I am a systems guy. I am naturally inclined to make systems out of processes to create consistency, efficiency and ease. But as I've started roasting coffee that I know really well on the Diedrich, I'm beginning to question coffee-roasting systems.
The reason why is because a system, a tight system, restricts the mind and imagination, and confines what can be done. When I started blogging about roasting on this site, I was clear to state that the results I'm finding are limited to the Probat that we use in this shop, under these conditions. Though from the roaster it seems like I am unearthing universal truths about roasting coffee, I'm not. I'm finding ways that are working for me right now with these coffees on this roaster. And this reality - the wild untamed part of roasting coffee - has become even more evident as we've begun to really get into the details of roasting with the Diedrich.
For instance, I really have not liked how batches were turning out when I was roasting a 6/9/12min profile. On the Probat it's wonderful. On the Diedrich it's dead. It literally kills coffee. Airflow has to do with it, but I think that the drum size is the major contributor (thank you Jackie).
In a larger roaster the coffee is going to have a greater variance of development at 12min than a smaller roaster. When I roast a batch for 12-14min on the Diedrich, which is ideal with the Probat, the coffee is extremely uniform, but has lost something. And whatever that something is, I'm calling it the wild or untamed, I want it present in the cup.
So far the profile that I'm liking the most is Yellowing at 5min, hitting First Crack at 8min, and dropping at 10min. The split is not equal; it's not balanced. And it may not seem like a big deal to have a minute difference between the time spent in Browning versus Development , but it is an enormous difference.
I do think there are principles about roasting that are true. And I think that they are able to be followed in many circumstances. But I think learning principles and perspectives are absolutely more valuable and beneficial than tight systems. Make sense not systems.