High Moisture Loss on Light Roasts

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
mjc279
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Joined: 11 years ago

#1: Post by mjc279 »

Hi All,

I'm roasting Indian Arabica beans and one thing I've noticed is that my moisture loss levels are between 17-19%, which seems quite high for City - FC+ roasts. I've tried varying the length of roast (9min - 13 min) Generally, I reach TAT at 2 min and then my drying time has ranged from 4-6 min and FC occurs between 7-9 min.

I'm roasting on a Huky 500 so I have full control over the gas and limited control over the airflow. Does anyone have any ideas on why my moisture loss levels are so high and what I can do to prevent this?

Thanks!

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farmroast
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#2: Post by farmroast »

Speed up the early part(to 300f/150c bean temp,) of the roast. This is when drying occurs but the beans aren't yet really roasting. You might be able to raise your charge temp. a little too. Could it be possible that the beans are on the high moisture side from the start? Thus your getting a slightly higher moisture loss? Compare the cup of 2 roasts with your present moisture loss and one with a faster drying time.
LMWDP #167 "with coffee we create with wine we celebrate"

mjc279 (original poster)
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Joined: 11 years ago

#3: Post by mjc279 (original poster) »

Hi Ed,

Thanks for the reply. I did a 3.5 min drying time (which is pretty much the minimum for my set up) and that reduced the moisture loss to 15.5%. That may be lower limit for the beans I am using given my level of roast. Btw, the beans are around 11% moisture, which seems pretty standard.

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endlesscycles
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#4: Post by endlesscycles »

Any lower than 87% yield is neither a light roast nor is it attributable to loss of moisture alone.
-Marshall Hance
Asheville, NC

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the_trystero
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#5: Post by the_trystero »

Can you elaborate on that Marshall? Are you saying you can't do a light roast that is very dry? And on the second part are you implying that one would be losing bean mass, too?
"A screaming comes across the sky..." - Thomas Pynchon

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endlesscycles
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#6: Post by endlesscycles »

I call a light roast one that features minimal roast notes; Maillard, Caramel, or otherwise: where acidity and sweetness are the dominate to absolute flavor experiences. Green coffee should be between 10-12% moisture content so if there is much more than 10-12% loss, then either roast reactions are to blame or the coffee was inappropriately wet begin with: there is no other explanation (other than "floor" loss).
-Marshall Hance
Asheville, NC

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the_trystero
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#7: Post by the_trystero »

Ah, thank you. When I was first starting out I was using longer Diedrich type profiles and I was getting up to 17% weight loss, the lower temp roasts didn't necessarily have a lot of roasts notes but they were pretty flat.
"A screaming comes across the sky..." - Thomas Pynchon