First, I think “know” is a big word and wouldn’t use it here. As you can see, I got the temperature readings wrong, and I’m starting to think that there was some bug or miscommunication between the two.
Second, I’m in full agreement with Münchow’s published study. I don’t think there are other factors that determine flavour beside colour and, to a lesser degree, development. I wouldn’t consider other factors if they’re not roasting defects. This, apart from the published results in the study, has also been my practical experience. Now, when you see someone fumbling near the end and raising the fan and dropping power, it means that this was caused before. Playing with the fan is almost never a good thing. But if you have a larger batch and need to keep it going, then you might benefit from raising it later on, but not excessively. I’m guessing that this coffee has a decent amount of chaff even at early stages and, if the fan is not high enough to blow it out, it will cause a steep rise and a sharp fall, once that chaff clears up a bit, which is what this looks like to me. As a footnote I’ll add that some people crank up the fan to 10 a little before dropping the beans to blow out any remaining chaff. This is done near the end because it’s practically the start of cooling, because you’ll see your curve plummet to the bottom.
Last, but not least, I’m taking these guesses because I roast and try different things. If someone else does something, I will try it. I mean, why not? It’s not set in stone how the coffee should be roasted or how exactly it should taste. That’s commodity coffee way of doing things. Over roast and see if you can tell the difference between coffees. I cannot even smell commodity coffee, let alone drink it. I do not understand how people were trained to like the stuff. There’s also a small sample study on the Coffee Mind site that is called “Quality does not sell itself”. Also, when a roast goes wrong for me, by my parameters, I always give it to people who say that it’s still better than what they buy. I mean, I can clearly see it’s nothing I’d dare sell, but they can identify that they’re dealing with higher quality product even as such. So, I’d say that it’s just exposure and also the fact that people drink coffee way too hot, because trained that way. That will certainly have an effect on the palate. There was a study that was trying to link cancer with Yerba Maté, but the conclusion was that it was the temperature at which they consumed it.
Cancer and yerba mate consumption: a review of possible associations - PubMed (nih.gov)
After this digression, I will repeat what I’ve said many times here. Do not try to emulate others. Roast and learn, rinse and repeat. There are guidelines, but there will always be differences between roasters. Not that one is bad and the other is good, just different.
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