There are heaps of processes and stages involved in making delicious coffee. We all know this, and I’m not going to beat that dead horse. What I will belabour instead is that every single one of those processes introduces an element of unevenness. I’ve talked about extraction, roast, distribution and blend evenness; but what about everything that happens to a coffee before a roaster or barista gets their hands on it?

Last week I covered how blending coffees can result in uneven extraction and hence uneven flavour. For some, the idea of blending being a source of unevenness wasn’t necessarily a revelation. For others it may have crystallised some suspicions. Here’s a further sobering thought: Every cup of coffee that has ever and will ever be brewed is a blend of sorts. Even single estate micro-lots, you ask? Those too. Everything. And I’m sorry.

Green coffee isn’t really my thing. I’m a Brown Coffee Guy (thanks to James Hoffmann for that title). So to help me understand these farm-level variables I got in touch with someone who knows: Aida Batlle. If you haven’t heard of her, she’s widely regarded as one of the very best coffee producers in the world.

Aida is a GOOD 100 listed, Sprudgie Award-winning, Cup of Excellence Dominating, 5th generation coffee farmer in El Salvador. She’s also super lovely.

Talking with Aida, a few main considerations for evenness at the farm level emerged: variety, altitude, picking, fermentation, drying, sorting and blending. I’ll briefly introduce each from the perspective of evenness, and then I’ll describe how Aida tackles it at her farm, Kilimanjaro.

Aida’s systems and techniques for producing coffee are world-class. She has isolated and removed as many variables as possible to help keep her coffee immaculate. I’d love to delve into all the intricacies, but right now we’re just focusing on evenness!

[In previous posts I’ve mentioned evenness purely in terms of extraction or roast development. Here, evenness is much broader and can affect affect roasting, extraction and general flavour individually or all at once. Although a perfectly even coffee isn’t necessarily the holy grail of quality, I firmly believe it’s an important goal to strive for. The more evenly a coffee is processed, roasted and brewed, the more likely it is to have an honest, focused and unique flavour.]

Keep in mind that Aida’s farms are producing some World-Class Grade-A serious gourmet shit: the vast majority of producers around the world can’t hope to execute every aspect on this level. Please don’t expect it to be standard.

Variety

This one’s huge. The seeds (beans) produced by different varieties can be completely different sizes, shapes and densities. They may also ferment and dry more or less quickly. Variety is one of the the most important aspects for flavour – it also has a massive influence on every other step in the chain.

I’ve tasted many lots of coffee that would have been improved by removing a particular variety from the mix. One recent example: Kenya is famous for it’s SL28 and SL34 varieties. Developed by Scott Laboratories, they were selected mainly for improved flavour and drought resistance. Ruiru 11 is another Kenyan variety, but suffers in the flavour department due to some Robusta heritage. Some Estates in Kenya are planted with both SL and Ruiru varieties, but don’t separate them. This leads to a metallic, dirty flavour that severely reduces the cup score.

Finca Kilimanjaro has two varieties: Kenia and Bourbon. As far as varieties go, these two are very similar. In terms of morphology (physical form) Kenia resembles the SL (Scott Laboratory) strains commonly found in Kenya, which are primarily Bourbon. When separated they also exhibit similar styles of flavour. This means Aida doesn’t have to be too careful about separating them. Kilimanjaro is mostly sold as a combination of both varieties. If a customer requests a single variety or process, the pickers can isolate it for them.

Altitude

Specialty farms are usually pretty high up on the side or tops of mountains. The thing with mountains is that they’re really steep. This means that some farms are growing coffee across hundreds of metres of altitude. Altitude is closely related to the density of a coffee, and I was pretty certain that altitude would have a big part to play in evenness too.

Aida thought so as well, and ran some experiments with the good folks at Counter Culture Coffee to find out. Turns out that a homogenous blend of Kilimanjaro’s beans from 1580-1720m.a.s.l tasted better than the separate lots, and this plays a major part in this farm’s signature taste.

140 metres isn’t a massive spread compared to some coffee farms that span 400+ metres. This leaves me uneasily on the fence considering two possibilities. Maybe Aida is lucky that Kilimanjaro is a fairly “flat” farm that doesn’t experience any noticeable effects of altitude spread. Or, maybe altitude spread could have less influence than anticipated. (If anyone has some data on this I’d love to see it!)

Picking

We’ve all heard of this one. Picking perfectly ripe cherries is paramount. Though, just because it’s common knowledge doesn’t mean it’s common practice. Ripeness and the associated sugar content of the cherry can be directly correlated to cup score. If there is a wide spectrum of ripeness within a lot, you will taste it predominantly through a lack of sweetness.

Aida is absolutely militant about cherry ripeness. If she sees one unripe cherry in the middle of a fermentation tank, someone’s going in there to fish it out. Every cherry is deep red and identical. To achieve this, pickers will make 3-4 passes over the farm and only pick cherries when they’re perfect. I’m also told that with uniform picking, there is little taste difference between each of those passes.

The agronomist who develops a coffee tree that reaches ripeness in unison will be a rich man indeed.

Fermentation

Fermentation is what distinguishes a washed coffee from a dry or semi-dry processed coffee. This is a pretty big difference, and as most roasters will tell you, it has an affect on how the coffee behaves. If portions of a lot are fermented differently, then it’s akin to mixing two processing methods together and hoping for the best: it probably won’t work.

At Kilimanjaro, they separate each day’s picking – or a select portion of the farm from that day – into a single lot. Each lot is then fermented (washed) all together in the same tank. Regularly stirred, it will ferment with excellent homogeneity, virtually eliminating all unevenness from this stage in the process.

Drying

The moisture content of a coffee is super important for how a coffee roasts. Low water activity in a coffee can also retard maillard browning reactions (read: less yummy coffee flavours). This puts drying up there as one of the most important things to get right for evenness. If there’s some dryer and some wetter coffee being roasted together, it’s very unlikely they’ll behave the same way.

Aida uses raised African beds for drying her coffee. This is a great method for evenly dehydrating coffee, and is thought of as the golden standard. Many farms across Latin and South America are now building them to improve coffee quality. She also uses patios, but ensures that there are “heaps of people” constantly raking the coffee around to ensure evenness.

Sorting

Despite all of that effort, a given lot of coffee will contain numerous defects, densities and bean sizes. Sorting is a crucial step towards evenness that cannot be overlooked.

When asked if sorting really makes a difference, Aida gives me a knowing “Ohhhhhhhh yeah. Yeah! It’s massive!”. She says that 15-20% of a coffee will be discarded through sorting (!) and that the increase in quality is completely justified. Machines called density tables throw off lighter and heavier beans, screen sizers eliminate beans that are too big or small and an electronic colour sorter will take a picture of every bean, ejecting anything suspicious. It’s brutal, and totally necessary for evenness.

Blending

When roasters buy a coffee, it’s very often a blend of a few days or weeks of production. Kenyan coffees are typically labelled with the week number while most others are pot luck. A producer may have executed all of those previous steps perfectly, but week-to-week the weather or other variables can change; wreaking havoc on consistency.

Aida keeps every day lot separate and cups them regularly. Even if a coffee ticks all the processing boxes, it can still cup poorly. Frequent cupping allows her to quarantine lots that aren’t performing, and to blend the lots that are. This blending happens at the very last moment before shipping to ensure there are no nasty surprises.

How Is Any of This Relevant to a Barista?

Look out for coffees that are a blend of varieties or a large spread of altitude. I’m not going to say that they are bad – I’ve had many coffees to the contrary – but the fact that there are multiple varieties or large altitude spreads waves a flag. It tells me that there could be noticeable unevenness. This could manifest itself in difficulty roasting, lower cup scores or poor uniformity. It might also, unfortunately, result in a greater perceived complexity. I think it’s important to explain what I mean by this as it’s quite common.

I believe that complexity should be the result of a coffee containing a wondrous combination of flavours and aromas. They should be naturally occurring and greater than the sum of their parts.

Unfortunately, complexity is often used to describe a coffee that has a variety of flavours stemming from unevenness. These flavours might occur because the coffee is roasted unevenly, producing grassy/green and bright/acidic flavours simultaneously. It might be because the coffee contains two contrasting varieties creating roast problems. Or it might just be because a Barista didn’t tamp straight and made a shot that displays both over and under-extraction. These cups will have a lot of flavours that are contrasting and obvious, which leads many a taster to perceive it as complex.

Those flavours aren’t special; they’re not the result of superior growing, processing, roasting or brewing. Because of this, I don’t think they deserve to be called complex.

Please know that I have no problem with someone who enjoys this style of flavour and wants to pursue it. I don’t want to dictate what is best, I want to help you make informed decisions that lead to enjoyment. Understanding the choices made in growing and processing – and accepting that every coffee is some kind of blend – will help you find coffees that satisfy your personal preferences much more easily.

You can find Aida on Instagram and Twitter as @aidabatlle. She posts great stuff from all of her farms and travels (like the ones in this post!)

You can also buy her coffees right now from Square Mile and Stumptown!

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