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

#251: Post by GDM528 »

Jake's challenge accepted.

Left-hand profile is my die-sour-die profile, and the right-hand is a I-don't-understand-light-roast-people profile:

Forgot to mention an important point: I set the fan speed to a constant 80% for the entire roast. Ramping it around during the roast changes the heat transfer rate and breaks my feeble math skillz. I also stick to 65g-ish batch sizes so the greens circulate freely.

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#252: Post by Jake_G »

I stick to 65g batches, as well.

Anyway, that's what I would try to ensure I had good dev on a natural (kill the grassiness) without taking it too far into medium territory on the roast meter. I could usually get them (natural Ethiopias) to the 105-110 range on the DIY roast meter with this type of profile and have a coffee that was bright with acidity and let the funky sugary business shine through in a pleasant way. Assuming the greens were any good...

A note on the fan speed, is that I typically use a declining fan speed starting at 80 and linearly declining to 60 or so. My maths skills are no better then Gary's. But this seems to work well and as a bonus, I never had an errant bean ejected with the chaff...

It makes more sense for an power profile to have the fan speed drop, because constant power with less air = higher inlet temp, but it works fine here, too. My logic is that since the beans lose mass, they need less airflow to keep the BT changing, and since we want BT to change less and less as the roast progresses, this seems doubly like a good idea (or at least a reasonable one).
LMWDP #704


#253: Post by GDM528 »

I've only tried about a dozen different greens so far, but the combination of 50-70g batch size and 80% fan speed, averages less than one ejected bean per roasting session - and the ejected bean deserved it. I consider the occasional ejection to be a sort of quality control 'feature' :)

I posit that with three input variables: batch size, fan speed, and temperature, it's possible to find more than one combination of those variables to create a good 'recipe'. Many ways to succeed here.

I found that if I hold two of the three variables (batch size and fan speed) constant, there's a nearly 1:1 relationship between inlet temperature and BT, which is really handy. However, that has also made me very reluctant to mess with batch size or fan speed. I sense another experiment coming on, to see how changing the fan speed alters the relationship between inlet temperature and BT...


#254: Post by viteaux »

Ran some batches this weekend using Gary's I don't understand light roast people profile. I also stretched Jake's stretched profile another 15 seconds. Gonna give the beans a rest and will report back. Also, dropped my batch to 65g, I have been running 75g. Thanks again for the help!