In this post I summarise the last seminar I attended at the Norwegian Barista Championships this spring. It was hosted by former world champion barista Tim Wendelboe and focussed on coffee roasting. The following is what I understood from this seminar.
Profile roasting, or roasting profile
As a coffee drinker, I find it interesting to get to know the various roasters' profiles, or roasting personalities so to say. I believe each of the four Norwegian roasters I've gotten to know best have their own rather distinct style. The smallest, Madelynn coffee, have a fairly dark roasting profile resulting in more chocolatey and "brown" aromas with less acidity (and perhaps fruitiness) compared to the other "extreme" among the four of Tim Wendelboe. The coffees from Wendelboe seem to me as extremely clean and rich in acidity, but with slender body. Kaffa roasters, on the other hand, are on the lighter side of roasting but with more full-bodied coffees compared to Wendelboe (some of Kaffa's natural/dry processed coffees are among my all time favourites, I must admit). Finally, Solberg & Hansen being by far the largest speciality coffee roaster in Norway, produces such a wide variety of coffees and roasts that the wide variety might be said to constitute their profile, rather than a specific roasting ideal.
Note that these are my personal impressions and nothing more, but it is quite interesting to note differences in ideal and philosophy when listening to roasters and tasting their coffee. Also, it's even more fun when you start noticing these differences when tasting their coffees.
My understanding is that the term "roasting profile" can have two different meanings. Firstly, it can be understood as the preferred flavour characteristics which the roaster wants to achieve (example). Secondly, it can mean the time/temperature curve (profile, recipe) which is followed during roasting (example). Of course these two are closely related, but they are still two different things. I'm not sure what is the official definition is, if it exists, but it seems that the latter definition predominates among professionals (and on wikipedia). So, what is to be understood if we switch the two words to become "profile roasting"? Not exactly sure, to be honest...
Main issues in roasting coffee according to Tim
Some issues that Tim told about and was discussed were:
- Roasting coffee is a matter of dealing with numerous variables and many of these are constantly changing: ambient temperature in the room while roasting, moisture content in the beans, humidity in the room, conditions of the beans, variations among batches of coffee etc. etc. Thus, if you're serious about quality it is not possible to use one and the same recipe over and over again. Certainly not on coffee different sources and areas/countries, but even so if you should buy the exactly same coffee from the same producer twice! It is a matter of try and fail no matter what.
- Roasting is literally going part of the way towards burning the beans, i.e. combustion. In fact, at one point during roasting the temperature will start rising by itself, which is an indication of the coffee almost starting to burn (technically: endotermic reaction is followed by an exothermic reaction). Coffee Collective in Copenhagen did a post on this in which I commented on the thermodynamics. The harder a coffee is roasted, the closer you get to the state of charcoal, and in the extreme cases you'd simply end up with ashes (see below). The first picture in this post is taken at Coffee Collective during a roasting; a marvellous experience drinking excellent coffee with the family and following the coffee develop.
- Scandinavian coffee is generally lighter roasted than coffee from central/southern Europe and the US. The very extreme was a sample of Starbucks French roast which was really pitch black. At that stage of roasting very much of the character is literally burnt away, and the coffee will taste the same no matter what coffee you put into the roaster (no point paying good money for expensive coffee if you're going to burn away all the flavour). In that respect, the Starbucks French roast was one of the blackest objects I've ever seen and might be a candidate for a pure black object, which is in fact quite difficult to achieve in the chemical sense ;) In the other extreme, very lightly or under-roasted, the coffee might take on green grassy or pea-like flavours. The figure below is a graphic representation of my personal impressions of the roasters I'm most familiar with. I'd say that eventhough Madelynn's coffee is rated rather dark, it is still lighter than much of the coffee you'd get in central/south Europe and the US.
- CO2 gas is formed inside the beans due to the combustion reactions. Lighter roasts give lower internal CO2 pressure because less CO2 is produced. Lower internal pressure gives a coffee that keeps better during storage because the CO2 is a rather inert gas (does not react) and that way protects the coffee. This is particularly because CO2 moving out of the beans transports natural oils and fats that are prone to go old/rancid. If you see coffee beans glisten and from oil on the surface, it is either roaster rather dark or it is getting old (or a little of both).
- Whatever mentioned above, apart from Starbucks, concerns small scale speciality coffee roasting. Large scale roasting needs to follow quite different rules because much larger amounts of heat needs to be handled; not higher temperatures but heating of 400 kg coffe up to 250 °C is a rather different ballgame than 40 kg. Not to say when you want to cool it down to ambient temperature in just a few minutes. Thus, large scale operators commonly use water spray to cool the fresh roasted coffee to avoid over-roasting. This results in "opening of the pores in the beans"(?) --> rapid degassing (70% of the CO2 lost within a day or so) resulting in rapid maturation and rapid staling.1
To round off this seminar posting series, I thought this illustrative video from Sweet Maria's coffee gives a good illustration of the various steps the coffee goes through during roasting. I can BTW recommend videos from Sweet Maria's Youtube channel in general; lots of interesting stuff.
1 Roasted whole bean coffee is at its best between one and three weeks after roasting, after which it deteriorates (non-water-spray-cooled, that is). From the day of roasting and a week on, the coffee might have a smoky aroma from the roasting, hence the recommended delay. Buying your coffee at a supermarket, you'll seldom have any knowledge about when it was roasted, and how long it has been sitting on the shelf.