Weight Loss During Roasting

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
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Brewzologist
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#1: Post by Brewzologist »

While I measure weight loss for every roast, I admit I don't do anything with it. What do others do with this data?

BodieZoffa

#2: Post by BodieZoffa »

I weigh every batch before/after. Of course there might be slight variation batch to batch each season, but I still rely on it to determine development. I ultimately judge by appearance and aroma as I have been roasting totally deaf over 3 yrs now. Wanna talk about a rude awakening trying to aim for 1/2 C when you no longer hear anything. Of course I measure temps at various points to help consistency, but monitoring moisture loss definitely helps as well.

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Brewzologist (original poster)
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#3: Post by Brewzologist (original poster) »

Bodie; Yep, I weigh before/after using Artisan and my moisture loss is usually around 13% +- 2%. But how are you using it to determine development?

All else being equal I use my Artisan profiles for judging/improving my roasts, but other than glancing at the moisture loss figure I don't use it. I suppose if it was way off the norm I might look into things more, but that has never been the case.

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yakster
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#4: Post by yakster »

Weight loss + roast levels.

Behmor needs more heat? (for the old Sivetz chart, also shown below)

Numbers may change and give you an indication of your starting moisture level of green coffee, as in the case if your roasting older greens. I'm normally seeing 14% weight loss for my Bullet roasts.

-Chris

LMWDP # 272

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Brewzologist (original poster)
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#5: Post by Brewzologist (original poster) »

Thanks Chris. That kind validates my thinking that moisture loss for a given green and roast degree is a good QC check for roasting, but perhaps not otherwise beneficial. Kinda like measuring roast color too; nice to know but I'm more likely to make roast adjustments based on the profile than what a densitometer tells me.

N3Roaster

#6: Post by N3Roaster »

Just to be that person, are you measuring moisture loss or are you measuring weight loss? The former isn't terribly useful for anything because you're going to drive out all or nearly all of the moisture. Weight loss (which may be mostly moisture, especially on lighter roasts, but includes many other things as well), on the other hand, is primarily useful as a check on batch to batch consistency. If a given coffee roasted to a given plan gets you something out of line with expectation or if you notice a long term trend in a direction over many roasts that's a strong clue to investigate the cause further. A one off something went wrong could be measurement error, a failure to follow the roasting plan, accidentally loading the wrong coffee, or a few other less common things. A long term trend is typically indicative of storage issues where someone might want to periodically check to see if the roasting plan needs to be adjusted due to those changes to keep the flavor profile consistent, or if storage improvements can be made, or see about using forward contracts to spread coffee deliveries out in time rather than getting everything in at once. Those considerations are useful in a coffee roasting business, but if I were doing this as a home roaster I probably wouldn't bother with the end weight or calculation unless I were just curious about it for some reason.
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Brewzologist (original poster)
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#7: Post by Brewzologist (original poster) »

Hah Neal! Well.... you ARE being that person! 8) But you are correct I am referring to weight loss, not moisture loss. Corrected the title and OP to reflect this. Good catch.

Appreciate your insights. I just watched Rob Hoos presentation in last week's Roast Summit where he conveyed similar thoughts on the value of tracking weight loss.