Processing, Pt 3 — Critical instruments and poisoned rivers

James: This is Filter Stories. I am James Harper. And this is the Coffee Producer Toolkit, a series made in collaboration with Lucia Solis to help coffee farmers have more profitable businesses. And we've now reached the end of the second episode, on post-harvest processing. If you haven't heard the previous two episodes, I highly recommend you listen to them to get a lot of context, so that what you're going to hear in this episode makes more sense.

As I said at the start, what I'm trying to do with this narration in between these sections is to help you understand coffee farming to a level where you'll know more about it than most professionals you'll meet at a coffee trade show. And I believe this knowledge will change how you see the coffee industry and your journey in it. And with this information, you can mould where our industry goes next.

So coming up next, we talk about instruments. Basically, thermometers and humidity sensors. Now, I should be clear that producers who hear this series will sit across the spectrum. Some will use no instruments whatsoever, and then some will be right at the cutting edge. What we're going to do here is cover the basics and show what is possible at the bleeding edge.

Now, you might be wondering: how is it that producers are not using instruments like thermometers and humidity sensors on the farm? It makes more sense when you understand the context of coffee farming. Before specialty coffee came along, we were in the world of commodity. And in the commodity world, the smartest thing for a producer to do is just figure out what a good post-harvest process looks like on their farm, and then just repeat it over and over. Yes, coffee could be inconsistent season to season, batch to batch, but in the commodity world that doesn't really matter — the coffee was probably going to get blended in with lots of other people's coffee anyway. And so there's no point overcomplicating a process if you get the results you need in budget and you make money.

But that is not the world we're in anymore. To be a successful producer outside of Brazil, you have to differentiate your coffee. A producer has to get premiums somehow. They need a higher price than Brazil, because if they try to compete on price with Brazil, it's not going to work. And so they can go down the specialty path to get higher premiums. But specialty requires a lot of care, a lot of attention, a lot of consistency in the process to get reproducible, high quality flavours. And to achieve that, producers must use instruments like thermometers.

Producers who have been very specialty-focused for a long time already use lots of instruments. But for producers who are getting into it, this is a learning curve. Lucia and I want to help them on this learning curve. We want to help them get to grips with what kind of instruments they need to produce more consistent, higher quality coffees.

Now, one other thing. You're going to hear towards the end of this piece Lucia talking about arefractometer. A refractometer is a tool that was borrowed straight from the wine world. In wine, you take a grape, you squeeze some juice into the refractometer, and it tells you the sugar percentage in that juice. This is technically known as a Brix reading, B-R-I-X.

Okay, pressing play.

James: Now, let's talk about instruments. Because to measure and track your post-harvest processing, to produce coffee reliably, consistently, year after year, batch after batch — you can only get that with good instruments.

Lucia: That's right, James. And from my experience, I don't think producers take advantage of enough instruments.

James: I have a story of what happens when you don't use the right instruments. So, when I was in Colombia, we spoke with Victor Chala.

Victor Chala: Good evening. My name is Victor Chala. The name of the farm is called Palma Rosa.

James: Victor named his farm after a tree, the palma rosa. He has about 18,000 coffee trees. Victor works very closely with The Coffee Quest, who have a buying station in the town of Santa Maria, a 40 to 50 minute drive away.

Victor Chala: We were in about 40 minutes, 50 minutes in car.

James: One day, Victor brought down a large delivery to the buying station: 160 sacks, 8,500 kilos of parchment. But when that coffee was checked, most of it had too much moisture, and it was not accepted.

Victor Chala: Y me salieron como 130 bultos de café en humedad 12, de 12, 12.5.

James: The Coffee Quest only accepts coffee at 11% moisture. His was at 12, 12.5%. Transporting coffee is very expensive, so it didn't make sense for him to bring it back to the farm. And so for the next three days, he spent all his time down at the buying station, drying his coffee on the street.

Victor Chala: Y usted se imagina, uno con toda esa cantidad de café para poderlo templar, darle un secado en las calles...

James: And to make things worse, it kept raining, which meant constantly gathering everything up, waiting for the rain to pass, and then spreading it all back out again. It took three days of his life to nurse that coffee down from 12% to 11% moisture.

Lucia: Three days drying coffee on the street outside the buying station. It's what we were talking about earlier, where that last bit of moisture is really stubborn and doesn't want to go. That's a pretty expensive lesson. That's three days he could have spent on his farm, managing his other lots, managing his pickers. That is time robbed.

James: Now, this unfortunately happened to Victor because he didn't have the right instruments. Up until that point, he had been doing what actually most coffee producers do, which is use the bite test on his parchment.

Lucia: And the bite test is exactly what it sounds like. Essentially you take a seed and you bite into it. And when you're biting into it, if that seed is still soft, then it obviously still has a lot of water, and it's not going to be ready to pick up and put in the warehouse. [unclear] And I've been really impressed to match, you know, their skills to the instruments.

James: And I should say, Victor himself is extremely experienced. He's been in coffee for decades. But he admitted that on this occasion he was so busy that the bite test failed him.

Victor Chala: No, yo... el diente no, el diente falla.

James: And so this experience led him to buy a moisture meter.

Lucia: Let's see it. A grain moisture tester, the PM450.

James: But Lucia, this is not cheap. A thousand dollars.

Lucia: Yeah, typical moisture meters are expensive. The meters include a scale anda thermometer, so you weigh out a specific quantity of coffee and the device can compensate for different coffee temperatures, because that impacts the reading. Then they estimate moisture by sending a small electrical signal across the sample, and depending on how much water is in that sample, the electrical signal will encounter more or less resistance. The device then takes that resistance reading, the weight and the temperature, and uses an internal algorithm and a calibrated curve specific to coffee to give a moisture percentage.

James: Right, so this is a very sophisticated instrument. And, of course, it has a very hefty price tag attached.

Victor Chala: Es costoso, si, es costoso. Pero cuando ya lo tenemos en la finca y nos damos cuenta de la necesidad que es para nosotros, es una herramienta de trabajo para nosotros.

James: There is good news though. You don't need to invest in an expensive moisture meter — there are cheaper alternatives.

Lucia: We can use a very low-tech option, which is just weight. We know how much coffee there is, and by weighing the coffee you can see how much of it is the material of the coffee and how much is water. So if your coffee is losing weight, it's losing water. Something as simple as a scale and a set volume, without having to spend several thousand dollars on an official instrument.

James: And you can actually buy moisture meters that work this way. For example, there's one sold by Innovakit, which we have linked in the show notes — basically just a basket on a scale. And you could also make your own, of course. Now, let's look at other instruments you need to measure and control the drying process.

Lucia: So, in addition to that moisture meter, you need thermometers and humidity sensors in your drying tunnels and your patios. You want to measure how fast the coffee is drying. And to get this information, I recommend three types of thermometer.

I like to use the metal kind that has a probe, so that you can stick it into the coffee mass and get a more accurate measurement of the coffee itself. I like to use the temperature guns that get the surface temperature — you know, I think we all got used to those guns during COVID. And then temperature and humidity meters for the room.

James: And also, to add: we haven't covered fermentation in this episode, but you will also need thermometers for tracking that as well, as well as other things we'll cover in the next episode on fermentation.

Now, of course, what really matters is what you do with the data. You can take all the readings in the world, but without a system to act on them, the data doesn't mean anything. And to give you a sense of how far you can take this, one of the agronomists we spoke to in the previous episode, Manuel Mata, from the Santa Marta region of Colombia, walked us through this remarkably sophisticated setup.

Manuel Mata: Puedes ponerlos en un tanque de fermentación o donde estás secando el café. Y ellos, cada 20 segundos, te están registrando muchas variables. Por ejemplo, temperatura, humedad relativa.

James: He's built this system of digital temperature and humidity sensors, the kind that cost $40 to $50 each, that take readings every 20 seconds.

Lucia: Wow, he's really taken sensor-based monitoring about as far as I've seen on any farm. He's next level, for sure.

James: Yeah, and Manuel uses sensors as an early warning system, alerting him the moment something drifts outside of the recommended range.

Manuel Mata: Automáticamente te dé como una advertencia cuando te estás saliendo de esos rangos.

James: Right. So, for example, during fermentation he has these sensors inside the barrels, transmitting readings directly to his phone. So let's say one of his workers makes a mistake and leaves one of the fermentation barrels in direct sunlight.

Manuel Mata: Entonces, el sensor me advierte. Entonces, yo tengo que llamar y preguntarle qué esta pasando.

James: He would get an alert on his phone saying the temperature inside the fermentation barrel is climbing towards 30 degrees Celsius — it's too hot. He'd get that alert on his phone, call his team, and then they move the barrel into the shade.

Lucia: And this is the critical lesson. You can collect a lot of data, but that data only has value if you're using it in real time.

James: Now, Manuel is somewhat of a technical person, but he does insist that building a system like this is simpler than it looks.

Manuel Mata: Actualmente no es complicado conseguirlo. Y lo que ayudan es un montón.

James: Okay, so before we wrap up this section on instruments for post-harvest processing — Lucia, there's actually an instrument that you recommend producers don't use for the harvest.

Lucia: That's right, James. I think producers should stop using refractometers.

James: To be clear, this is specifically for the harvest. Refractometers have a lot of value for controlling fermentations. But why shouldn't producers also use this tool that they already have for the harvest?

Lucia: Well, it's true, a refractometer can be useful. But most of the time, most Brix readings — that's, you know, for wine, to measure the fruit — part of this is to measure sweetness, or what they think is that they're measuring sweetness. And because of this, you're seeking high numbers, you're seeking a high Brix, because people are equating that to a high amount of sugar, a high amount of sweetness in their coffee. But the data hasn't supported this relationship. It hasn't supported the relationship that high Brix cherries equal high sweetness coffee. There are simply too many steps between harvesting cherries and the final cup preparation for Brix to translate to anything, for Brix to really give us any information at all.

James: Right. So don't use a refractometer to measure the sweetness, the ripeness, of your coffee cherry.

Lucia: Yeah. And actually, there's a second problem in addition to this first problem. [unclear] It would relate to people thinking, oh, I have a lot of sweetness, that's a positive thing. But what you're actually showing is that the cherry can be dehydrated, because Brix is a concentration.

James: Right — because if a cherry dehydrates, there's less water, therefore the sugar percentage goes up.

Lucia: That's right. If your sugar is increasing because the plant is producing more carbohydrates, that's great. But if it's increasing because your plant is losing water, that is a serious problem. The refractometer can't distinguish between those two.

James: Got it. So instead of a refractometer, what do you recommend producers use to assess the ripeness of their coffee cherries?

Lucia: I actually recommend here not using tools, but going back to the old-fashioned approach and using our senses. Use your eyes to look at the colour of the cherry. Use your hands — feel whether the cherries are soft enough to pulp cleanly. That's pretty much it.

And then, during the cherry picking itself, I recommend using a cherry classifier. It's a simple device that you can buy or make yourself by taking a plank of wood and drilling out a grid of 10 holes down and 10 holes across, to get a hundred holes that will fit a coffee cherry. When your coffee arrives at the mill, you take a sample of your cherries and you use this device to sort by colour and ripeness. This device gives you a way to see the quality and the percentage breakdown of green versus ripe versus overripe cherries. And then that gives you a number that you can track over time to see how your harvest is progressing, and it'll give you valuable data for your future fermentations.

James: And would you believe it, Innovakit also sells one of those too.

Lucia: I think you need tools. Even simple tools like a cherry classifier can make a difference. These tools allow you to track what you're already doing and make sure it's being done carefully and consistently. Catching your fermentation before it goes wrong — that saves money. Knowing your coffee is dry enough before you load it onto a truck — that could save you three days of your life. These are the moments where small investments in equipment and tools pay for themselves many times over.

Building a solid system will lead to consistency, which means you can create quality coffee day after day, year after year. This type of consistency is what builds buyer relationships. And ultimately, that's what puts more money in your pocket.

James: Okay, and coming up next, the final section of this episode: how to manage your wastewater.

James: Pressing pause. In this final section, we talk about wastewater, and it is one of the coffee industry's dirty little secrets.

Traditionally, wet mills have used a lot of water. They use a lot of water to wash off all the sugary fruit from around the coffee seed, and water for the fermentation. And what you have is this water that is just extremely full of sugars and pectins from the mucilage. And in the past, this was all dumped in the local river. And it was a disaster, because bacteria would gorge on the sugars and the pectins, and as they multiplied, they would suck all the dissolved oxygen out of the water. And this would suffocate everything. The fish would die. The invertebrate life on the riverbed, and frogs, wiped out.

And what makes it all worse was the timing, because the harvest is concentrated into a couple of months, and that would often fall in the dry season. And so all this sugary mucilage would be discharged into the river at precisely the moment when there's the least amount of fresh water to dilute it. And if people lived along that river and depended on it, they could no longer drink it. They could no longer wash in it. They could no longer fish in it. And this has hit indigenous communities especially hard.

Now, these are the horror stories, mostly of the past. You still find some cases today where it happens, but it's quite rare. More often today, what happens is that when you visit a coffee farm, you might find beautiful facilities, spotless patios, gleaming fermentation tanks. But then you walk around the back of the wet mill, and there's just a concrete tank sunk into the ground, overflowing with dirty water. This water is not being treated properly, and oftentimes it overflows: new wastewater comes in from the processing and it just displaces the old water, which spills out over the edge, still contaminated, still carrying way too much sugar and pectins, and it just runs off down into the surrounding environment, and down into the local river.

Lucia and I felt it was too important to ignore. We had to tackle this head-on in this series. We both care about the environment, so of course this matters. But also, it matters commercially. A lot of coffee buyers are waking up to this — coffee buyers really care about a coffee farm's environmental credentials. And for certain certifications, how you handle your wastewater does matter as well.

So we wanted to end this episode by bringing this all to light. And this is the end of the postharvest processing episode. I'm just going to let it play out from here. I hope you've enjoyed these three parts on post-harvest processing, and that my narration has been helpful, and I will speak to you in the next episode. Pressing play.

James: So Lucia, when it comes to post-harvest processing, oftentimes some water, or a lot of water, has to be used.

Lucia: Yes. And the problem is all of that water has been used now and is contaminated to some degree.

James: How bad have you seen it?

Lucia: The mill next to my farm used to discharge directly into the river. This was very much: pull water from the river, use it to process and ferment coffee, and then put it back into the river. And so today, I live near one of the most polluted rivers in Latin America. It's called the Guacalate. And it is so sad to see this body of water that is just grey and incredibly toxic being used — and, you know, further downstream, for a lot of indigenous communities that is their source for their bathing water and drinking water and usable water. So it is very important to take that responsibility seriously.

James: And also these days, look, treating your wastewater really matters for your farm. For a start, buyers are beginning to ask about how your water is treated. And many certifications also require you to treat your water carefully. Treating your wastewater is not a nice-to-have anymore. It is essential.

But Lucia, I could also imagine many producers listening to this right now are saying to themselves: oh, I don't need to worry about this, because my wastewater management is great. You know, next to my mill I have a tank that collects my wastewater. I'm fine.

Lucia: Yeah, I know, James. [unclear] Where the tanks are not well maintained — and if they're not, the water isn't getting the treatment needed before it can re-enter the water supply.

James: So the first step in tackling this water problem is actually to reduce how much water you need in the first place. Now, we've already covered a lot of that ground in this episode. We spoke about vertical pulping systems that require a lot less water. We heard from David in El Salvador, who uses a lot of Pinhalense equipment in his wet mill with elevators — that's cut his water use down from three tanks to one. And you can also reduce how much water you need during fermentations, and we will cover that in the next episode as well.

Lucia: Right. So the important step, as you're saying, is to use as little water as you can. And the second step is to treat what's left.

James: And so now we want to share with you two examples of post-harvest water treatment: a simpler one and a more complex one, to give you inspiration on what a grey water system can look like. The first is Melissa de Gasperin in Cordoba, Mexico. We heard from her earlier.

Melissa de Gasperin: Lei teoria sobre la limpieza de agua a través de filtros de piedra, de arena y de plantas.

James: Hers is the simpler system, where the wastewater from processing is collected in a tank, and that's where the organic matter begins to break down. And then it flows into this artificial wetland, where she has layers of gravel, volcanic rock, sand and vetiver grass that act as a natural filter, cleaning the water over about seven days. From there, it then passes through a mechanical strainer to remove remaining solids. And then Melissa also plans to add a biodigester, which will further reduce the organic load before the water is released back into the surrounding land. But what's really nice about her system is that most of the water actually just evaporates out of the wetland. That's how she gets rid of it.

Melissa de Gasperin: Si, ahorita se evapora realmente.

Lucia: This artificial wetland is a really beautiful approach. I really like it because it's both low-tech and low-cost. And then you are relying on the plants and microbes to do this biological breakdown, to do the filtration.

James: But you could take this much, much further.

César Marin: Bueno, mi nombre es César. Nosotros somos productores de café en Perú.

James: We spoke with César Marin. His family farm, Chacra D'Dago, is a pioneer in biodynamic coffee in Peru, and his water treatment system is really sophisticated.

César Marin: Todas esas aguas las mandamos a tanques de tratamiento donde...

James: So, once the wastewater reaches his treatment tanks, he uses minerals to separate the solids from the liquids. The solids, which carry most of the sugar and the organic matter, are pumped to a separate area where he adjusts the pH before adding them to compost. The water, which is now free of solids but still not clean, goes into filtration ponds planted with aquatic vegetation that capture the remaining carbon. And then he adds minerals and activated charcoal to further purify the water before it's released into nearby streams.

César Marin: Para que luego el agua vaya lo mas limpia posible al recurso hidrico mas cercano.

Lucia: What I really admire in César's system is that he's not doing this because of external motivations, like government legislation or to avoid a fine. He's doing it because he knows the benefits to himself and the community. He knows it's important for the longevity and sustainability of his business.

James: So to wrap up: reducing the amount of water you use and then treating your wastewater isn't just good environmental practice. We are in an era of climate change, of unpredictable rainfall. Using less water future-proofs your farm. You need to prepare your farm today for an era where you're going to get a lot less rainfall, where you're not going to have as much water available for post-harvest processing. So get this right now. Use less water now.

But most importantly, when you get this right, it becomes a story you can tell your buyers. Buyers want to be able to tell their customers how the farms they work with are treating the environment. And if you can show that you are treating your water to this excellent standard, it puts you in a stronger position to negotiate better prices. And that ultimately leads to a much more profitable coffee farm.

Lucia: All right. Let's quickly recap the things we want producers to walk away with from this episode.

James: First: don't experiment with risky processing just yet. Get your fundamentals consistent before you even think about getting a bioreactor. Can you make the same coffee, with the same process, 10 times in a row? Nail that first. And then chase efficiencies.

Lucia: Second is picking. Harvesting cherries is a major cost. Simple, low-cost tools can dramatically speed it up. Push past the resistance.

James: Third: float your cherries. And float them before you pulp them. And if you can, get a coffee cherry sorter.

Lucia: Fourth: stop chasing 100% red ripe cherries. Aim instead for an 80/20 ratio. Chasing that last 20% is costly, and honestly, I think your coffee is [unclear].

James: Fifth: pulping. Go vertical. Let gravity move your coffee, not water.

Lucia: Sixth: drying. Keep the coffee seed below 40 Celsius. And if you want to dry faster and you have a mechanical dryer, use it at the start of drying, when the water is still protecting the seed — not at the end to finish coffees off, because that's when the most damage can occur.

James: Seventh: buy the best moisture meter you can afford. Get thermometers. Get humidity sensors.

Lucia: And remember, data only has value if you use it.

James: And finally, water. Use as little of it as you can, and then treat what's left to a very high standard.

James: So, thank you for listening. In the next episode of the Coffee Producer Toolkit, we tackle fermentation.

Lucia: I can't wait for this one, I'm so excited.

James: If you found this podcast helpful, please share it. This is an independent project by two people trying to do their best, and we're really relying on you to get the word out.

We've also covered a lot of these topics on our respective podcasts.

Lucia: Right. And if you want to go deeper into drying specifically — why the seed cares so much about how you dry it — I have two episodes on my podcast. There's the one I mentioned earlier in this episode. And episode 71 is much more practical: it's how to get your naturals to dry faster without any funky flavours.

James: And on my podcast, Filter Stories, I made a documentary about a Colombian producer who could produce specialty, but he doesn't, because he sees that the extra work required just isn't worth it — he's better off using his time in other ways. All this to say, specialty is not a panacea, and I show you why that's the case.

Lucia: We're both on Instagram, at Filter Stories Podcast and at Lucia Solis.

James: And the best way to stay in touch with us is to sign up to our newsletters. We've got links in the show notes.

Lucia: This series of the Coffee Producer Toolkit was produced by myself, Lucia Solis, Nick Hafner and James Harper. James also wrote and played the piano music.

James: Thank you for listening. We'll speak to you next time.

Lucia: Gracias por su tiempo y hablamos en el próximo episodio.