Lightness and Darkness in Roasting

Roasting coffee is, put kindly, a fickle affair. On a good day it feels like chasing a dropped piece of paper in the wind. On a bad day it feels both impossible and unknowable.

In recent years roast degree has become imbued with a kind of morality. A tenet of modern coffee is transparency, and we know that any step in the seed to cup process can cloud it or leave it clarified. Roasting, of course, is perhaps the most obvious step for scrutiny. Roasting a coffee to a deeper degree obscures its origins, any taste of place smothered under generic, carbon-like roast notes. This was considered bad, because this practice works well should your taste of place not taste very good. Low quality coffee would obviously be roasted darker to hide its shame. 1 Starbucks were long held up as the evil doers in the world of dark roasting. The reasons proffered within the community were many and varied: “They do it because they buy bad coffee.” or “They do it so their coffee tastes the same all over the world.” or “They do it so it is easier to extract/it’s more tolerant.”. Now is to the time to examine or debunk these claims, perhaps another time… Continue reading “Lightness and Darkness in Roasting”

  1. Let’s avoid the substantial contrary evidence of instant coffee and rapid roasting, where the coffee is roasted very quickly and dropped quite early. This has the dual benefit of leaving more soluble material and not causing problems – like fires, that rapid roasting to second crack will inevitably cause.  ↩︎

Explanation of yesterday’s graph

So yesterday I posted up a little graph to see if people could identify it.  It was a tricky one, and I was pleased when Kevin Cuddeback, CEO of Gimme! Coffee, chimed in with the correct answer.  What the graph represents is the rate of increase of temperature in the bean mass (calculated to be per minute) measured every 30 seconds in a roast.  I removed the first part because formatting a graph to look nice when you’ve got to drop to -100 on your x-axis is difficult.  Plus, it would have made things too easy!

Here is the graph again, properly labelled:

I posted this for a couple of reasons:  Primarily I thought it was interesting.  Secondly I wondered if other people were looking at roast data like this.  I’ve only produced a few of these curves, as I have to do it manually at the moment, and they are confusing to read.  Bear in mind – if the graph were to flatten out it would simply mean that the bean mass is increasing in temperature at a steady rate.  The roast curve would be point up, it would just be straighter.

Other roasts have produced extremely different profiles.  I need to get more data and start doing comparisons!

This is also interesting because there are changes in the rate of the bean mass absorbing heat that don’t correlate to changes in gas or airflow.  I don’t know whether evaporative cooling has much impact on rate, or why we don’t see a faster uptake of heat once the coffee is dry.  The curve on this roast between 6 and 8 minutes is particularly interesting to me.

I should note that this was a test, rather than production roast.  It was dropped not far past 1st crack, as you may surmise from the graph.  We have a colour meter but it doesn’t produce accurate Agtron numbers.  It cupped pretty well, but was out-cupped by a slightly different profile that I don’t have this kind of data for.  (Annoyingly)

Anyway – I thought it was interesting, and I hope it might generate some discussion – because we are really bad at openly discussing roasting theory online.

Why I’m not a roaster

Whoever is doing the PR work for the position of production roaster deserves a bonus. I can’t think of another position that is as widely coveted within our industry. Roasting seems so creative, so romantic, so artful. We talk about hand roasting, or small batch roasting, or emphasise the craft of it all the time. Roasting is often seen as the pinnacle of the coffee industry, or certainly up there with being a buyer.

Personally I would think an accurate description of coffee roasting would be food manufacture.

Whether you see the roasting process as being transformational and an act of creation, or you see it a necessary step that shouldn’t hinder the transparency of the raw materials qualities – what makes a great production roaster is the ability to pay attention to detail, to be focused, and to do exactly the same thing time after time after time. A great roaster should be working to replicate a desired roast curve, and only deviate once feedback from the cupping table prompts a change. Consistency, not creativity, is at the root of the job description. Yes, there is cupping – lots of it. This is also a time when people basically look for flaws in what you’ve done (as well as commend great roasts). Roasting is hard on the ego if you’ve got a great group of cuppers giving you feedback.  Roasting the same coffees over and over doesn’t offer some immediate insight into coffee generally.  You still need to taste many different coffees, cup a lot and brew a lot.

I’ve roasted enough to know that I am not a great roaster. I certainly wouldn’t hire me to roast coffee for a living. 1 I don’t have the attention span, the strength of mind. I have lots of stupid ideas for experiments, and in production you can’t whimsically mess around with a roast and then pass along experiments, that may well be awful, without warning to and consent from the customer first.  Don’t get me wrong – I’m extremely interested in roasting, I want to understand the process, I want to better connect a roast curve to a cupping bowl.  I’ve spent a lot of time reading about the chemistry, and I enjoy discussions with other roasters very much.  This isn’t enough to make me good at it for a living.

This isn’t me saying I don’t believe in experimentation – but this should have its own budget and time set aside, and shouldn’t be incorporated into production schedules.

Thankfully I work with people who are great at production roasting, and I hope they enjoy what they do.  (They also have the patience to put up with my sideline dabbling/ temper my attempts at backseat roasting!)  If you know what you are in for then I think roasting can be extremely satisfying.  The best thing is that you make things: At the end of the day there are shelves full of bags and boxes of stuff that you helped make – the creation of a physical product is so wonderfully pleasing and no empty inbox or spreadsheet can compare with that satisfaction.

I think we need to be more honest at what roles entail, and what they’re like to work. It doesn’t work for employer or employee to find out after 3 months that a role doesn’t work. Time, effort, training, money are expended and it is back to square one for everyone. When the right person finds the right role then you have lasting job satisfaction, and the company and the individual flourish.

I should probably add that production roaster can mean many things – with different levels of responsibility and opportunity to provide input into how the coffee is to be roasted.

If you want to be a roaster – then maybe see if you can just hang out with a roaster who is hiring for a couple of days. Do what they do. Get some genuine insight into that process. This is also one of the reasons I think a lot of people transition to roasting from another role in the same company – chances are they have a pretty good idea of exactly what is involved.

Also – learn to like lifting heavy things…

If anyone reading this happens to be a production roaster – I’d love to hear your thoughts?

  1. You may ask – if I have nothing to do with production – exactly what is it that I do at work all day….  ↩︎

The future of speciality coffee

It was hard to listen to the various presentations at the SCAA Symposium this year without thinking about what it would mean in real terms for quality coffee in the future.
I don’t profess to make particularly accurate predictions (the various annual efforts on here stand as testament to that). However, based on the various talks I would make the following guesses:

A shift in production away from diversity

Currently about 60% of the world’s coffee comes from just 4 different producing countries. I hadn’t realise the distribution was stacked that way, but these are countries that are able to apply new technologies relatively easily that will allow even greater yields without expanding the area given up to grow coffee.

My prediction (in between 10 and 20 years) would be that 60% from 4 becomes 80% from those 4 countries. Right now there is a lot of incentive to grow coffee in Brazil. Not only are prices high but exchange rates make their currency even more valuable. This will spur greater investment and a significant bump in yield. The majority of this coffee will be poor to average. Variety/genetic research will focus on palatability of product, rather than excellence.

Coffee is chased up the mountain

Climate change means that coffee growing at current altitudes will be decreasingly possible and rewarding. Farmers at lower altitudes will likely switch crop to something more stable and less affected by disease and temperature (palm oil etc). Those that can grow coffee higher up, where temperatures remain cooler, will continue to do so. However, this reduction in planted area for coffee (as well as a hopeful focus on quality in order to make a sustainable living) will make coffee grown at altitude increasingly expensive.

Climate change figures (esp likely temp changes) seemed to vary at Symposium, but I hope Dr Peter Baker’s presentation will be made available as it was both informative and compelling. No one seems to be arguing the base fact that less land will be viable for speciality coffee in the future.

Diversity in speciality coffee

Throughout Central America, some of South America and East Africa I expect to see less total coffee being produced – especially less speciality coffee. This will drive up prices further but I think we’ll see some truly exceptional stuff as we learn more about producing higher cup quality on purpose. (Looking to the GCQRI on that one….)

If you retail coffee then start thinking about how you’ll see it when it doubles in price. I think it will, and will be sustainable there too. The gap between speciality and commodity will widen significantly. I think genuine speciality (some would say high-end speciality) will also break away from the broad church that we cover with the term “speciality coffee” today.


We’re going to see GMOs in coffee. I don’t like it, you probably don’t like it, nobody wants to talk about it, but I think these will likely appear first in the big 4 producing countries where there is greater need for economic stability from the coffee trade.

I hope that speciality works contrary to this to start to mine the genetic diversity in nature to see if we can’t find what we need there.

In summary

I don’t think fantastic coffee is going to disappear despite the challenges it faces. It is going to become increasingly scarce and its cost of production on top means that we’ll see a much bigger divide between C-market (which will likely drop back) and Speciality. You’ll have to fight to find it and buy it.

Whether you can plan that far ahead about how to be effective in a market that different, I don’t know. It is certainly worth some thought.

I’d be interested to hear from anyone else who was at Symposium, or who is interested in this sort of thing, about how wrong they think I am!

Sugars in roasted coffee – a conversation

I’m posting this (with consent of the other conversants) in an effort to kickstart some more open discussion about roasting. Right now there is very little out there when it comes to roasting speciality coffee. I am aware that most of the studies quoted below were probably done on C-grade coffees.

I hope we can get to a place where we can discuss profiling, roast development, densities and the like with a view to understanding what we do better and to reduce the time we put into trial and error profiling. Undoubtedly lots of great roasters aren’t just heating and hoping – they are applying a lot of what they’ve gained from previous experience and other knowledge. Continue reading “Sugars in roasted coffee – a conversation”

A grand unified theory of espresso

Not too long ago I posted on Home Barista about trying to find a good way to measure the density of coffee beans.  1

As always the paricipants there were way smarter than me and offered several interesting options. I dropped into the thread that this was part of my idea of a grand unified theory of espresso, and subsequently a few people mailed and pm’d me asking what on earth I was talking about and what density had to do with it.

Well, I should probably explain what I have been thinking.  2

Continue reading “A grand unified theory of espresso”

  1. There really is no better place on the web for these kinds of questions!  ↩︎
  2. Some of this is based on personal preference, some on what seems to be fairly well agreed upon within the community of people who worry a lot about their espresso.  ↩︎


Stumptown are the source of one of my most troubling coffee experiences, one that still haunts and nags at me today.

No one in the coffee industry really likes decaf.  We excuse its taste, we get annoyed at how fast it stales, we treat it as a second rate coffee experience.  I was in that camp too for a while.  Coffee no good?  Well, it is decaf…..

Continue reading “Decaf”

Thoughts on the last Esmeralda auction

According to the owner of the stoneworks auction website, I was one of up to 3000 users watching or participating in the latest auction. It went on for 9 hours and you had to feel very, very sorry for the Japanese who would have started bidding at 10pm and finished around 7am. (though you suspect they probably had access to sufficient caffeine)

I am not going to go through who won what (it is there on the website still) but there are a couple of things about this auction process, about the success of this farm, that I want to write a little about and get some feedback on from the community.

First of all I was quite surprised that the Petersons decided to auction off so many small individual lots. The high prices achieved in the past were a function (in my mind) of both quality and scarcity. I don’t debate the mesmerising cup this coffee is capable of producing, but I don’t think that it would have reached $130/lb last year if there had been 10 times the volume available. Granted, the small individually processed batches have drive the price up on the top lots to similar heights but this then leaves the issue of how to communicate the difference between Stumptown and Sweet Maria’s $105.25 lot and a $6 lot. What key areas would the consumer respond to and be willing to massively increase their spend for?

The variation in price also implies a variation in quality. This is not a criticism of the farm – no farmer in the world is going to claim they produce nothing but exceptional coffee. I do worry, however, that there is potential to damage the brand. (and I have no doubt that it is a brand now) I have seen more extreme examples of this in other super-farms such as Daterra. Daterra is a cutting edge farm, capable of producing stellar coffee, and the research they are involved in is invaluable. I know they did a great deal of work on tracing aroma in the cup back to the crop with Illy and I hope eventually some of that research will see the light of day. What surprises me is that they have not distinguished very strongly between their best lots (like the reserve) and then other lots which don’t taste as good. I have seen several roasters proudly claiming the Daterra component of their blend without specifying which one it was and the coffee not tasting great. I thought the idea of the Esmeralda Especial worked well, but was still being muddied by some people so if anything I would have thought they would have distinguished lots even more aggressively.

I feel very strongly that for us to really move forward in speciality coffee we must consistently deliver on our promises to the consumer. Asking them to pay a high price for a cup promises that it will be worth it, and making proud boasts about the coffees we use promises that they will taste something that will be starkly different, discoverable and satisfying. Will every single roast of the Esmeralda be great this year from all the different companies? Does a new, but interested consumer, tasting an average cup of Esmeralda leave them very confused about the prices of the higher lots? Do we risk looking exclusive rather than inclusive to those teetering on the edge of becoming interested and excited about great coffee?

My other thought on the success of the farm has been the double edged sword of the visibility of the Geisha varietal used. I travelled a little bit in Costa Rica last year and every farm I visited had at least a little Geisha planted. Some were more cautious than others in the space they were giving over to the gamble. In three or four years will we see a sudden flood of Geisha on the market (which will immediately drop its desirability) and will it be any good. A while ago I dug through my coffee text books to see if I could find any references to the varietal. I found very little except for a small study carried out abotu 40 years ago in Costa Rica comparing the success of various varietals of which Geisha was won. It lost out primarily because of its lack of yield – less of a problem if you have quality and scarcity on your side, but with lots of people suddenly producing lower yields from their farms scarcity becomes void. No notes are made in the study about increased cup quality, but that study could still easily be dismissed as techniques have moved on and you could also argue that Costa Rica’s quest for yield held it back as an origin producing distinct and amazing coffees until the more recent micro-mill revolution that we are seeing signs of. (if people want me to dig up the study I can do)

On this subject I am very happy to concede I might be wrong. I haven’t spent enough time at origin to feel completely confidant in the above statements, and if Peter or Geoff or anyone else who has spent a lot of time at origin are reading and want to correct me I would be very grateful. I really just want to learn more, and hope that we aren’t all debated-out on this issue which covers just about all of the coffee industry.

The Probat Museum

I am not going to write up the visit to Probat too much – Klaus has already done a great job at the Coffee Collective Blog.

However I think the photoset from the Probat Museum will be of interest to quite a lot of people. I’ve tried to add a little info to the pictures – size of batch, date of manufacture etc…

Probat Museum Photoset

I have the museum guide so if anyone has any questions I will try and answer them. If you

Probat Roaster Museum

Probat Museum Roasters