A chart of the Popper roast chamber temperature and heat coil power based on the setting of the heat knob, as well as some new tips for roasting!
We have been working on mapping out how the position of the heat knob impacts the temperature in the Popper roast chamber.
This might seems straightforward, but it has been hard to relate the readings to the real world roasting experience. These temperature settings are based on running the roaster empty, and measuring the hot air as it enters the roast chamber. They are not the temperatures measured with coffee in the roast chamber.
Nonetheless, while we continue to improve on Roast Profile refers to the relationship between time and temperature in coffee roasting, with the endpoint being the "degree of roast". Roast profiling is the active manipulation of the "roast curve" or graphed plot of ideas, with coffee in the roast chamber, it seems useful to share this information. The settings were done by an engineer at the factory and I corroborated the temperatures on multiple units here.
Two things to be aware of though. How you measure temperatures, and how a probe is placed matters greatly. That’s why I have been more interested in charting bean temperatures in roasting. But bean temperatures in an air roaster come with additional complications, because they vary by batch size, type of coffee, and how much a probe is actually reading a contact temperature with a bean versus the hot air stream.
The second surprise here is that in the final production unit of Popper, the roast setting between 2 and 3 isn’t meaningful! The power to the coil is the same. This was a surprise to me, even though I had tested the difference in prototypes. And I need to change our “initial roast recommendations” in the literature based on this. If you start at roast at 2, you might as well start it at 3, full heat! In fact, I now think it is best to roast initially at 1:30 on the heat dial (and fan on High … always start roasts on High fan speed!)
On the flip side, the fact that the heat dial has a “dead zone” between 2 and 3 is no shocker either. Any electric appliance with a digital or analog dial like this is going to have a lack of uniformity in the measured effect of incremental change. On an electric stovetop lets say, the difference between a setting of 4 and 5 will not correspond in temperature degrees to a change between 6 and 7. The reality is no control of this kind produces uniform results across the range. (And in fact a gas valve is no better, but at least you can “eyeball it” by looking at the flame!)
So please consider this chart as a starting point to better understanding the process when roasting with Popper!
|Popper Roaster||Low Fan Speed||Low Fan Speed||High Fan Speed||High Fan Speed|
|Heat Knob Position||Coil Power (W)||Temperature (F)||Coil Power (W)||Temperature (F)|
Popper Roast Profile Tips
Roasting with Popper means finding out what works for you … the machine doesn’t have programs or make roast decisions for you. (If you have one I am sure you know this already!) It’s a tool and of course, tools can be used in various ways. So it’s good to learn by experience, your own experience, but here are some general tips that supersede what comes with the printed material with the roaster:
- In our opinion, a good starting roast profile is 90- 100 grams (weighed out), with Fan set to High and Heat set to about 1:30 on the dial (ie, 1:30 on a 12 hour clock face).
- Coffee should rotate initially, even if it is quite slow, and pick up speed in the first 30 seconds – 1 minute
- You might hear the start of First crack in one of two distinct heat-induced pyrolytic reactions in coffee. It is distinguished by a cracking or popping sound in the coffee, and occurs between 390 and 410 degrees Fahrenheit in most coffee as early as 4 minutes into the roast (which would read 6:00 on the digital timer). But first An audible popping sound heard during roasting. In coffee, one refers to "first crack" and "second crack," which come from two different classes of chemical reactions.: An audible popping sound heard during roasting. In coffee, should be slow and extended at these settings. If it is rapid, reduce heat to 1:00 on the heat knob.
- In the middle or toward the end of first crack, reduce the temperature to 1:00 or 12:30 on the heat knob.
- You can Similar to aftertaste, but it refers to the impression as the coffee leaves the palate. Aftertaste is the sensations gathered after the coffee has left the mouth. We combine these to form the "final flavor out the roast this way, or if you want further bean development, headed toward After First Crack, a roast reaction around 440 to 450 degrees that is distinguished by a snapping sound. Second Crack is the second audible clue the roaster-operator receives about the degree-of-roast, following First Crack. Whereas, change the Fan Speed knob to Low setting. This will increase the roast chamber temperature and help the roast develop toward 2nd crack
- If you want a darker roast, add more time. For a few snaps of second crack (where I personally like my A small coffee beverage, about 20 ml, prepared on an espresso machine where pressurized hot water extracted through compressed coffee.: In its most stripped-down, basic form, this is a working definition for espresso: A small), add time. I usually end up adding 1 minute -2 minutes.
- The way of approaching darker roast levels will avoid the “high temp thermal cutoff” which happens at 465 f. When that happens the roaster loses temperature as the heat power coil is off for about 20 seconds. In fact, using a slow development approach, which avoids the temp cutoff, is also a far better roast profile than one that pushes too much heat at the coffee too quickly.