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.

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….

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.

GMOs

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!

I didn’t expect to find some stages of coffee roasting to produce such unpleasant effects, or flavours in the cup. Just sniffing the cupping bowls was enough to put me off! Hard to describe, and once water hits it is very different to the aromas you’ll get when using the trier during the roast.

I think it is definitely a worthwhile experience. The only word of caution for those thinking about it is to do with grinding raw/barely roasted coffee. It is incredibly tough stuff, and I was glad to have a VTA6 running full speed to drop the coffee into!

I posted about the little experiment online and got an interesting tweet in response. I had a spare moment this evening, so I went upstairs and rebrewed everything to see what the numbers would say.

Each bowl was done at 60g/l and had the same grind and steep time. I then poured each bowl (rather messily I might add) through a dry v60 paper into another bowl to let it cool. (There is a certain joy in making an absolute mess doing this stuff, knowing there is no one to tell you off!)

I then measured each one in the Extract Mojo. A few very important points before we look at the graph. This is based on a single cupping bowl, and a single experiment. There is plenty of room for error here. Secondly – the refractometer measures the liquid’s refractive index. Software is required to convert this to a strength of coffee liquid. That software has not been created to do accurate calculations for green/barely roasted coffee so the data shouldn’t be considered accurate. (This should be considered no more serious than Tim and I experimenting with the K-ONE written up here!)

Also – I spilled a lot!

Even so – we get an interesting line:

Extraction in a cupping bowl versus roast time

I should add that the numbers (in terms of time) are not accurate and the final sample is more than a minute ahead of the one before it, perhaps explaining the leap. First crack is evident in the jump at around 11 minutes (I realise now this is actually 12 minutes as we’re missing a sample from earlier on – apologies!)

I haven’t tried this particular product (Nescafe Green blend), but having done this cupping today I am fairly sure that Nescafe may well have created something even more disgusting than their regular instant coffee. Impressive work….

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.

Below is an email exchange between Deaton Pigot, Chris Kornman (both roaster with Intelligentsia) and myself. It had come about after a comment I’d made on someone else’s blog about there being no sugars in roasted coffee.

As becomes evident in the exchange – there really is a need to better define what we are talking about when we use the term sugars.

I wish I could say that all my emails are like this, that every day is an in depth discussion of theory combined with our experiences.

Unfortunately this conversation didn’t get any further – work has a terrible way of getting in the way of things like this. I can only speak for myself here, but feel free to pick apart things I’ve gotten wrong or misunderstood. If people would like to contribute anything – please post in the comments.

So we got interested in this “no sugars” claim by JH below, and Josh &
I did some digging.

Sucrose (aka white table sugar, chemical formula C12H22O11) has a
melting point at around 370F (so sucrose, if present in coffee, would
caramelize at or before 1st Crack.) It breaks down into water vapor
(H20) and carbon dioxide (C02).

According to our colleagues Henry Schwartzberg (Professor Emeritus,
University of Massachusetts) and Joachim Eichner (Praxis International
Inc), during the roast, Polysaccharide (Starch chains containing sugar
polymers) Hydrolysis (water breakdown that splits polymers) in the
cell walls of roasting coffee results in the creation of sugars and
oligosaccharides (simple sugar chains). Also, sugars break down to
form Aliphatic (fatty) acids.

So roasting both creates and decays sugars.

Rapid decay begins later in the roast, (11min according to HS & JE),
so likely during or after first crack. The decay of sugars also
produces alcohols & furfural (“…an aromatic aldehyde… Its chemical
formula is C5H4O2. In its pure state, it is a colorless oily liquid
with the odor of almonds, but upon exposure to air it quickly becomes
yellow” – Wiki).

It seems unlikely that full degradation would take place before the
end of 2nd crack, however.

So, yes, there are sugars in roasted coffee.

-ck

Hey James,

I am emailing you because of your comment on the Double shot blog about
sugars left in coffee after roasting. I am sure all of us would love to hear
your thoughts on our mail chain. That is of course if you have the time to
answer.

Hope you are well!

Kind regards

Deaton

Chris and Josh that is a great read! Out here we (or at least I) have bought
into the Staub theory of developing sucrose. IE Polysaccharide split into
monosaccharide, creating a foundation of sucrose that would essentially be
dug into the later stages of the roast.

I went into it in some detail here

http://deaton.wordpress.com/2009/07/12/balancing-act-sweetness/

Plus some of it here as well.

http://deaton.wordpress.com/2009/05/07/how-sweet-is-your-cup/

I know that in James comment he stated;

“Nothing to do with sugars – of which there are none left in roasted coffee,
certainly not simple sugars which react away through maillard, caramlisation
and strecker degradation reactions.”

So it leaves me wondering what sugars he believes are left in the bean after
roasting, as we all know we do perceive varying levels of sweetness.

Hey Deaton,

I could well be wrong – it’s usually the case.

I will dig out the reading I’d done on this – by sugars I meant simple sugars, rather than long chain complex carbohydrates.
No doubt there is sweetness, but more things than simple sugars create the sensation of sweetness on our tongue. Sweetness reception, like bitterness reception, is complex and only reasonably understood.
I find the sweetness of coffee to be unlike the sweetness of simple sugars. I’ve had very sweet shots, for example, but not ones I would describe as sugary.

Give me a day and I will either get pwned or add something interesting.

Kind regards,
James Hoffmann

Hi Deaton,

I think the tricky one here is going to be pinning down a useful definition of sugars.
Once polysaccharide chains get longer they are perceived as being less and less sweet. In the past i used an 18-chain multidextrose to make non-sweet syrups.

The simple sugars, as would be perceived as having a strong sweetness, are very reactive during roasting – through maillard, strecker and caramelisation. Certainly there are some longer chain sugars in the mix.
Most of the research has been done on lower quality coffees, which will always leave us a little in the dark I guess.

Having dug through a couple of textbooks I am up to the following to support my initial statement on the lack of sugar in roasted coffee. If you want the full paper titles referenced then let me know and I will dig them out.
When talking about sugars I am talking about low molecular weight carbohydrates (R.J. Clarke’s definition). On a side note – related to the original post – it seems Petracco et al (1999) isolated a polysaccharide that actually increased foam stability. I digress….

Trugo & Macrae (1985) did a study that showed 97% sucrose loss in light roasted coffee, creeping up to 99% in a dark roast. Hughes and Thorpe (1987) came up with 0.24% and 0.34% sucrose in roasted coffees. Sucrose can hydrolise into glucose and fructose but both degrade thermally more readily than sucrose.
Noyes and Chu (1993) found 0.1% sugars in 21 roasted Brazilian coffees – though most of this (0.08%) was sucrose.

My reading implies that most of the polysaccharides in coffee are extremely stable through the roasting process – according to Bradbury and Halliday (1990), and hydrolysis would have to happen at lower temperatures when there was still water available. I couldn’t find data on water activity and roasting temperatures – to understand when hydrolysis would stop. Will keep looking.

I guess what I would look to argue is the breakdown of the polysaccharides – which ones are breaking down, into what size chains? Do these chains have detectable sweetness? What molecular weight do we use to decide a cut of point for sugars?

Food for thought…..

Kind regards,
James Hoffmann

Related Reading

For reference this older post on the Maillard Reaction, Strecker Degradation and Caramelisation may be of interest.

Maier (1985)¹  compared the chemical composition of traditional and fast roasted coffees, using samples of similar roast colour, and found that the water-soluble extract (soluble solids) increased as the roasting time decreased.  The content of specific substances (such as saccharose) changed with the roasting, indicating that chemical compositions of traditional and fast roasted coffee are similar but not identical.  As expected, fine grind of coffee samples led to an increased amount of extract.  Interestingly the difference in the soluble yield between traditional and fast roasted coffee was dimished by fine grinding. This supports the thesis that fast roasted coffee shows increased brew strength due to structural but not chemical changes.

I hope to have some time this weekend to look at a few more things, I just wanted to keep the debate going.  There is some more info on bean swelling that I want to post up too.

1. Maier, H.G. (1985) Zur Zusammensetzung kurzzeitgerosteter Kaffees. Lebensmittelchem. Gerichtl. Chem., 39, 25-9

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

When approaching a coffee and brewing it using an espresso machine you are often searching for an ‘ideal’ recipe for that coffee.  For many of us knowing as much about that coffee as possible often helps make intuitive judgements about things like dose and brew temp.  If I get my science wrong then please, please shoot me down. ³

One of the things that broke my head about roasting early on was the discovery that the longer/darker you roast the less potential solubles you have.  This may seem obvious to some but it always felt like the roasting process created many new flavours but one must distinguish between flavours and solubles.  This explains why instant coffee is roasting very fast and relatively light – they are interested in a percentage yield so the more solubles the better, regardless of taste.

Knowing this then made something I had experienced make apparent sense – darker roasts generally prefer higher doses, because you need more coffee to get more solubles to get a nice, thick and pleasant espresso.  But after a moments thought it didn’t make sense.  This would mean that you would get a thicker, heavier cup with a higher TDS measurement from lighter roasts but lighter roasts generally produced delicious but lighter bodied cups.  What nudged me towards density was how we approach very high grown coffees versus lower grown coffees.

Higher grown coffees (and let me make a broad sweeping generalisation here) have a much higher acidity than their lower grown brethren.  When brewed as espresso they can easily yield extremely acidic and unbalanced cups and, taking unbalanced and pronounced acidity as a sign of underextraction, I found that higher brewing temperatures helped to produce a more balanced cup.

What do lighter roasts and high grown coffees have in common:  higher densities.  Though there was more to extract (in theory) you had to work a lot harder to do it.  Therefore reducing the dose of a lighter roast/higher grown coffee gave you a higher ratio of water/energy to coffee to help extract a tasty cup.  (I often think of heat energy as some sort of currency, with which you can buy solubles.  The more heat, the more you extract/purchase.)

This is all well and good for convenient examples – high grown, light roasts versus low grown darker roasts.  Give me a clean prepped coffee from relatively low altitudes in Brasil, roast it into 2nd and I will likely be dosing quite high and not brewing too hot.  I’ll certainly be dosing it very different from how I might brew a lot of Aricha as a straight shot.

But what about a light roast of a low grown coffee, or a dark roast of something grown super high up?  This is what lead me to wanting to find a way to measure and compare the densities of coffee beans to see if there was correlation between the density of the end product and an ideal brew temperture of particularly effective dose.

So – if I have had such a good idea why don’t I do all the research and then publish it all at the end of it and try and stamp it “Hoffmann’s theory” or something equally absurd? (Apart from the fact that it is absurd).  Because I want to generate a little discussion about this.  I want people to weigh in and tell me I am being stupid/simplistic and to suggest better ways to test these ideas.  I want to understand espresso better so I can make better tasting drinks and translate coffee’s journey more transparently in the cup. ⁴

I really hope people will offer their opinions on this idea, shoot it down or take it and run with it.  I am going to start doing some basic testing and see what happens.  Lots of little experiments appeal. ⁵

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.
3. There is another post in the works about the value of being wrong and discussing it afterwards – yes, I have a big wrongness to confess to…..
4. I know this is a wordy post and all, and I would have put some nice photos in but my camera is dead
5. For example – if I roast two coffees til their densities match – will they grind the same, and at the same dose will they extract the same?  Would they be ideal, therefore, to blend together to get the most out of each of them.  This probably shouldn’t be a footnote, but it is.  So there.

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…..

Stumptown ruined that for me.  During our West Coast trip in 2007 we were hanging out with the former roaster Joel, chatting about the UG15 he was roasting on (we were just buying ours at the time), and having a great time.  Joel disappeared to the bar and came back with a shot for Anette and one for me.  It was very tasty, sweet, full bodied and clean.  It definitely wasn’t Hairbender.  I was nearly floored when he told me it was their decaf.  That caused a problem: I no longer had an excuse.

Anette does a great job roasting decaf, and I think that experience is one of the many reasons high.  As our memories improve and elevate that particular espresso it means our own bar will constantly be lifting.

I think we make a grave mistake alienating decaf drinks with tonnes of pre-ground, nasty coffee brewed without much care.  These are people who are buying coffee because they like the taste.  We are supposed to love these people – they aren’t the ones suffering through awful espressos or instant coffee just to get their caffeine fix.  And yet they are the people least catered to in the industry.  A shame.

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.

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 Museum Roasters