Fermentation in Coffee With Lucia Solis

Lucia Solis was one of the first people who made me passionately curious about coffee. As a fermentation and processing specialist, she helps people all across the industry understand the role of microbes (like yeasts and bacteria) in shaping coffee’s flavor and characteristics. This topic can be complicated, but Lucia shares her expertise through education; workshops; and by hosting her own podcast, called Making Coffee.

Fermentation is a nearly universal step in coffee processing. Coffee beans are the seed of a cherry, and fermentation helps remove all the mucilage around the seed so it can be dried, roasted, and consumed. But fermentation does so much more than that. In coffee, the process works slightly differently than in other fermented foods, and folks like Lucia are using fermentation not just to uncover and express exciting flavors, but as a powerful tool to give producers more consistency and resilience to climate fluctuations.

This episode does it all. We break down what the fermentation process looks like and how we’ve historically misunderstood its potential. Towards the end, we also get deep into niche coffee debates and scientific conversation. Here’s Lucia.

Ashley: I was hoping you could just start by introducing yourself.

Lucia: Yeah, sure. My name is Lucia Solis and I’m a former-winemaker-turned-coffee processing-specialist.

So that means I studied winemaking at UC Davis and went to working in wine in Napa Valley. I did that for almost 10 years—like nine-and-a-half years—and then I switched over into coffee.

I came in through coffee sort of in the back door, from the microbiology/fermentation side, and now I live in Antigua, Guatemala, where I was born. So I'm kind of back full circle. Even though I was educated and raised in the United States, I was born [in Guatemala], my family is from here, and when I wanted to be closer to coffee post-pandemic, my husband Nick and I decided that we needed to get out of the U.S. and just be much closer to coffee farms.

We live on a coffee farm now; we process coffee and I go back and forth between education and processing. I hold workshops and just generally do coffee education for coffee producers. But, of course, anybody in the coffee industry, all along the chain, is welcome to enjoy fermentation, microbiology—which is pretty niche, so you have to be quite a coffee enthusiast to want to know about coffee microbiology. But that's basically what I do: I try to focus on education.

Ashley: It's so funny that you have to be really into the nitty-gritty of coffee to be focused on some of the things that you cover in your workshops, or on your podcast. You also host a podcast called Making Coffee—but you yourself weren't really a coffee drinker until after you started getting involved in fermentation with coffee, right?

Lucia: I would say I was a coffee professional who didn't drink coffee, meaning that I made my living, like I was able to pay my rent and I paid my expenses, from working in the coffee industry while not being a coffee consumer.

I didn't drink coffee regularly as a part of my life and my ritual until my 30s, because I didn't come through coffee by loving coffee. I came in through loving microbes.

My first love is microbiology. I was, 13, 14 years old in chemistry class, biology class in high school and I was just like, “This is it. This is the thing.” I knew very young that this is what I wanted to do with my life and that I would somehow—I don't know—it would be something that my life would be involved in.

And then again it took me to wine, and now I'm in coffee, and who knows where I'll end up in another 10 years? But yeah, it took me a long time to like coffee, to make it part of my life. That wasn't really what drew me to it.

Ashley: Did you grow up with coffee in your life?

Lucia: So being born in a coffee-producing country—it's a big part of the culture in Guatemala to grow coffee, not necessarily to drink it—I surprisingly had very little contact with coffee.

I would say the way that I grew up with coffee is because my mom is a coffee lover. And she's somebody who had a really strong coffee ritual to make her lattes. We had a very nice espresso machine in our home, and she makes her daily latte.

I think I, just being like a young, jerk, teenage daughter, really rebelled against anything that my mom liked. And she was so into coffee that I was like, “I'm so not into the thing that you're into.”

So I was very anti-coffee-culture, like at least that consumer part of the culture, for a long time, even just working in it, until I finally fell in love with it. So coffee was always around.

I grew up in the Bay Area as well. So I had really wonderful cafes near me. We had Ritual and Blue Bottle. It was just like something really close by that we could always go to, so I loved the cafes, like I liked that part of it, but I just wasn't into coffee and I'm now, I'm fully converted.

Ashley: How did you make the jump from winemaking to coffee?

Lucia: So I wasn't looking to make the jump. I was really happy making wine, living in Napa Valley—and this opportunity came to me.

I was recruited by Scott Laboratories who is—they are supplier of all kinds of wine supplies, basically. So you can buy your corks, you can buy yeast, you can buy enzymes, all kinds of filtration media. They sell a lot of different things that you need for winemaking, and so I was a customer of theirs for like six or seven years so I knew the owners really well, we were friends. There's lots of interaction.

This was in early 2013, that Scott Laboratories was looking to expand their yeast sales from wine and beer into other markets, so they wanted to expand into coffee and into cacao—this was like a pet project of one of the owners, because he worked a lot in the wine industry in Baja California and Mexico.

So he saw that Mexico has both wine and coffee and he just started getting interested in it and so he's like, “I want to do this,” but he couldn't do it. “I need somebody who knows fermentation, who speaks Spanish, who would be willing to open these doors.” And [he] offered me the position.

For me, I was like, “I like what I'm doing—I'm good.” I initially said no to the offer, but he was like, “You know, just think about it. I think you'd be really good at it.” I had a really wonderful mentor, Michael Silacci, the winemaker of Opus One, where I was working, who I approached about this.

I said: “Alex, Scott asked me if I would be interested in this position. What do you think about it?”

He agreed with Alex. He's like, “I think you'd be good at it. I think it would be a good opportunity for you and if you don't like it, you can come back.” So he made it really easy for me to take a leap and to accept the offer.

In the first years in, 2014, 2015, I was doing both: I was still working in the wine industry in Southern California, like San Diego area and Mexico, and then other times I started traveling to coffee mills in Central America. I'd go to Guatemala, go to El Salvador, Panama, and Costa Rica, and start doing coffee fermentations with some of these wine yeasts from the Scott Laboratories profile.

And just to be clear: the Scott Laboratories who was a yeast supplier is not the same Scott Laboratories that developed the SL varieties in Kenya. So those are, coincidentally, two Scott Laboratories who were doing coffee things early on but have nothing to do with each other. It's just a funny coincidence that they have the same name.

So that's how I got into coffee. That's why I mentioned sort of coming in the back door. It was about fermentation and microbes, using my skills in fermentation to just try to do this coffee flavor project for this company. Then in 2016, I stopped working for them and I went independent. So now I'm an independent coffee consultant.

But that was really rewarding work and that set the foundation for trying a lot of different commercial yeasts in many, many different—into 13 different countries, a lot of different mills, trying to match certain yeast strains to coffee varieties and different altitudes, different conditions, different varieties. So I got to do some of that work which was really cool—but it wasn't research. It was more application.

Ashley: That's an interesting distinction, and I think something that you're really good at is using words really intentionally.

I also think that you are a very clever metaphor-maker, and one of the metaphors that I heard you use on one of the episodes of your podcast is that having fermentation on coffee farms and only really thinking about fermentation as a vessel to remove all of the layers around a coffee seed is like having an F1 racing car and using it only to buy groceries.

So with kind of that framework in mind, let's talk about what fermentation is.

I think for a lot of people maybe listening to this show or even myself, I feel kind of inept really understanding what fermentation’s possibilities are.

I kind of understand it, I think, from a very rudimentary level in certain aspects: like I obviously have some background in coffee, so I kind of understand a little bit of the nitty-gritty. But as the word fermentation, I would say becomes—I'm going to use quotes; we can't see each other right now, so know that I'm using air quotes—”vogue,” and it's becoming something that roasters put on bags and start using all of these different terminologies for, like co-fermenting or anaerobic fermentation which you have mentioned is an oxymoron—or not an oxymoron—it's redundant.

Maybe we can start to peel some of the layers back on that and talk about what fermentation is and how we've looked at fermentation historically in coffee. So I know that's a big question—maybe we can start kind of really fundamentally, and talk about what is fermentation in coffee.

Lucia: Sure. So one kind of warning for your audience is if this topic is interesting to you because you have seen it a lot, or you just have a latent nerd inside of you that enjoys these topics—one of the the themes that will always follow us into this topic of fermentation or microbiology is that it is incredibly complex and incredibly nuanced.

If you are a person who really likes certainty and clarity and black-and-white, then a lot of these conversations, especially around the topic of coffee, are going to feel very uncomfortable, because a lot of the answers are “it depends” and “maybe” or “if this, then that”—like, they're very, very sticky and very messy.

That's where I get a lot of my ideas for the podcast, or a lot of my communication comes from like untangling this, like, giant ball of yarn. So I just wanted to say that this is very normal, to be confused.

But your very simple question of what is fermentation: The way that I define fermentation is from the microbiology perspective, where it's a metabolism. It's a way that microbes, like yeast and bacteria, get energy.

In coffee, these microbes are breaking down the glucose that is found in coffee fruit and they're metabolizing it to get their energy, and the byproduct, the happy accident, is that by doing that, they create these metabolites, these flavor precursors that can get into the seed and that later, we can perceive them in our cup—but it's just the way that these microbes get energy.

I think one of the things that happened is we didn't talk about fermentation for a long time because we really focused on the roasting element giving the flavor of coffee. I think a lot of people were really surprised that coffee was fermented, because we were used to thinking of fermentation in our breads and our beer, in our wine and our cheese and our yogurt.

The other clarification that I like is that, yes, coffee is fermented, but I do not describe it as a fermented food in the way that those other products that I mentioned are fermented foods. If you have grapes—if you don't have a fermentation, you will never have wine. If you have milk and you don't have a fermentation, you will never get cheese or yogurt or kefir or some of the other products.

Coffee: If you don't ferment coffee, you will still get coffee at the end of the day. The fermentation is completely unnecessary for you to enjoy your final beverage—and yet, almost every coffee of all time has some element of fermentation, because these microbes are in the air, they are on the skin of the fruit, they're in the soil, they're in our water, they're on the equipment, so you can't really escape them.

We can't get away from the fermentation. It's both probably every coffee you've ever had has had some level of fermentation as part of it. You have to try really hard and use special equipment to not ferment—the default is fermentation. But also, you can completely skip the fermentation and just have coffee. So I think that also helps us kind of keep the fermentation element of coffee in context, meaning it can be really important and it's also completely irrelevant in another sense.

Does that make sense?

Ashley: That makes total sense. So let's maybe even try to clarify further what we mean by the idea that coffee doesn't need fermentation.

So you said it really well with the idea that you have grapes; you have grape juice—you're never going to get wine without fermentation.

I think you used one example in one of the episodes of your podcast I was listening to, where the only way you could really get coffee without fermentation—and even so, this is not even totally right because fermentation happens just by, like ,you touching a coffee cherry and there's microbes everywhere—is if you remove…

So coffee—most listeners know this, but just to give a little bit of an overview—coffee is the seed of a cherry, and there's all these layers around the seed that we want to remove, essentially, from that seed to get to the thing that we want to drink. And to remove all of that stuff, usually farmers use some level of fermentation to get some of that stuff off.

If you were to use mechanical processes to remove all of that stuff to get to the seed, then maybe you could say that that coffee wasn't fermented. I think that that was the example you used. I think you even tried to think of another way that coffee could not undergo fermentation and then you were like, “Nope. That's it actually.”

Lucia: Exactly like you say—that the fermentation's role in coffee is to remove this mucilage layer, this thick, gelatinous, pectin-rich sugar layer that is an obstacle for us to get into the seed. Because if you don't deal with that layer, then your seeds stick together. They clump, they can get moldy. You can't move on to the next phases of drying and roasting the coffee if that stuff is still there.

Fermentation was actually a very sophisticated—or is a very sophisticated—way to describe something that is not very sophisticated at all. So by saying producers are doing a fermentation or applying a fermentation actually implies a lot more control and a lot more intention than is historically or traditionally found in coffee processing.

So what it was is you get these fruits, and again, you have to get to the seed. So what most producers can do, or do even still today, is they remove the—it's called pulping the coffee—you remove the outer skin, the cascara, and then you have this mucilage layer and basically then you do nothing. You just wait.

The coffee gets put into a tank and then left alone completely. It's not mixed. It's not stirred. It's not touched. You just do nothing, and that's the fermentation, and then eventually the coffee is basically rotting, right? So the microbes are eating all of that mucilage layer and then eventually the seed is clean and then you can go dry the coffee.

I think that's also really funny, of this picture of like, somebody intentionally fermenting—but the reality is like, oh, you just like let the coffee rot and don't touch it and that gets your seed clean. So I think that being able to use this word, this very sophisticated word is—like we're sort of getting lost from the beginning.

Ashley: What your explanation sort of implies is that, historically, fermentation was not a very intentional process.

I think even you've said that fermentation was almost viewed as like a step that you had to get over. Like, “Oh I have to do this nuisance-like thing because I need to get all this stuff off the coffee seed. This is actually just taking time.”

How has the historical understanding of fermentation—how did that affect how we understood where flavor comes from in a coffee bean?

Lucia: So the other thing to mention—with this idea of how fermentation was used historically—is that the role was to remove the mucilage from the seed and move on.

There's consistently, historically, been a push for coffee producers to ferment as quickly as possible and have that rapid turnover rate in their production. Then, on the other side, on the consumer side, we are used to thinking about fermentation as a place of flavor enhancement from these other beverages, from these other examples—and that longer fermentation times are better. There's just a really big disconnect between how producers have historically used fermentation and thought of it and then what consumers are expecting from their fermentations.

So because the push for coffee producers has been fast fermentations—it wasn't just being able to get paid more quickly. They also noticed that, well, if they didn't wash the coffee as soon as possible, if they waited, if they left the coffee basically rotting longer, then it would take on the flavor of rot. For many coffee producers still today that I talk to, the word “ferment,” like fermented coffee, means rotten coffee. It means defective coffee.

They still associate this word with a negative, and yet they're talking oftentimes to consumers that are like, wanting a 500-hour fermentation, or asking for these really novel processes, not realizing they're not really speaking the same language and often have opposite goals.

One of my guiding lights and one of my favorite quotes from Danish physicist Niels Bohr is that, “The opposite of a profound truth is often another profound truth,” so the fermentation could completely damage your coffee and give it a really, really nasty flavor—and that's where most producers stopped and coffee just moved on. The same tool, depending on how you're pulling the lever, can get you different things.

There’s another quote that I like a lot, but it's this idea that we often talk about the same things but we have not yet agreed what we're talking about. So we're all talking about fermentation: Producers are talking about it, consumers are talking about it, educators are talking about it. But we all have a different definition.

For some people it's this thing that creates flavor. For other people, it’s the thing that ruins my coffee. For other people, it's basically rot, but we're still using the same word. So going back to the earlier point about how, to me, words matter, because I just see us kind of going around in these circles. It's really hard to move forward when again, we haven't even agreed on the baseline.

Ashley: I want to ask you more about words because now I can't remember if I said this on record or if I said this to you before we started recording—but you were one of the first people who really made me think about terminology really specifically and how important it is to define terms and make sure that we understand what people are talking about when they use certain words.

Another thing that I saw on your website when I was doing research for this episode was that fermentation can kind of work in both ways, so you are—no, this isn't from your website. Actually this is from an interview I did of you in 2018 that I forgot that I did.

But you talked about how, for one farmer, really manipulating the fermentation process can be really beneficial if they're in a cooler climate and their fermentation's taking way too long. On the converse, if someone is living in a very hot climate, fermentation can also help them slow down that process or do whatever they need to do to circumvent what could happen if it's too hot and their coffee goes bad too quickly.

It's really interesting to hear you reflect the idea that fermentation lives in both of those dualities, if that makes sense.

Lucia: Well, not just both of those dualities, but many, many more.

We're using the same tool of fermenting the coffee, liberating the mucilage, and in those two scenarios, they're opposite climates and potentially opposite goals. But we're still using the same tool. We can use a fermentation to buy us more time in the hot scenario, and maybe elongate the fermentation so that you can get more impact of flavor [in the other]. Think about it like a soup—you want those flavors to marinate and if you can, simmer it for longer. You can get more flavor development.

In the cold sense, there's diminishing returns—you will plateau, and more time doesn't always mean more and more and more and more and more flavor. In those situations where I've had clients, coffee producers that have coffee mills or farms in incredibly cold climates, really cold nights, they really struggle to get their fermentation. This is frustrating for them because space is limited and so if they're not able to turn over their tanks, they could maybe not have enough space for the incoming coffee cherry, meaning that it's either going to rot on the vine or rot on the tree—then that also impacts their economic viability because they're not taking advantage of all of their resources. So there's a lot of reasons why you would want to cut down your fermentation.

The other reason for this particular producer that I use in the example, his fermentations were taking so long and the mucilage was so stubborn, they would wash the coffee and then it would kind of stick back to the coffee seed and they'd have to use even more water.

By doing a fermentation in a different way, using a particular yeast strain that was able to dissolve the mucilage much more efficiently, he was able to reduce his water usage by half, just by changing the type of yeast that was in his fermentation tank.

This tool can be used in very different climates for different varieties for different goals and I think, too often, we think of fermentation in a very narrow way, and I just love to bring these examples to open up the multiverse of all of these different things that we can do with yeast—the least interesting of which, to me, happens to be flavor.

Ashley: Of the ways that I was able to experience some of your work is I went to a workshop that you did called ‘Worms and Germs,’ and it think it speaks to that idea of flavor kind of being like, the last thing on the list, in a way.

One of the coffees that you had us taste was, I think it was [two of] the same coffees. One was grown at a very low elevation, and elevation is one of those things that we prize in coffee—we talk about it constantly: “This was grown at 2,000 meters above sea level,” or what have you, and that's a marker of quality generally.

But elevation is kind of a finite resource—and then there's also kind of the nexus of climate change which I'm sure fermentation could really be a useful tool in.

But the coffees that you had us taste were so markedly different, and it was really interesting to have you talk about how fermentation can be an enhancer for these finite variables. Essentially it's almost like looking at a science experiment: You have your independent and your dependent variables, and there are certain variables that are fixed, that you can't change.

I wonder how you approach your work when you're working with a farmer. How do you take in everything that you're experiencing on a farm to come up with a solution that makes sense for them?

Lucia: I love that question. But first I want to kind of address this idea of flavor diversity, because I think it speaks to one of my personal pet peeves, which is this idea of a coffee hunter. This idea of going and finding these gems out in the wild.

I think that the old-school mentality was the only way to get flavor diversity, to have a broad range of offerings for our coffee consumers, is to go to all of these different places and to make sure that your menu has a coffee from Kenya and a coffee from Sumatra and a coffee from Guatemala and a coffee from Colombia, because that was the diversity of flavor you had to have to be that different.

I think that now what we've opened up with processing and with the world of microbes is that you can get a microcosm of flavors from the same place. You can take one coffee and treat it differently, process it differently, and then also using different microbes in your fermentation or the way that you dry it, you can get this rainbow of flavor in one place.

I think that's a really important tool for a lot of producers to be able to use, is that you have the power in the way that you treat your coffee to get all of these different flavors. That kind of dovetails into the second part of your question, is how I approach designing fermentations for my clients.

First, usually I spend a good amount of time at their facility—I try not to do as much virtual consulting. I really like to be on the ground and understand their limitations, whether it's access to water, whether it's access to labor, how much climate change, how much pests and diseases are pressuring the area. Then I like to reverse-engineer the simplest possible protocol that I can.

My designing strategy is very minimal because for me, the goal is reproducibility and scalability. One of the biggest complaints I get from coffee producers is, “I do the same thing every time and I get a different result. I'm picking from the same farm, I'm fermenting for the same number of hours in my same tanks and then when I go to taste the coffee they taste differently.”

That makes a lot of sense when you understand microbiology and where some of these contaminations could be coming in and the role that temperature and pH play—that's kind of what I helped them unpack. But I think that's been part of why we've needed the coffee hunter, is because we haven't given producers the tools to know how to consistently reproduce their good results. Does that make sense?

Ashley: That totally makes sense. It makes me think of the idea of, how does one determine the value of what they have, and if they can't reliably and predictably understand what a coffee's going to taste like from one tank to another, from one harvest to another? That severely limits the power of a producer to create value, for the value to start there.

You've talked about this on your podcast, too—that the coffee supply chain works in reverse in a very bizarre way: That a lot of the way that we value coffee or the way that we dictate—I don't want to say trends, but just the way that things happen—comes from consumers and roasters versus coming from the farmers themselves, and I have to imagine unreliability is one of the key reasons. I mean colonialism is too, but the unpredictability of a harvest is probably one of the big reasons why that process happens in reverse.

Lucia: Absolutely and yes, unreliability, but unreliability because of colonialism meaning that these were new, novel crops that were introduced into unfamiliar environments, to unfamiliar people who don't have the decades or centuries of history to know how to treat disease, to know how to actually process this.

One of my pet peeves of comparing coffee and wine is that we don't often acknowledge that with wine growers, there's a lot of cultural and historic knowledge because of how long the grapes have been growing in that certain area. There's a lot of power that the growers have because they know their product really well and wine definitely works from the producer out—the price of the wine bottle depends on how much you paid for the grapes.

But the same is not true for coffee—the price of the coffee bag, of roasted coffee that you buy, is rarely proportional to what the initial coffee cherries cost or what the producer was paid for that. So I think that when we try to compare coffee to wine, we don't realize like this complete power disparity that grape growers have that coffee producers don't have. And when we use that analogy we kind of provide cover and then we can kind of overlay this very romantic idea of the coffee grower because maybe we know some winemakers or we see like that wine style and it's just not true in coffee.

I think that it lets us talk about the lovely and kind of like romantic and fun things about wine without addressing this systemic power imbalance that came from this crop being forced on a lot of people and oftentimes pushing out their native crops and pushing out their subsistence crops just to grow coffee for other people. So like, it's kind of icky.

Ashley: Yeah, it’s definitely icky. I want to talk a little bit about the power of fermentation when it comes to climate change, because one of the things that it feels like we talk a lot about in coffee but we maybe necessarily haven't faced in a really tangible way is that coffee is going to change drastically.

Coffee has already changed drastically. So have you seen fermentation playing a bigger role as climate change continues to affect farmers?

Lucia: Yes, and I think actually I just lived this with a new variety that is a hybrid. It's an H1 variety here on the farm in Guatemala, and my usual microbes are having a really hard time fermenting this rust-resistant variety.

I'm not a geneticist so I'm not sure about this, it's just my observation, but these hybrid varieties tend to have thicker mucilage—at least the one that I'm working with—and it's taking much longer for that mucilage to dissolve, so it kind of screwed up my [plan].

I had a chart: I ferment for 36 hours and then I go to the patio and then I know how much cherry I can receive. I know how many people I need to be on the patio to be raking this coffee and moving it and because this mucilage was just behaving in a way that I had never encountered in 10 years, it was taking twice as long and it just [sparked] this chain reaction of screwing up when I could receive cherry and how much space we had on the patio.

We figured it out, but I was really surprised that change was so significant that I saw it in my fermentation tank. So I think that the microbes that have been traditionally fermenting coffee that are just spontaneous and wild may not be able to keep up with the new varieties that we need, because of the more disease pressure and climate change pressure for coffee producers.

I think that's something that maybe people haven't thought about and I hadn't seen it until this very year working in the mill.

Before we wrap up, I want to say that there's a way that we're talking about this that I get really excited about in terms of the identities of certain yeast strains and what flavors they can produce and how we can marry the yeast strain and the coffee variety into creating some flavor.

I could see how some people could be kind of uncomfortable about that and thinking that are we just doctoring coffee and creating flavor that's dishonest.

Because a lot of the conversation that I do see is this idea that we value transparency and really wanting to exemplify the taste of the place, and I have many episodes about terroir—that's definitely a topic that I really like to talk about. But in a nutshell, I understand how it makes people uncomfortable, but I'd like to make a little bit more effort to talk about how yeast works and that it's not creating a flavor that isn't there.

It is part of its metabolism to consume the sugars as well as other minerals and nutrients that are in the coffee medium and then its byproducts just happen to be these aromatic flavor precursors. And because yeast and bacteria are completely part of the skins and the identity of these coffee cherries—I don't think that they're two separate things, the same way that we humans can't really separate our bacteria DNA from our human DNA—like, we just are our microbiome.

I do still think that you can have transparent coffee that is honest coffee that is fermented in this way and that we're not like, faking flavor or we're not creating something that's not there. It's still a very natural process which is different from perhaps an infused term where you are maybe drying with citrus rinds to try and get the aroma of citrus into the coffee seed.

I'm not saying that infusion doesn't happen. But fermentation is not that infusion—fermentation is flavors that are generated from a metabolism and not like essential oil drops that you're putting into the tank or something like that. Do you think that's clear?

Ashley: I think that is clear. I'm trying to even go backwards a little bit on parsing out that tension because I think that that's like, a super niche tension. It's one that I see all the time—but it's not necessarily something that, as a consumer, I think you would see, so I'm trying to unpack it a little bit.

I would say if I'm trying to explain it, and maybe you can correct me on this, I would say in, like, the last five years there has been “concerns”—again in air quotes—about things that we add to coffee.

It seems like in the muck of all of that, fermentation has kind of been thrown in there and there has been questions about, are we manipulating the flavor of a coffee by adding certain things—like you were saying, like citrus rinds to the drying beds. And fermentation is not that.

I think it gets confusing for people when they see like, pineapple processed or something like that which is, if I'm right about this—I think I'm right—is a process called co-fermentation where fruit is thrown into a fermentation tank to aid along in the process, because pineapples have their own microbiomes. But that's not there to necessarily infuse this thing with pineapple. It's there to be part of the fermentation process—does that make sense?

Lucia: Exactly, and I think that that is a really good point to remember, is if you add fruit at the fermentation stage—if you add mangoes, if you add strawberries, if you add pineapple to your fermentation at the stage where the coffee still has all of its mucilage on there—all of those fruits are just providing like more fuel. It's more gasoline for the fire of fermentation.

But you're not going to get a one-to-one flavor. Your coffee will not taste like pineapple. It will not taste like mango if you put mango at that phase. I do think that a pineapple fermentation is more confusing than it is helpful because then it gives that impression and then you have consumers—you're kind of priming them to be like, “Do I taste the pineapple, do I taste a tropical flavor?” which is not directly translatable.

This is a problem that we have in science, is our words and our terminology are pretty bland so people don't want to use some of these words.

I think you’re right: For consumers, maybe this is not a concern. It's more for coffee industry people in the middle that I see a lot of this resistance to the purity like pure coffee or transparent coffee and a big resistance to…

Ashley: Right? And to be clear, this is a hot topic in the niche niche parts of coffee—people get very upset about this.

Lucia: It's true, and I'm really glad that it is such a niche part of the market and that most consumers don't care and are just interested in good-tasting coffee, because I really think that's, at the end of the day, that's what's important. Does your coffee taste good?

I don't know that we need to moralize or demonize some of these processes. It's just coffee guys. It doesn't need to be as intense.

Ashley: I do think you made a good point, though, when you talked about the words like “pineapple co-fermentation” or something like that as fermentation—again, I'm going to use air quotes—becomes more “vogue,” even though fermentation's been around forever and a lot of these processes like co-fermentation have been around forever. Even though I've seen on websites being like, “This is a new process.”

It's like, okay, well, it's maybe new to you, but it's been done for quite some time. There is still a lot of confusion about what's actually happening with my coffee, because these words don't really have any sort of scientific definition within our industry specifically that we all agree on. Again, going back to this idea that you were one of the first people I've really heard talk about the use of words and how words matter and how our inability to land on like one definition for a thing means that we're all probably talking about either the same thing with different words or talking about different things with the same word.

So for consumers, when they look at a bag of coffee and they're like, “What does anaerobic fermentation mean?” or, “What does carbonic maceration mean?” like how is a consumer supposed to interpret like, what's on a bag of coffee essentially implying some sort of fermentation process has happened but like—I don't know. How do you pick up a bag of coffee and even decipher what's going on here?

Lucia: You know, and it's funny, too, because I mostly work with coffee producers. But because of the podcasts and because some of the presentations and work that I do, I also get to talk to a lot of roasters. So like, I will look at my inbox and I'll have messages from coffee producers saying, “Oh a roaster asked me to do carbonic maceration or this anaerobic process—what does that mean?”

And then I have, in that same space, a roaster saying, “I received this carbonic maceration, this aerobic coffee from a producer—what does that mean?” and I'm just like, both sides are not talking to each other. I think that both we don't have enough words for coffee because it's a young industry, so we haven't developed that vocabulary, and then also we are being very loose and very sloppy with how we're naming things.

There needs to be a balance, and I think right now we had way too few words and now we have a lot of words and I think we just need to—we're just in this messy middle, and we need a little bit more time for things to calm down and then coalesce into a vocabulary. And I know that there are people that are attempting to have dictionaries and lexicons and people really want this. My concern is that most of these efforts have been from the consuming and roasting side, and I don't know that there's enough balance within the whole chain that everybody's voice is being heard.

I think there's also a cultural context where different cultures also have different meanings that's not necessarily something that we need to untangle and demystify. It’s just saying, “Oh, what does this mean for you, a producer in India? And what does this mean for you, a producer in Guatemala? How are you using these terms?”

Because they could be very different. One example I'll give you really quickly is double fermentation. So in Kenya, “double fermentation” usually refers to, in the first phase, the coffee cherries are pulped—so the skin is removed. There's a dry fermentation, meaning it's just in its own moisture. There's no additional water for maybe the first 24-ish hours, and then there's a second phase where the tank is completely submerged in water and then that's the second fermentation.

So that's a double fermentation, and that has a very specific flavor profile. In Colombia, a lot of producers are using the term “double fermentation” when they keep the coffee cherries whole, intact, for one to three days, maybe a week, and then they pulp the cherries and then they do a second separate fermentation in parchment, in just the mucilage, and that has a completely different flavor result—and yet a consumer on a bag will just see “double fermentation.”

I don't think that there needs to be one universal fermentation and Kenya needs to either adopt Colombia's or Colombia should adopt Kenya's. Each country can have their own definition and maybe it's just asking more questions, if you care.

If you just find a flavor that you like, go for it. But if you do care, I think there's a lot more questions that could be asked.

Ashley: I mean I guess I would put it on roasters to be clear about what they mean by those things too. But maybe that's implied in that.

Before we go, is there anything that you want people to know about the work that you do that maybe we haven't covered in this conversation?

Lucia: If this is your audience’s first introduction to my work of microbiology and coffee fermentation, and you find this interesting, I have a lot of episodes [of my podcast]—one that I'm really excited about that I did recently is about altitude—this connection of altitude and quality and flavor from a microbiology point of view.

I have three episodes on terroir and that connection to quality and coffee producers. I also do fermentation workshops. I'm hosting them in Guatemala. The next one is sold out—it's coming up in February—but I'm doing more in the future, and it's called Fermentation Training Camp, FTC, and it is open to anybody.

I have 50% set aside for coffee producers and then the rest of the tickets are [for] anybody else who's interested, so we always usually have exporters, importers, we have roasters, we have baristas, and we have just coffee enthusiasts, people who are just really into coffee and want to come spend a week processing coffee with us.

We do three different types of fermentations. And just like meeting other people in the coffee industry. So those are really fun events where for a week you come to Guatemala and we just nerd out about coffee processing.

Let's see if there's anything else podcast, camps…

I am processing coffee right now! I don't have a lot for sale. But I'm working with Tom at Sweet Maria’s to have some small quantities available in the U.S. so that people can try. You don't have to buy a whole bag or 10 bags of coffee to be able to try some of these fermentations that I'm working on. And I think that's it!

Ashley: Thank you so much for joining me.