Hi all,

I am slowly trying to tweak my process. I have read a bit about the various stages of roasting, and the benefit of having an appropriate amount of time after first crack. I am a little unsure of what others prefer to do here. Is it as beneficial to have an extended 4 minute period after first crack in an air roaster as well as a drum? And if so, I have been a bit unsure how I should regulate my temperature to push second crack out long enough without stalling the roast. Is stalling the roast a concern after first crack? Can I simply hold the roast temp for x time or should I be on a slow rise? Finally, has anyone run up against the final limit where, for example 8 minutes between 1C and 2C = terrible coffee?

Thanks for the help

An air roaster operated with constant heat input tends to run out of steam at the first crack; so the rate at which the beans rise in temperature can slow down too much, and the roast can take too long to finish. Drum roasters operated with constant heat input tend to store up energy early in the roast, and release it at the end; so they tend to finish too quickly.

Profiling means varying the heat to achieve the best roast. In air roasters, this usually requires cutting back the heat early in the roast. In drums, it usually works the other way around, with the heat being cut late in the roast.

On air roasters, I like three to four minutes from the start of the first crack to the end of the roast for brewing and maybe a minute more for espresso. On my new drum, I can do two to four minutes for brewing and three to five for espresso, but the faster finishes only work if I've stretched out the time to the first crack.

Most commercial roaster manufacturers recommend roast times of 8 to 12 minutes overall on air roasters, and 10 to 15 minutes overall on drums.

Thanks Jim. I think I could probably stand to push up 1C on my roasts. Right now I'm hitting first at around 8;30 minutes which may not give me enough room for a long finish. This may be a loaded question, but is there a rule of thumb for how early I might push up first crack to? Working backwards it seems like 6 or 7 minutes might be a bit better range for first crack.

On an air roaster, 3 to 4 minutes to get to 300F bean temperature (or the point most of the bean have gone from the original green/tan to a yellow/beige color), and another 3 to 4 minutes to get to the first crack is about right. On a drum, a minute slower for each is more comfortable and controllable.

These are the times commercial craft roasters currently use for specialty coffee. Twenty years ago, they ran air roasts a few minutes faster and drum roasts a few minutes slower. My feeling, based on about eight years of home roasting and tasting, is that the current profile times taste better for most coffees

Hi Hamilton

On my air roaster I aim for 140C at about 3.5 minutes and 1C at about 8.5minutes - end of roast at about 12min which is just into 2C. Which is pretty similar to Jims figures.
You want a good digital thermometer that displays in tenths of a degree. Reason is you can see if the temp is still moving. Without being able to read that tenth of a degree you are waiting for the number to roll over (almost twice as long with Celsius) after 15 seconds you are wondering if it has stalled.
I manually log the temp every 30 seconds and write down the difference between every 30 seconds.

I don't have no PID. I am the PID.

Rob
ZEN roasting "Be the PID"

Haha, yes, I am my PID as well.

I guess my recent roasts have been pretty close to yours Rob, which is close to what Jim suggested. I am using your design, so I guess that makes sense. I may just be roasting a bit too light. I may just try keeping everything else the same and roasting further into second crack.

Do you have any recommendations on a thermometer? My next order of business is getting a better thermometer. I'd like to have a datalogger and thermocouple at some point, but that seems to be a pretty expensive project.

This unit seems promising. It's small, and you can buy a few and still pay less than a multichannel data logger. I haven't tried it, though.

Wow, that is an amazing value if it works well, Jim.

I have also been pondering the thermocouple Sweet Maria's sells, although it obviously does not have any datalogging capability, the price is great for a straight thermocouple. I'm a bit skeptical based on the price, though.
http://www.sweetmarias.com/prod.roastkits.php

I had a similar thermocouple to SM when I had an Iroast. It works but the actual probe will need to be replaced due to the heat, they are cheap.

Marvin