Your Roasting Temperatures Don't Make Sense To Me

[Jazz]

Very interesting. If you dont mind me asking, how long between cracks would you go on average. I always try to never go beyond 4 min.

 

[eldub]

I don't have my roasting schedule in front of me but four minutes sounds about right. (Three minutes might be on the acceptable quick side and five on the long.)

 

[PerfectDayCoffee]

I find the sweet marias temps to be way off I first pop at 375° to 388° F and go to like 415 at a ramp between 10° to 3° per minute for a nice city roast. Their end temps are way high- I stop popping way before 426.

 

[eldub]

perfectday: What roaster are you using?

I don't go by sweet marias' guide. I go by the roaster manufactures numbers (US Roaster Corp) as well as the guide in "Home Coffee Roasting," by Kenneth Davids. However, all three sources mentioned above cite roughly the same temps for specific stages of the coffee bean roasting process and my personal experience on our machine corresponds closely to those figures given.

 

[Josh]

No, I'm not making any such claim. I am stating that temperature probe readings will very by machine, placement, and accuracy.

So... if If wikipedia tells me that 2nd crack is at 437f inside the bean, I believe it. However, my machine will read the bean mass probe at 405 when second crack is happening.

As long as my probe is consistent I can track my roast profile and that is what matters.

 

[eldub]

It comes down to accuracy, imo.

But as you say, long a probe is consistent, a roast profile can be tracked.

 

[chast]

Controller Temps

Just because your conntroller says "385" for example, that does not mean that the bean temp is 385 degrees. Controllers need to be calibrated by an offset to get exact temp readings. I have yet to see a calibrated controller on any roaster, at least the ones I have looked at. I have seen controllers read 400 and after placing a ASTM thermometer in the chamber ( not roasters) there has been as much as a 10/12 degree difference on the low side, sometimes on the high side. You can take a hand held thermometer and aim it at the sight glass but that only gives you the temp there.

The average first crack on my roasts start around 376 and that is only a few pops. As it climbs it starts popping like crazy around 382. 2nd crack comes in around 425 depending on the charge size and bean type. My controller could be off by 9 degrees but the current temp readings are what I go by.

JMO
Charlie