Fundamentals: Roasting Dry Process Coffee

A short guide to navigating the challenges of roasting dry process coffees

by Christopher Schooley

Dry processed coffees are becoming fruitier and fruitier. This is mostly because there is a lot more sorting of cherry going on these days in this processing method, both by hand and with equipment designed to wash and sort the cherry before drying on patios or raised beds. As a result, the traditional rustic and earthy flavored dry processed coffees are giving way to cleaner and brighter fruits. Even in the dry processed coffees of Brazil, there is more and more sorting being done. Yes, many Fazendas still mechanically strip-pick the coffees, but there is intensive sorting going on there as well, and there are more producers working towards more selective picking.

The more earthy and rustic characteristics of the traditional dry processed (DP) coffees required roasting that helped to bring out the sweetness, pushing the sugar caramelization more into where there were more bittersweet cocoa notes. In lighter roasts these coffees were rough and gritty, with so much texture in them they seemed downright chewy!

"Instant test roasting" - They call it that, but what they are doing is drying humid parchment coffee in one Probat, then immediately hulling it and then roasting it. Rantepao coffee buying station, Toraja, Sulawesi Sulawesi
Roasting small batches of coffee in a Probat four barrel sample roaster.

These coffees needed roasting that took the edge off of the earthiness. We would us longer drying times and stretched 1st Cracks to achieve favorable results, often roasting into the darker Full City neighborhood in order to bring out the cocoa roast tones, and round off the rustic edges.

This approach to roasting has a lot to do with the mixed density of the beans. In the traditional dry processing method there is a layer of sorting and separation that is missing and which results in the green coffee having a wide variation in density, bean size, and even ripeness. Depending on the initial quality of the coffee, sorting it can result in a cleaner cup. On the other hand, you could lose some of the complexity and characteristics of the coffee that you enjoyed in the first place. One thing’s for sure, sorting requires extra labor and machinery, and so the level to which a coffee is sorted must line up with an improved cup, and ultimately, a financial return.

I say “has as lot to do with the mixed density” because even though there is better sorting for defects which add more of the unpleasant characteristics to the cup, the end result still is pretty mixy density wise. This is noticeable when roast dry process coffees by the way they seem to drag their way into the fracturing stage, and then 1st Crack doesn’t seem to ever stop (until 2nd cracks, of course!).

The reason for this is that the lighter density coffee cracks first, and generally has a more muted ‘snap’ to it, and then the more dense coffee doesn’t start cracking until most of the charge has already finished popping. Not only is the first crack offset because of the mixed bean density making it a little tricky to track development, but the lagging 1st Crack can add to the lack of cup clarity, particularly with the more fruited notes.

Burundi doesn't always have the best climate for making natural coffee, simply drying the cherry as it comes from the tree. I feel naturals need to dry within 14 days or so, then have plenty of rest time afterward to stabilize. If they dry too slow or in wet weather, the taste can go south. This is at Mubuga station. Didier is manager. 300 tables. 400 tons is target. 1580 meters.
Dry process coffee cherry on raised beds of chicken wire and mesh to allow for airflow, and even drying – Burundi.

One fix to this issue is simply to push a little harder into the 1st Crack just before it starts. At around 365F degrees (depending on your roaster model – but generally 25-30F before 1st C), change the air flow or energy input in a way to put more energy on the coffee in order to get more of the charge popping at the same time. If you were to look at an XY axis roast diagram, in most cases you’d see a slight decrease in the rate of rise right at this point as the beans absorb the energy on the verge of 1st Crack.

It’s important to note that you have to be careful with coffees grown at low elevations, that are generally already low density. Dry process Brazils, for example, can really take off at this point if you don’t pull back on the energy input soon enough once the 1st Crack is rolling.

I still prefer pulling back on the energy input with dry process Ethiopias once the 1st Crack is rolling, but it is vital that you don’t pull back too early. One of the most common mistakes made with DP coffees is pulling back much too early once the 1st Crack is engaged. This tends to stall out the 1st Crack, or at least drag it out, rounding off much of the vibrance, leaving the fruit seeming limp.

Double pass naturals ready to be pulped, Brazil coffee re-soaked in water
Whole coffee cherry is rinsed at this Brazilian coffee farm before drying. You can see the unripe coffee mixed in (green and yellow color), which add to density variance.

If you’re trying to get that fruit to pop, you want a condensed and boisterous 1st Crack. The pops themselves tend to be a little quieter in dry process coffees because of density and moisture variance, but you should still be able to get a boisterous 1st Crack if you’re able to get the majority of the beans popping together. There may still be a few stragglers but not nearly as many if you weren’t to push the head leading into 1st Crack. Dropping the roast just 15 – 30 seconds after the end of the 1st Crack will get you that really snappy tart fruit. Roasting darker from this point will develop more of the roast bittersweetness.

Another approach to roasting dry process coffees in a way that highlights both fruited notes AND a sweeter cocoa finish (rather than just the snappy tartness of the fruit turning more towards sharp bitterness) is to stretch out the drying stage. This is a pretty great approach in general when working with rustic coffees, but even in cleaner dry process coffees, this approach is really helpful in being able to work towards a sweeter finish. A longer drying phase allows for more of an equilibrium between the mixed density before any browning occurs, which makes building to a unison 1st Crack a lot easier. You can still push into 1st Crack at this point, but you shouldn’t need to push as hard. Just make sure it’s a solid boisterous 1st Crack!

I never like to extend the 1st Crack itself because I feel like it just tends to flatten the cup and you really are flirting with baking and stalling caramelization doing this. You can add 15-30 seconds to the 1st Crack at this point to try to add a little more texture to the mouthfeel, but extending it towards a full minute or more is not recommended! I prefer keeping my 1st Crack time to around 2:00. With an extended drying phase, it may take some of the punch out of the fruit, but will likely lead to a sweeter, longer finish.

Check out our Coffee Class: First Crack, Second Crack, Coffee Roasting Development

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