Let's Talk About Roasting
March 08, 2015
This is a post about how to talk about coffee roasts. It isn’t a post about how to roast coffee (although there's some nuggets in there).
As I was typing up a post about extraction evenness in regards to roasting (which I promise I will get to soon), I realised that the language we use to describe roasting is terribly inconsistent. I was constantly interrupting myself to add notes about why I used particular words and how I believe things work. It was also suffering from diplomacy. So please let me avoid any interruption or tongue-holding and get straight to the point.
[disclaimer] These are my opinions and I have no doubt many coffee professionals will disagree with a lot of it. I’m not trying to be negative or insulting. Please read this how I wrote it; with a neutral, friendly tone that's aiming to help, not hinder.
Roasting is incredibly complex, but there’s 3 main sliding scales that we can use to describe a roast no matter how it went down.
Dark to Light.
Overdeveloped to Underdeveloped.
Baked to Stalled.
Every roast sits somewhere between these 6 extremes. Upon drinking a coffee you can usually identify where it sits on those three scales. Each of them has obvious identifying flavours and make the coffee behave in different ways.
Colour should be easy, but it’s often used to describe all three scales in different combinations. This makes it really hard to understand what someone's on about. Basically, the end temperature of the roast determines colour.
Darker roasts experience higher temperatures in the roaster. They have absorbed more energy which creates more dry-distillates and Maillard reactions. They have minimal acidity and can taste truly terrible (ash, toast, tobacco, burnt toffee etc.). Sometimes, under skilled hands, they’re palatable. Traditionally, darker roasts are assumed to have more body and sweetness. This isn’t true. Dark roasts can be completely lacking in sweetness and mouthfeel.
Lighter roasts experience lower temperatures in the roaster. They have absorbed less energy which preserves more acids and aromatics. They have more acidity and complex aromas (fruity, bright, citric, floral etc.). Traditionally, lighter roasts are assumed to have less body and sweetness. They can, but it’s not just the “lightness” of the roast that’s making this happen. Light roasts can be incredibly sweet and rich.
These sit somewhere between Dark and Light roasts. There are many shades of Brown in here, most of them are some kind of compromise between darker and lighter roasts. Most Specialty Roasters are sitting in here for “espresso” roasts, and a good few for their “filter” or “omni” roasts (omni being applicable for either filter or espresso). I'm looking forward to covering my views on omni roasts in great detail sometime soon.
Here’s where we need to start changing habits. Roasting darker does not automatically make the coffee developed. On the other hand, a light roast is not automatically undeveloped. Don’t make that mistake: development is separate to colour. You cannot see true development on the exterior of a bean. This is because a significant amount of the bean’s interior might still be underdeveloped.
Just before, I mentioned that a dark roast can lack sweetness and that a light roast can be incredibly sweet. This is due to development. With proper development, any reasonable colour of roast can be rich and sweet.
A developed coffee has been roasted in such a way that it doesn’t display any undesirable savoury “organic" flavours (stem, corn, grass, peanut shell, capsaicin, wheat etc.) and its structure has been broken down enough for water to be able to enter and dissolve its flavours (soluble). Developing a coffee perfectly is extremely difficult, and eludes most roasters.
Underdeveloped coffee displays those undesirable “green” flavours and is less soluble..
A vast majority of the coffees I am currently tasting from Specialty Coffee Roasters around the world exhibit underdevelopment. Objectively and subjectively identifiable underdevelopment. It’s a real problem in the industry and has far reaching effects, including:
- reducing efficiency of extractions.
- inhibiting customer acquisition or conversion from traditional “dark roasters”.
- it tastes terrible.
Similar to extraction taints, like dryness or sourness, underdevelopment is a generic flavour. You can get it with high or low quality green coffee. Buying expensive green coffee does not justify or mask underdevelopment. We are “Specialty” - we need our customers to perceive and pay for higher quality - underdevelopment makes that difficult.
Underdeveloped coffees behave in a very particular way:
- If you find yourself grinding one coffee significantly finer than another, even though the colour is similar, that coffee is likely underdeveloped.
- If you struggle to slow down espresso shots with a certain coffee but not others, look to development as the cause.
- If you can’t crack open a roasted bean easily with your fingers, it’s likely underdeveloped
- Break open a bean and look closely at the colour of the outside and inside layers of the bean. If there’s a difference in colour that you can perceive, the inside is definitely underdeveloped.
Roasting darker is one way to reduce underdevelopment, but it’s not the best way. Yes, you will expose the interior of the bean to higher temperatures, reduce the undesirable flavours and increase solubility; but the exterior of the bean is now likely overdeveloped and far too dark. There’s still disparity between the inner and outer layers. The only solution is to apply the right amount of heat at the correct times in the roast to develop the inside and outside of the bean evenly. This allows you to finish the roast darker or lighter without fear of under-developing the interior or overdeveloping the exterior. I say again: with proper development, any reasonable colour of roast can be rich and sweet.
Overdevelopment is when the coffee has become soluble and displays no undesirable organic flavours, but the energy and time applied during roasting has left nothing delicious behind. It’s empty, lifeless and hollow. This is extremely rare, nearly impossible with Kenyan and Colombian coffee, and almost never seen in Specialty. Don’t lose any sleep over it.
At the end of the roast, the coffee beans are quite dry and fragile. Small, brief changes in temperature can make or break the whole roast.
If the coffee experiences an increase in speed somewhere after first crack, that will “bake” the coffee. This is characterised by the coffee exhibiting a lack of sweetness and/or dark roast flavours, even though it might not be a dark roast. You can finish a light roast with a bake that will then taste a little bit bland, ashy or dry. Not ideal. Try not to fall into the trap of calling a baked roast “dark” (it happens all the time and you'll look like a dingus). Look out for dryness, a lack of sweetness, dull acidity, and in worst cases; ash. Sang Ho from Square Mile Coffee Roasters introduced me to calling this the "Flick of Death". Precisely. It kills the party.
If the coffee temperature stops increasing for a significant amount of time, it’s called stalling. Sometimes, the coffee might stall so hard for so long that the temperature starts to drop a few degrees. The worse the stall, the less developed the coffee will be. It’s super hard to pick this one out without seeing a roast profile. If you start calling out roasts for stalling without seeing the profiles be prepared for a slap. Stalling can create weird thinness, waxy cardboard flavours, sharp acidity and sweetness that’s frail and lacklustre.
The coffee can’t experience an increase in speed, and it can’t stop, but it should still be rising in temperature after first crack. At first glance this might seem impossible, but it’s not that hard. Just think of a car constantly slowing down until it reaches a stop sign. Before and during first crack, the coffee should be increasing in temperature quite quickly. This momentum carries it further and hotter after first crack, and allows for a constant slowing until the end. The ideal end of roast is constantly slowing down after first crack until the speed approaches or reaches zero right at the end. This results in no baking and no stalling. If you don’t notice any problems with the coffee, it was likely ideal.
Putting it All Together
So now we have a roast language! This means we can describe any roast accurately and without confusion. Here’s some examples.
"That coffee is light and well developed.” - Hells yeah that sounds great! Bright, sweet, rich and delightful.
“That coffee is dark and underdeveloped.” - Boo. This is the worst of both worlds. Ashy, bitter, no sweetness and savoury green flavours.
“That coffee is light and developed, but baked”. - Ok. So this coffee is bright and light, but also suffers from some dryness or ashiness from the bake at the end.
“That coffee is dark and developed”. - Potentially delicious. Probably not. This coffee could be intensely sweet and rich with minimal acidity and hopefully not too much ash or typical “dark” roast flavours.
“That coffee is a medium roast and underdeveloped”. The most common Specialty roast. It has acidity and is kind of sweet, but isn’t rich, unique or satisfying. It could be a little grassy and savoury, or in milder cases it might just be underwhelming and generic. You might also notice some of the underdevelopment identifiers I described above.
There’s more combinations, but you get the idea. Separate these aspects from each other and we’ll all be able to talk about roasting much more accurately and efficiently!
Please don’t send your coffee roaster an email telling them how much they suck because Barista Hustle said so. Start a dialogue and learn about the aims of your coffee roaster and why they do things the way they do: there’s always a reason! Barista/Roaster relationships are really important and should be nurtured for long term tastiness!
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