How Hot for a Loring

Discuss roast levels and profiles for espresso, equipment for roasting coffee.

#1: Post by NYFilter93 »

We roast on a Loring S15 and have been playing around with batch size and charge temp. Recently, our parameters have been:

Batch size: 25 lbs
9:26 total roast time
First crack: 8:03
Development time ratio: 14.7%
Start temp: 481F
Charge temp: 515F
End temp: 462

We have had nice balance of sweetness and acidity, but it has overall tasted flat overall. We have thought about increasing our charge temp in the roaster, but is there a limit to how much you can increase the heat in a Loring relative to batch size?


#2: Post by Milligan »

I'm not familiar with Loring equipment but you seem to be going very dark. I'd imagine most coffee tastes rather flat at that temp. Are you roasting extremely dark? Most specialty roasters with a Loring focus on light single origins. You may want to contact Loring directly since their roaster is quite a bit different than most. Seeing how this is typically a home roaster forums, I think your responses may be rather limiting.

You seem to be flying through a roast that big with that high of an end temp. 14% development time ratio at 467 end temp :shock:

NYFilter93 (original poster)

#3: Post by NYFilter93 (original poster) »

We actually aim for a well developed light roast. We used to roast at 12% development but found they tasted flat.

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#4: Post by Chert »

Reduce Charge temp to about 420F.
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#5: Post by Milligan »

NYFilter93 wrote:We actually aim for a well developed light roast. We used to roast at 12% development but found they tasted flat.
Okay. I'm thrown off by the end temps. Perhaps they are different on a Loring than on other roasters. 462F would be end of 2nd crack on my drum roaster and fluid bed.

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#6: Post by drgary »

I have a very different home roaster,* but the principle may be the same as what has already been suggested. No matter what I did my roasts were coming out flat. I had been slavishly following the roast curve of a few years ago that brought out the best in a light roasted Ethiopian natural that cupped well at a gathering with Rob Hoos.** But I never could get back there -- until I lowered charge temperature by a lot. Doing so reduced moisture loss, again by a lot. And now all of my roasts are coming out juicy and revealing more origin flavors. I had typically charged at 440-450°F environmental temp and was pressed to get less than about 13.8% moisture loss, even with lighter roasts. I am now charging at about 370°F environmental temp and am getting about 11% moisture loss at a similar drop temp. This created a breakthrough in quality. I'm thrilled. My roasts are now also much less likely to crash during first crack. Even without a crash-and-flick baked roast, my coffees were flat compared to now.

So, what about that earlier roast that nailed it? Maybe my recording was off and the charge happened later than the start temps shown in the curve. Whatever the difference is between then and now, I've got to work with what my probes are telling me today, and they're only indicative of what's going on in the beans.

* I'm roasting on a 1Kg North TJ-067 propane roaster with a perforated drum. Because the drum is perforated, I pay more attention to starting ET and track that carefully along with BT to provide enough temp separation that the ET will guide BT well.

** You might consult with Rob, who is a Loring expert. He could probably suggest roast parameters that would put you on the right track.

What I WOULD do for a good cup of coffee!

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#7: Post by Almico »

What is the difference between start temp and charge temp? What temp are you hitting 1C?

I agree, the temps seem very high. Hard to believe the beans are not getting scorched.

FWIW, I roast 32# in a SF-75 (half-batch) and charge around 365*F, drop at 388*F for lighter roasts with total time around 10:30. 1C temp around 370* for calibration. For a full batch or 65# I would charge around 415*F.

You are roasting very hot and very fast.

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#8: Post by drgary »

I've split off a request for help with roasting basics to this thread:

Please help me reach the next level in home roasting

What I WOULD do for a good cup of coffee!


#9: Post by archipelago »

Can you verify those stats? 462º on an S15 with OEM probe would be extremely dark. Crack on that machine at 80-85% capacity tends to occur between 390-400.

Another thing to note - really you should be using your return air temp to charge (515 would be wildly high) since it's a more stable measure that BT and will give you a better readout on the thermal energy of the system (make sure your inlet temps are appropriately high as well). 8 min to crack isn't that fast - I often roast in under 7 min start to finish - but it does require that you manage the beginning of the roast appropriately so as not to get scorched or smoky flavors.

I wrote a blog post on one approach that may be helpful.
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