kboom1
New member
Learning a new pro roaster and was wondering if anyone has any rules of thumb for finding their charge temp for a particular varital. Mainly starting points for hard bean, soft bean, low grown,high grown,etc.
Finding Charge Temps
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Redswing
New member
Well, I'll suggest something I spose. First off, in my roaster, I have noticed that charge temp is not only tied to bean density and such, but also related to batch size (and also to how long the roaster has been running...the longer its been on, the faster it roasts even at the same temps and gas applied). If I fill my roaster at 100%, I charge about 20*F hotter than a 30% batch or the like.
So for dense high grown washed caffeinated beans not intended for espresso, I charge around 390*F-410*F. For the natural processed Ethiopian and Brazilian beans I'm using for espresso right now, I charge around 350*, aiming for a more gradual drawn out profile. Same for the water processed decaf I have. Low grown softer beans in general a charge temp around 350, high ground denser beans in generaly charge around 400.
Hopefully that helps kick off a conversation for you. What are you roasting on?
So for dense high grown washed caffeinated beans not intended for espresso, I charge around 390*F-410*F. For the natural processed Ethiopian and Brazilian beans I'm using for espresso right now, I charge around 350*, aiming for a more gradual drawn out profile. Same for the water processed decaf I have. Low grown softer beans in general a charge temp around 350, high ground denser beans in generaly charge around 400.
Hopefully that helps kick off a conversation for you. What are you roasting on?
eldub
New member
I like my soft beans and decafs to bottom out at around 200* and the harder beans between there and 236*. As redswing explained above, batch size and length of time the roaster has been running are big factors in charge temp.
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I'm roasting on a new USRC sample roaster (1.2lbs) and have a 3k in the works. Need to get a feel of how the bigger batch sizes will translate from the sample roaster as far as basic charge temps. I roast a lot of ethiopian naturals mainly for espresso also. I'm coming from Behmors and BBQ roasters so learning the best way to find my charge temps is kind of new to me as the pro roasters are different beast all together. Thanks for the great info.
peterjschmidt
Active member
My first suggestion is to find a batch size that will give you the net roast size you want, and stick with it for a long time. Eliminate that variable, and then play with charge temps for different beans. Also, avoid the temptation to max out your batch size, as that will take away some of your options when it comes to how much heat you have to move things along. On my Ambex 2K, with 4 of the 5 jets installed, I can start w/ 3.7# to net 3# for customers and 2 cups' worth for me (for quality control checks), but it means I can't play around too much w/ my charge temps and still get to 1C in a reasonable time.
chast
New member
I have a USRC sample and I usually drop between 400 and 420F. Same with the 3KG. Great sample roaster!!
samuelstafford
New member
I just bought a new San Franciscan SF6 and have been puzzling over charge temps as well. I feel like I'm getting a moderate amount of scorching when charging 3# batches at 400F. It seems almost ashy in the cup.
peterjschmidt
Active member
Like most of roasting, the profiles are shrouded in secrecy. Which I detest, of course.
But I've read in several places and ascribe to myself, that the equilibrium temp - or turn temp, as some call them - when the temp of the beans stops falling and turns to start rising, should be somewhere around 170F. So I adjust charge temp according to batch size to make that happen.
But I've read in several places and ascribe to myself, that the equilibrium temp - or turn temp, as some call them - when the temp of the beans stops falling and turns to start rising, should be somewhere around 170F. So I adjust charge temp according to batch size to make that happen.
eldub
New member
What are the turn around temps when charging at 400*? How are you so sure that it is the charge temp that is causing the scorching? ( I really doubt that the charge temp is scorching your beans.) How hot is the ambient temp when the beans are reaching completion? (That would be more of an issue, imo.)
samuelstafford
New member
Peter - Why the turn at 170F? Does anyone give a reason?
1:30 to 2:00 is pretty quick to take beans at room temp and move them to 170F.
1:30 to 2:00 is pretty quick to take beans at room temp and move them to 170F.
samuelstafford
New member
Eldub - I'm not sure what my ET has been at the end of my roasts. I'll have to check now that I have artistan software up and running. I believe my turnaround times have been somewhere around 200 F. I know that my bean temps have actually dropped on a couple of the roasts during first crack.
peterjschmidt
Active member
I don't recall any specific reasoning, but that seemed to be the consensus when I was looking into it... as far as those roasters who were willing to divulge went.
I don't think that's too fast to go from 70F ambient to 170F, and I also don't think that's a very critical part of the roast with regard to forming flavor compounds etc. I believe it's simply a stage to get through.
eldub
New member
The temp the beans bottom out at is the least of your worries. Stalling out the roast during first crack could be a bigger problem, IMO. Some of my small batches only get down to around 236* and that's OK for hard beans, IMO.
