Temperature Midway Point

The Midway Temperature Point has been spreading as a concept the last couple of years and as far as I know I came up with the concept (as I mention it is so simple that it might have been 'invented' by others without me knowing it) for a specific purpose and I see it used outside this purpose which I think is misleading. This podcast sheds light of where I think the concept came from and how it is sometimes slightly misunderstood (if my understanding is correct).
In the podcast I refer to this video 17 min in: https://youtu.be/xE296OquIZ0?t=1030 

Transcript

I would like to talk a bit about The Temperature Midway point in coffee roasting. And for those of you who don’t know, is the bean temperature midway between the bean temperature at first crack and second crack on a given roaster. As roasters has different temperature probes with different thickness and placement these temperatures can be quite different on different roasters, so it is handy to map out as one of the first things when you approach a new roaster you don’t know (as I often do as a consultant).

The reason I got the idea to make a quick podcast about his was that I with great surprise and a bit of excitement that I saw The Mid Point Temperature concept 17 minutes into “Giesen Webinar - Roasting defects, build roast profiles from scratch” (link in the description: https://youtu.be/xE296OquIZ0?t=1030) with Willem Boot and Marcus Young. When I started coffee roasting with NO experience at all in 2005, I was reading Willem Boot’s articles in Roast Magazine and got introduced to all the concepts I have been building my knowledge and skills on since. So it was exciting to see that he now uses one of my concepts in his education! A quick disclaimer: This concept is so simple and from a technical perspective so obvious that I will not rule out, that somebody else have been doing this calculation for some practical purpose that I don’t know about. But I can tell you that I came up with this during an SCAE creators group meeting in Copenhagen the 1st of June 2016 and by then it was at least new to me.

The reason I have been surprised to see this used around the world for the last few years is that it was a concept never intended to be used outside an SCA roasting trainer’s toolbox. The purpose of the concept was to create a education relevant roast degree even if SCA roasting trainers not necessarily had color reading equipment to be calibrated up against. We talked about the difficulties with different roast color standards which made it difficult to communicate specific colors throughout the global SCA coffee roasting trainer community. So, I thought that we should try to come up with a simple way of communicating a relevant roast color for education. Since most of the emphasis of the Intermediate and Professional roasting exam test is on nailing color and modulating development time without changing the color it was important to be able to communicate a roast color that was easy to work with. If it was too light it would be difficult to create a long development time as the time itself would quickly make the color exceed a light reference color. And if the reference color was too dark it would be difficult to succeed with sensory detection of different development time for a series of very dark roasts.

So, I thought too close to first crack, and it is too light to be easy to modulate development time and too close to second crack and it would be considered too dark amongst most specialty coffee professionals to be really transparent for both terroir and roast profile. Notice that I do acknowledge that this is a relative preference statement, but I felt it was safe to do as the global specialty coffee community tends to roast to maximum second crack. It is really easy to notice both 1st and 2nd crack and take notes of the bean temperature for these cracks and taking the average of these two bean temperatures. This gives you the temperature point in between the two cracks and then you end up with a point that is not too close to first crack, where it would be difficult to modulate development time, and not too close to second crack to be too dark to detect subtle flavor changes. The simplicity of this made us decide that we would recommend trainers to aim for the midway temperature point when advising students of a reference roast for practice and exams. It was never intended to be anything else than an internal concept for trainers to use!

Two years later after the merging of SCAA and SCAE the work with the curriculum was a collaboration between former SCAE and SCAA creators and sometimes it was a bit difficult to follow and be part of all the information flowing in the group and to the SCA education curriculum administration and I was a bit annoyed when I saw that even though it was never discussed during creator meetings the midway point suddenly appeared as a concept students needed to know, describe and calculate in the written test! Since this has been part of the student curriculum, I have now seen the concept used around the world and now it seems that it has turned into a roast color where terms as ‘balanced’, ‘medium’ or ‘sweet spot’ is attributed. The reason I react to this is that if this concept for some people is associated with me, I have to make it clear that this was not the purpose because it completely violates the principles with which we work with our background in sensory and consumer science. Here it is extremely important not to mix technical concepts with preference concepts as all questions of preference should be referring to a specific customer segment that has proven to have this preference. Customers are different and there are not technical aspects of a roast that can be standard of predicting ‘all consumers’.

That said, from a technical point of view I have already agreed that most specialty coffee roasters would stay inside the range between first and second crack so this far I agree that there is a relevant range for most product ranges and I find it useful to map out this range early on and carefully get to know your roaster’s heat source when navigating this range which is the fundamental exercise of my new online e-learning course called Roast Profile Design Basics. Notice that this course does not teach you to create a roast profile which is ‘balanced’, ‘medium’ or the ‘sweet spot’ but it does teach you to map out the relevant ranges of time and color for you to map out consumer preferences for different consumer groups and then go home and quickly create a perfect roast profile for the particular consumer segment for whom you have specifically mapped out the preference profile! And the Midway point is an important part of this exercise. But not a preferred sweet spot in itself.