I do tend to like espresso that you might find, "disgustingly acidic". And the roaster(s) whose numbers have influenced me like that kind of light roast too. So maybe that's just it then? Maybe the numbers I'm chasing are only from one narrow corner of the home roasting space?

This has been informative discussion.

-Peter

pcrussell50 wrote: I pretty much always get a mass loss of 14%, where another one of those beliefs I picked up says that's too much and that it ought to be about 11%.

I'm curious to know where 11 % comes from. Are you thinking the % moisture in green coffee before roasting? I never get that low, 14% is pretty normal as a starting point. I checked some old references, I found one for Artisan from 2011 where it correlated loss and roast level as shown below. I'm not sure that this is still current.

City 13.5 - 14.5
City+ 14.5 - 15.5
FC 15.5 - 16.5
FC+ 16.5 - 17.5
Lt. Fr 17.5 - 18.5
French > 18.5

Also, here's an old chart from Sivetz.

yakster wrote:I'm curious to know where 11 % comes from. Are you thinking the % moisture in green coffee before roasting? I never get that low, 14% is pretty normal as a starting point

Great post, thanks. I get that figure from an advanced home roaster friend, who also likes the super light roasts that you need super long low debit pre infusion flow profiling to tame the acidity, and are best done with one of those hyper-aligned, expensive flat burr grinders that you have to be lucky just to get on the waiting list for. So I may be quoting figures that are a bit out of the mainstream, (though they may start to become more relevant as super light roasts and flow profiling grow in representation).

-Peter

To help with your lighter roasts, you definitely need to cool the beans outside of the behmor. Like a shop vac bean cooler. Get some long oven gloves so you don't burn yourself while taking the drum out. I managed to get my forearm when using shorter gloves! Dump out the beans and let the behmor run its cooling cycle.