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Coffee Roasting Defects Pictorial

Postby chang00 on Wed Mar 03, 2010 11:54 pm

Complied several roasting defects from discussions of the Home Roasting Competition. I reproduced some defects on a pan.

Quaker. From under-ripen beans:

Image

Charring. From too hot of heating surface:

Image

Tipping. Again from high heat of roasting surface or in my case, the drum rotation is too slow:

Image

Center line charring. From too much heat from drying phase to 1st crack:

Image

Crater. Generally due to too much heat from 1st crack to 2nd crack:

Image

Under roasting. The bean just finished 1st crack. Notice the approximate 90-degree angle from the flat surface of the bean to the semi-circular bottom. Good for cupping, not so good for daily drinking:

Image


More drinkable roast. Bean expansion after 1st crack. Notice the rounding of the previously mentioned angle:

Image

Bean expansion after 1st crack, from a different angle. The center line is not charred, and the silver skin is evident:

Image
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Postby another_jim on Thu Mar 04, 2010 12:30 am

Fabulous pictorial, I've marked it as an FAQ.

One note. The centerline will go dark again just ahead of the first pops of the second crack (it's a good cue for the lightest roast usable for espresso). The centerline defect should be checked as the beans even out and go darker in color at the end of the first crack.
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Postby Randy G. on Thu Mar 04, 2010 1:19 pm

Is a "Quaker" the same as a "Stinker"? I had not heard the term "Quaker" before (not that this means much).
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Postby farmroast on Thu Mar 04, 2010 2:20 pm

A quaker is an under ripe(light and pale in color). A stinker is over ripe/rotten (black bean). Stinkers will kill a cup.
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Postby farmroast on Thu Mar 04, 2010 3:21 pm

Macro videos of some of the entries from the HB roasting competition showing roasting effects. Produced by Tom of Sweet Marias who was one of the judges
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Postby farmroast on Thu Mar 04, 2010 3:25 pm

Ed Bourgeois
"agitation is important like grinder"
LMWDP #167
http://coffee-roasting.blogspot.com/
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Postby chang00 on Tue Mar 09, 2010 1:28 am

Edited and added "crater" to the pictorial. :D
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Postby yakster on Tue Mar 09, 2010 2:29 am

Craters are also known as a divot or divots, fyi.

Thanks for posting these pictures.
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Postby another_jim on Tue Mar 09, 2010 3:09 am

Small note:

If you roast to a rolling second, the pitting shown in the craters illustration becomes common. If it happens during the second crack, it is not usually regarded as a roasting defect -- at that point they are called divots.

However, I know lots of people who'd call any roast that goes too far into the second crack defective :wink:
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Postby Hamilton on Tue Mar 09, 2010 6:34 pm

That's good to know, Jim. I noticed some of those in my darker roasts (the last couple I went 20-30 second into second crack) and I was wondering if there was a potential problem.
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