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Roasting ground green coffee
boris
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Posted on 01/15/2014 1:55 PM
A friend of mine had this idea, I thought it was pretty clever and made me wonder...

As a general rule, the best flavors remain when roasted using the lowest possible temperatures for the shortest time. Typical roast times are around 6min ~ 15min. The beans would be heated and roasted much quicker if they were ground before roasting - surface area exposed to the heat would be greatly increased.

That makes sense to me- but would it work to roast pre-ground green coffee?
The processed coffee bean is a pretty monolothic structure, so I would expect it to follow the same roasting chemistry - just happen much faster.
 
ginny
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Posted on 01/15/2014 2:34 PM
sorry but that is one of the dumbest things I have ever heard...

ginny


please let us know how it works for you and if the chaff is as good as the beans.


smoking
 
JETROASTER
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Posted on 01/15/2014 3:15 PM
My hunch is that the experiment may not make it past the grinding stage.
Green beans are not very grinder friendly.

Beyond that, a pile of coffee beans is somewhat porous, because the beans are roundish. This allows for heat to envelope each bean. Ground coffee might be a very well insulated mass...working against your original intention.

....unless you're planning to micro-wave :)
-Scott
 
boris
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Posted on 01/15/2014 3:53 PM
Scott,

Agreed a standard blade grinder probably won't "cut it" (ha-ha). But I'm throwing practicality out the window for this concept :)

What would you expect the roast times to do when you roast a pound of:
- Whole green beans
- Green beans cut in 1/2
- Green beans cut in 1/4
- Green beans cut in 1/8

The progression would be to faster roast times, right? There's probably a point where the coffee is ground so much that it starts to insulate, as you say, but I suspect you'd have to get much smaller than 1/8th cuts, as the bean mass is constantly agitated which should help prevent 'clumping'.

If the key to the best roast is low temp + short time, I think this could be a recipe for a great roasted bean with a very limited shelf life.

Chaff management is a big question mark. It could probably be managed with a small amount of airflow in a drum roaster, but wouldn't be easy to get right.

Now I'm regretting building an air roaster instead of a drum - my air roaster would shoot the ground coffee right out of the chamber!

Boris
 
coffeeroastersclub
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Posted on 01/15/2014 4:51 PM

Quote

boris wrote:


As a general rule, the best flavors remain when roasted using the lowest possible temperatures for the shortest time. Typical roast times are around 6min ~ 15min.


If I am not mistaken that is a Michael Sivetz quote. Regarding the cutting up thing you need to know that alot goes on inside the bean after roasting regarding flavor development. I would not want to mess with that very necessary process by ripping into the bean and spilling its guts all over the place. Shock

Maybe think of it with this analogy: Would you really want to get a pork butt and grind it up and lay it flat on a pan and then smoke the resulting ground pork for 2 hours? Or would you want to smoke an intact pork butt for 16 hours then pull it apart and mix afterward?

I guarantee the 16 hour pork butt will be superior. I've done it myself numerous times. woohoo


Len
"If this is coffee, please bring me some tea but if this is tea, please bring me some coffee." ~Abraham Lincoln
 
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jkoll42
Top  #6 Print Post
Posted on 01/15/2014 4:57 PM
Hi Boris - please don't take this in any way as an insult since this board has fostered a lot of innovation, but like G said this is a horrible idea.

There are many many reasons why it is an awful idea but I will list just one which is very not technical and should head this off at the pass without having to babble on.

How fast does roasted coffee take to go stale after being ground? (Hint: about 15 minutes). How long does coffee need to rest after roasting to reach optimal flavor (Hint: a couple to a few days). And there is problem number 1 in a long line of em.

But by all means, give it a shot - we love to see experiments. With particles that small you could just stir over the stove in a skillet. Just make sure you have a very heavy duty grinder - if you doubt this listen to the videos of Tom from Sweet Marias cupping roasts starting at green. His Mahlkonig is not so happy about it!

Jon`
-Jon
Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3
 
allenb
Top  #7 Print Post
Posted on 01/15/2014 5:59 PM
Leaving the obvious grinder burrs potential shortened life span alone for now, there's a few things going on here that could be interesting to ponder.

As Boris alluded to, roast times could be cut way down since the time for heat to penetrate to the core of these small particles would be a small fraction compared to the time it takes to go from the skin of a whole bean to the core. How much time could be taken off the clock is any ones guess but I'd bet it would be substantial.

I'm guessing you'd be able to roast with much lower temperatures resulting in much reduced loss of volatiles.

Could it be that the usual 2 to 5 day rest might be shortened substantially as well?

I see a place for this, if it produced a great roast, for the all in one roaster-grinder-brewer. A big hurdle would be the beefy grinder needed for long term green grinding.

I'm anxious to hear how it tuns out in the cup.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
tamarian
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Posted on 01/15/2014 11:42 PM
Dustin at home barista did this experiment. The roast went well using a skillet, the taste wasn't great, but it might worth trying it darker. Here's the thread: http://www.home-b...28089.html
Wa'il. 1 Kg PID'ed gas-fired fluid bed roaster, GS/3MPS, K10F
 
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boris
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Posted on 01/16/2014 9:24 AM
It's cool that this guy has actually tried it!
One thing I noticed is that he didn't try his coffee until a day later. For pre-ground, I think it's clear that it would stale pretty quickly.
He also mentioned that the water just flowed right over the beans and he didn't get much of an extraction. I didn't understand his aversion to grinding the coffee a bit finer (it seemed too coarse to me).

Anyway, I'm pleased to see he had success using just a pan on his stove. I'm going to give this a shot over the weekend... something always prevents me from working on my roaster, it may as well be coffee!
 
oldgearhead
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Posted on 01/16/2014 11:15 AM
I'm pretty sure that Sivetz as well as some engineers at Nescafe
tried this in the early battles for the 'instant' market.
No oil on my beans...
 
allenb
Top  #11 Print Post
Posted on 01/16/2014 12:12 PM

Quote

tamarian wrote:

Dustin at home barista did this experiment. The roast went well using a skillet, the taste wasn't great, but it might worth trying it darker. Here's the thread: http://www.home-b...28089.html


Allow me to roast some of the best whole beans to be had in one of my skillets and I'll brew you some very mediocre coffee. A skillet in the hands of someone who's roasted for a very long time with it can produce good results but trying to control drying and finish rate of rise is difficult at best for anyone without many hours under their belt. One micro change in the burner setting and you've gone from 25 degrees/minute to 100/minute and the roast is trash.

It would be interesting to hear how this would turn out in a roaster that could handle ground green and be able to run a profile accurately.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
tamarian
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Posted on 01/16/2014 2:36 PM
I think a turbo oven might be best for such experiment? Drums and fluid beds will not agitate it correctly, I think. Radiant heat with slow turning action action may do it.
Wa'il. 1 Kg PID'ed gas-fired fluid bed roaster, GS/3MPS, K10F
 
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allenb
Top  #13 Print Post
Posted on 01/16/2014 2:51 PM
Great idea!. I guess you'd need to modify the stir arm to lightly drag the bottom and maybe an additional arm a little higher up.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
JETROASTER
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Posted on 01/16/2014 4:04 PM
Stainless steel wire wisks? -Scott
 
Koffee Kosmo
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Posted on 01/16/2014 6:34 PM
The roast time Boris noted in the first post is what we do now with whole beans
Never tried roasting ground/broken beans but I'm sure others have and probably experienced poor results

KK
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