect – many cuppers still refer to coffees that are somewhat fruitier as ferment – but they fail to acknowledge a new reality: specialty coffees are becoming increasingly fruit-forward
- when coffee ferments, it usually does so through natural, wild yeasts that are already settled on the fruit and present in the air
- Since fermentation has long been viewed more as a mechanical process than as an aroma-defining process, there is still a lack of diverse research results today
Coffee seeds are squeezed from the cherry on a despulpadora2. Microbe-Climate instead of Micro-Climate
To show flavor differences in coffees, we also usually taste coffees from very different regions. The differences are best found when the coffees are placed side by side. This shows us regional differences in particular, but explains less the role that processing methods can play in flavor development.
Most differences between coffees are usually explained by variety, climate, and prevailing local conditions. But we probably overlook the contribution of microbes (yeasts and bacteria) which can have a significant influence on flavor development during the pulping process.
So let's ask ourselves: exactly how does coffee fermentation work?
We now know that during coffee fermentation, the sugars and starches of the mucilage, the slime layer surrounding the seed, are broken down by yeasts and bacteria (microorganisms) and converted into acids or alcohol.
This process always requires both actors: yeast and bacteria, since the latter act with the yeast, form enzymes, and begin to degrade the sugars in the mucilage.
We're mainly dealing here with lactic acid bacteria, which are particularly active in mucilage fermentation. Fats, proteins, and acids are also degraded and converted into alcohol acids. The smell, color, pH value, and composition of the mucilage change.
An Unstable Yeast-Bacteria Cocktail
The ratio of yeast to bacteria in the yeast-bacteria cocktail is never stable. Even within the same plantation, there can be significant differences in yeast-bacteria balance.
For example, if part of the plantation is closer to a cow barn, then completely different microorganisms are swirling in the air than if the plantation is directly next to a stream. Also, riper cherries harbor more bacteria and more yeasts on their surface.
More ripeness = more sugar = more yeasts and bacteria = more potential fermentation
The microorganisms are located on and in the fruit and increase with the ripeness stage. They become active immediately after harvest (or through cherry damage) and the first signs of unintended fermentation can occur now if, for example, the ambient temperature is high, the cherries are not of uniform quality, or they are stored in a location with many bacteria.
Temporary storage of ripe cherries in dirty baskets, buckets, pickup truck beds, fermentation tanks, etc. always means a change in the microbial climate. Every contact with air, surfaces, or skin (essentially always), changes the balance of the yeast-microbe cocktail.
A reality – fermentation tanks are often not clean and not covered. Uncontrolled fermentation can quickly occur here.
If the goal is for coffee fermentation to always proceed completely uniformly, then it's not enough to only look at all processes from the pulper onward, but also from the bush to the pulper.
In Brief
- The fermenting organisms use the pulp as an energy source (carbon and nitrogen) and produce high levels of ethanol, acetic acid, and lactic acid
- The riper the cherries, the more of their own yeasts and bacteria they produce
- The yeast-bacteria cocktail in the coffee cherry is never stable
Which part of the coffee is actually fermented?
Only the reducing sugars: glucose and fructose. And these make up only about 20% of the mucilage.
The Short Answer
But what happens to the rest? The somewhat longer answer:
Once the cherry is pulped through a pulper, both seeds are exposed with the slime layer (mesocarp) surrounding them. It's this highly sugary slime that can be "fermented away." But let's look more closely at what this slime consists of.
Only during pulping of the coffee cherry does water come to the outside. Only now can the cherry lose water. Immediately after pulping, the layer now surrounding the coffee seeds has about 84% water. Where there's a lot of water, we also have high water activity, i.e.: dissolved substances in water move and react quickly. At this point, the first metabolic reactions are already taking place.
If we now subtract the moisture and look at the remaining components of the mucilage, we get the following picture.
The largest part of the mucilage consists of pectin (33%) and reducing sugars (glucose and fructose). 20% is sucrose/table sugar, i.e., complex, non-reducing sugars. The remaining 17% consists of ash and non-reactive material.
The Pectin
The pectin is the actual binding material that holds the slime together. We know pectin mainly from foods like apples, quinces, or tomatoes, which naturally have high pectin levels.
Through yeast metabolism, they begin to process the sugar in the mucilage and in doing so produce enzymes that drive the decomposition of pectins = pectinolysis. Pectins are polysaccharides, i.e., macromolecules, and are therefore not water-soluble. However, they can be split off with a little water, the so-called hydrolysis. The pectins remain in the fermentation tank in the water (here suspension).
What actually ferments is not the entire mucilage, not the pectin, but only glucose and fructose, the simple sugars.
If we pulp 1 ton of ripe Arabica cherries, that yields about 120 kg of mucilage still connected to the seeds. The drying process begins and if we imagine the water gone completely, we're left with 50% sugar: fructose, glucose, and sucrose. Of these, only glucose and fructose ferment.
In Summary, this means:
- 5% of the entire fresh mucilage are simple sugars. And only these 5% are actually fermented.
- The pectin is shed from the coffee seeds through hydrolysis, but does not dissolve in water.
Take-Home Message:
Only 5% of the mucilage is directly responsible for the formation of so-called aroma precursors (aroma precursors) in green coffee during fermentation. But these 5% are significant: with improper fermentation, defects such as stinker beans can develop. With controlled fermentation, however, specific flavor notes can be emphasized or even newly created.
3. Fermentation as a Flavor Enhancer
It's remarkable: 5% of the mucilage is directly responsible for the formation of so-called aroma precursors (flavor precursors) in green coffee during fermentation.
However, the term fermentation in literature is usually only used for the simplified demucilagination, and the influence on flavor is barely considered. Yet aroma precursors (so-called aroma precursors) are already formed in green coffee. The flavor of the finished beverage is largely already established in the green coffee.
- In other words: the quality and complexity in roasted coffee depends largely on the quality of the green coffee.
Roasting itself is responsible for the formation of volatile aromas, which are mostly created through a complex series of Maillard reactions, caramelization, and other thermal reactions. Through roasting, we influence the quality of the roasted coffee, but only to the extent that the green coffee allows.
How is good fermentation achieved?
By now it's become clear that fermenting the mucilage under controlled circumstances can make a coffee even better – but never must.
How well fermented coffee is depends on a variety of external circumstances. First, there must be awareness that this is not just a mechanical, but a biological process.
The following criteria are essential for good, controlled, and stable fermentation:
-
Climate
- Ambient temperature
- Humidity
- Sunlight on the fermentation tank
-
Water (if coffee is covered with water)
- Water temperature
- Water quality
-
Coffee Cherries
- Quantity
- Uniformity in ripeness
- Deformed cherries
- Rotten cherries
- Foreign matter
-
Hygiene
- Pulper
- Channels
- Fermentation tank
- Stirring rods
When is coffee fermented? And when not?
We now know that fermentation in coffee is not mandatory. Larger beneficios are geared toward efficiency and must process a lot of coffee in a short time, meaning receiving cherries, determining quality, sorting mechanically, pulping, weighing, and drying.
One of the largest beneficios I've visited since then was in Veracruz/Mexico. During peak season, up to 140 tons of cherries are processed there. Per day. From the moment the cherry is pulped until it lands in the dryer, only six minutes pass. There's no time for fermentation in between. Nor is it necessary, since today's pulping systems (despulpadoras) work with high precision and the mucilage removers (desmucilaginador) eliminate the mucilage (almost) completely.
- So it's economic reasons that hardly allow for more complex fermentation on a larger scale.
- But there are also climatic or local reasons: is there enough water, space, channels, containers, etc. on the property?
- plus historical reasons? Is there even awareness of fermentation?
- In northern Nicaragua (Nueva Segovia), the reposa, storing the cherries overnight until pulping the next day, is widespread. In the coffee zones in the middle of the country, Jinotega and Matagalpa, this is hardly applied.
The cost of wet processing with fermentation is quite high: it takes a lot of energy to run the machines. The water must be (and should be) recycled and the channels, pulper, and tanks cleaned thoroughly. Anywhere water is standing, there's a risk of contamination that can negatively impact flavor.
And what about the Naturals?
Dry processing (sun dried, natural), where the entire unpulped cherry is dried on the seed, is considerably cheaper on a large scale. But with specialty coffees, it's the exact opposite. As a rule, dry-processed coffees are more expensive, if they're high quality. The work invested in uniform drying of the cherries is enormous.
Honeys, Naturals, Anaerobics – various processing methods side by side on El Arbol, Nicaragua (J. Galea)
Special Fermentations are Boutique Merchandise
Anyone who's been to a coffee origin themselves has probably seen various processing models. I personally love asking producers "why" they do this or that. But the answer often comes up short and at the same time telling: "because I've always done it that way." Short on information because the technical content is low. Telling because it's obvious that much knowledge still needs to be transferred so producers can get even more out of their coffee.
Of course, there are counterexamples. The producer who can give detailed information about every step of coffee cultivation and processing, and knows which external influences can positively or negatively affect flavor, does exist. But they mainly exist in the specialty coffee world, may even be a trained agronomist, have studied abroad, or have had enormous exchange with visitors like us all.
We must never forget that the vast majority of coffee producers neither make specialty coffee nor have a clean pulper at home, and they probably grow coffee because they've always done it that way.
One of Many Coffee Realities
So when we talk about extraordinary fermentation techniques, we're unfortunately still talking about a boutique item:
cool, usually expensive, and rare.
However, at the World Barista Championships, for example, there are more coffees with special fermentation techniques than ever before. On the barista stage, it seems to have almost become standard that competitors bring specially fermented coffees for competition.
4. Fermentation with Starter Cultures
At the beginning of this article we already pointed out – what if we understand fermentation precisely and now deliberately influence it with yeasts and bacteria? Still an opportunity, or a monster?
Is coffee facing the same fate as Chardonnay 20 years ago? Voluminous, intensely aromatic flavor profiles that become increasingly similar, regardless of origin?
The Short Answer:
- there will be more and more intensely aromatic coffees
- every trend creates a countertrend
- forecast – in three years we'll land in the middle: targeted fermentation that isn't perceived as such in the final product
- the coffee clientele probably forgives less than wine drinkers – if coffee now tastes even less like coffee, then it's "not good coffee" anymore
- intensely aromatic coffees will probably never be the majority
And here's the longer answer:
Status Quo
We now know: mostly coffee fermentation is seen either as a pure mechanical function to detach the mucilage, or as a pool of dangers: a collection of risks lurking on the path from cherry to dried coffee.
If we consider fermentation as a great unknown, then we exclude its ability to also positively change flavors. But often today, a stinker bean in a cupping is directly linked to fermentation: "poorly fermented," "overfermented," the error lies in fermentation, not well executed. We need to be more precise here.
It's a reality that only in the rarest cases are "only the ripest cherries" picked (as baristas like to say at competitions).
The reality is: the large mass of delivered cherries is often inhomogeneous; unripe, half-ripe, well-ripe, very ripe, overripe; intact cherries (closed exocarp) and damaged cherries (e.g., split by rain).
Once the cherry is open and exposed to air, it accelerates uncontrolled fermentation. So long before the cherries are pulped and then supposed to ferment in a tank, defective aromas can already be in the seed.
The explanation for why a bean can be "overfermented" thus falls flat and shows an attitude that fermentation alone is responsible. But again: the starting material, intact cherries, is a basic requirement for delicious, defect-free coffee.
Targeted Fermentation with Isolated Starter Cultures
The starter cultures responsible for fermentation (yeasts and bacteria) as described above are already there – on and in the fruit, in the tank, in the air, on skin, on leaves – everywhere. However, the composition of these microbes is never constant; it's influenced by rain, heat, sun, hygiene, in short: everything surrounding the coffee.
These fermenting organisms use the pulp as an energy source and produce high levels of ethanol, acetic acid, and lactic acid, which can lower the pH value from the original 5.5-6° to about 3.7-4.6°.
When the factors pH value, temperature, and sugar content are correlated in combination with variety and quality of the cherries, fermentation can be deliberately initiated. Isolated yeast starter cultures can help achieve a reliable and consistent result.
"Hasn't research already been done on this?"
On a small scale, there are several experiments, but they're still limited. During my literature research for this blog series, I read (to my knowledge) the most relevant articles, but there were "only" about 20. Compare that to literature on aroma formation through roasting, and we're well over 100 published.
"And who uses yeasts for controlled fermentation?"
In an Gespräch with Lucia Solis, she said there are many more than one might think. In the past three years, she's conducted experiments on more than 45 beneficios in eleven different countries.
"Only many don't like to talk about it, as if it were something forbidden."
Lucia Solis, Coffee Fermentation Designer
But let's not forget: with cheese, wine, olives, salami, beer, bread – yeast is used in so many places.
Coffee Collaborative Source (CCS) reports in a Newsletter of Carmo Coffee from Brazil, which also conducted larger experiments with yeasts. One experiment was supposedly rated at 93 points – which in the specialty world is the million-dollar jackpot.
It's interesting to note that Brazil "had neither the energy nor the need to ferment coffee this way because it was time and resource intensive." "Brazil's coffee production was always geared toward volume and uniformity." Yet in this highly developed coffee industry with a focus on efficiency and innovation, such experiments met with great interest.
Fermentation experiments by coffee makers in Nicaragua
"Why isn't this widely available on the market yet?"
We can certainly discuss that in the comments section. It's not that this isn't being done. "People" just don't like to talk about it. Apparently, many more coffee producers use yeasts than is known. If there are multiple manufacturers of yeast cultures, then there are also multiple markets.
Another question would be:
are roasters ready to add a chapter to the coffee's story?
And then are consumers ready to embrace this new chapter? The Rösterei Stoll from Zurich launched a coffee from Burundi in spring 2019 that was treated with a yeast called "Cima" from Lalcafé Stoll describes this clearly on the packaging and was the first roaster in Switzerland to make it public.
Controlled fermentation with the help of starter cultures can create standardized quality. This can mitigate risk for the producer. Starter cultures can be yeasts or bacteria. Both can be purchased in isolated form.
In various scientific experiments, mainly conducted in Brazil, naturally occurring yeasts in isolated form were used: mainly those of the strains pichia and saccharomyces cerevisiae.
In another experiment (Pereira et.al. 2014), 144 wild yeast species were identified on and in the cherries. However, not all of them serve the purpose of deliberately influencing flavor. As a rule, the most promising ones are isolated and multiplied – "although a broad microbial diversity is generally observed, only a few numbers of species are usually selected. Thus, most of these indigenous microorganisms are probably not necessary to obtain a final product with high quality ", Pereira 2016.
When the yeast is added to the pulped coffee, the fermentation process usually starts faster and more intensively.
- The pH value drops,
- as does the sugar content, as it enters into metabolism with the yeast.
- The temperature rises due to the activity.
pH value, sugar content (brix), and temperature already tell us a lot about what's happening during fermentation and which direction it will develop.
Fermentation creates flavor notes that wouldn't otherwise be present in the coffee. You understand this best by tasting the same coffee in different processing methods side by side. However, it's rather rare to have the opportunity for such a direct comparison. Has Bean from England, for example, maintains close contact with its producers and thus has the opportunity to obtain different processing methods. It's worth ordering various coffees from the same farm.
Multiple studies show that the peak of yeast activity is reached at about 40 hours, so it metabolizes many bacteria and shortly after almost completely dies off (48h). As already described, not every yeast has the same properties. There are different strains, of which there are again different types.
Like with wine or beer, there are different types of yeasts in coffee too. In other experiments from Brazil (Ribeiro et.al. 2016), different yeasts were used and observed over time.
The studies concluded that
- Flavor differs significantly depending on the type of yeast used. Always compared to the control sample, which was fermented with wild yeast
- The yeasts used produced different levels of acetic acid, alcohol, or lactic acid
- The same yeast didn't "dock" equally well with different varieties
- When comparing yeast-inoculated premium coffee vs. sample without yeast, both samples scored equally well (89 points on the SCAA scale), but with different strengths
Particularly points 3 and 4 are an exciting and important message.
On Point 3:
The coffees were fermented for 12 days with the same amount of yeast. The coffees were of the varieties Mundo Novo (MN) and Ouro Amarelo (OA). The populations of the yeast cultures were different at the end of fermentation: only 25% "residual yeast" for MN and still 74% for OA. This means that more intensive metabolism occurred with MN.
In the sensory evaluation, the following picture emerged:
| Wild Yeast | Added Yeast | |
| Mondo Novo | 84.25 | 80.13 |
| Ouro Amarelho | 81.38 | 83.25 |
- Adding a specific yeast to Mondo Novo reduced the coffee's flavor by more than 4 points
- Mondo Novo had much higher metabolism with yeast – but that doesn't mean high metabolism always has positive effects on flavor
- The opposite is true in the case of Ouro Amarelho: adding the yeast was able to improve the coffee by almost 2 points
So we learn:
- Yeast is not all the same
- The choice of yeast is crucial for the sensory quality of the coffee
- The variety probably has a greater influence on fermentation potential than previously assumed
Where to go from here? This question is actually almost inappropriate, because: from which point are we even going to go forward now? Should we continue to "play" with fermentations or really experiment?
More Experiments – Structured
Earlier we mentioned various research approaches. Here we need to distinguish between those experimenting on the farm and those providing scientific backing.
The vast majority of research to date has been conducted in Brazil. The reasons are obvious: as the world's largest coffee producer, there's great interest in strengthening its position through innovation and making good quality better and lower-quality coffee more enjoyable. The driving forces today are still universities working with producers to create new knowledge. Private initiatives, at least known ones, are still in the minority.
Outside Brazil, we mainly read about innovative privately-owned beneficios, or even more rarely, exporters (Caravela, Project Origin) conducting fermentation experiments. These experiments result in special coffees that can then be marketed as "Carbonic Maceration," "Black Diamond," "Beaujolais Method," "Lactic-Acetic," or XY-Fermentation.
Fermentation experiments must be closely monitored. And especially at the beginning, every few hours. So it often happens that many experiments need to be checked at night.
Competitive Advantage and/or Communication
So we see two approaches:
- the structured, reproducible, aimed at creating knowledge and therefore inclusive type of research that should be made accessible to a majority of producers
- the private, mostly driven by "experimental enthusiasm" type that creates new, even more complex flavors for exclusive markets (e.g., 90+, La Palma y el Tucan)
The pioneers among the experimental creators a market that has been growing enormously for a few years. The insights remain exclusive because they create a competitive advantage in the increasingly differentiating green coffee world.
Boutique producers rarely let others in on what exactly happens during coffee processing. For fermentations to be reproducible, significant investment goes into this process. Therefore, it's not surprising if a special method is understood as intellectual property.
Intellectual Property or Freely Accessible Knowledge?
At the same time, however, this shows so much potential where a large mass of producers could go, if standards can be formulated through science. A first literature review of the current research showed that today's results are very locally influenced. What would be needed are more general, universally applicable recipes for producers.
For the large majority of coffee producers to gain access to this knowledge, we need even more research and more communication about it. We've described how strongly the coffee variety, a strongly local property, influences flavor. The local character will therefore persist and it will be difficult to imitate a flavor profile by copy-pasting methods.
5. ZHaW Zurich x Coffee Makers – Research on Finca Santa Rita
When we say that more research and communication is needed, we want to be an example with our Finca Santa Rita. We want to promote exchange. It's at the heart of our vision to create more intense exchange throughout the supply chain. We want to operate a farm that can also become a place of exchange for producers in the region. A place where something can be learned – for example, about fermentation.
Barbara Beck from ZHaW, 2019, on Finca Santa Rita
We took the first concrete step toward "creating knowledge" in 2018, when it became clear that we received research funding from InnoSuisse for a preliminary study together with the ZHaW. Many thanks for the networking through Peter Braun from Swiss Food Research.
Together with the team of Susanne Miescher-Schwenniger from ZHaW Food Biotechnology, Susette Freimüller Leischtfeld, and Barbara Beck, as well as the team of Chahan Yeretzian from Coffee Excellence Center, and Sebastian Opitz, we were able to present the first results in June 2019.
Barbara Beck as a biotechnologist presented her results, which she was able to achieve based on her field research in January 2019 on Finca Santa Rita. She focused on the development of yeast populations and their behavior in our two standard processes that we apply on Santa Rita – the tradicional and reposo methods.
Barbara Beck collected yeast strains, microbial populations, and analyzed sugar values, pH, temperatures, etc.
Sebastian Opitz as an analytical chemist examined the influence of fermentation methods on flavor. The processed green coffee beans and coffee cherries from Santa Rita served as the basis for his findings.
We're thrilled about this collaboration and proudly present here the first results of this multi-disciplinary experiment.
Beck, Freimüller, Opitz, Yeretzian, Miescher Schwenninger, 2019Summary of Results
- Beck: longer contact time between cherry and seed (no pulping) multiplies the existing yeast strains. This is the starting point for more intensive fermentation (e.g., reposo)
- Opitz: the reposo process lowered the coffee's pH value and increased citric and especially quinic acid. These differences were also clearly evident sensorially.
Where is the Journey Going?
More experiments with more methodology, so that we can eventually say with confidence: what we do is driven more by knowledge and experience than by chance. We're paving that road now.
But with our farm, we're only a mosaic piece in a discourse that's increasingly rolling.
The discourse on flavor-building fermentation will show how close or how far apart origin and consumer market really are.
For they've never been more tightly linked. Until now, it's mainly stories that form the bond between the poles, meant to show our consumers what exactly happens where coffee comes from. We should probably expect many more coffees in the future that become so characteristic through their flavor alone that they speak for themselves. But the big question remains: how far this modern tool can seep through to the bulk of producers.
