Coffee Roasting Defects Pictorial

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

#1: Post by chang00 »

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

Quaker. From under-ripen beans:

Charring. From too hot of heating surface:

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

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

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

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:

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

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

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#2: Post by another_jim »

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.
Jim Schulman

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#3: Post by Randy G. »

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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#4: Post by farmroast »

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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#5: Post by farmroast »

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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#6: Post by farmroast »

LMWDP #167 "with coffee we create with wine we celebrate"

chang00 (original poster)

#7: Post by chang00 (original poster) »

Edited and added "crater" to the pictorial. :D

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#8: Post by yakster »

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

Thanks for posting these pictures.

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#9: Post by another_jim »

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:
Jim Schulman


#10: Post by Hamilton »

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.