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Roast size for cast iron/whirly pop/KKTO?
AMRoberts
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Posted on 05/16/2018 9:38 AM
Apologies if this isn't the correct forum, but it is kinda-sorta a cross-design question.

I'm learning how heat changes green coffee into roast coffee using a modded popcorn popper, but the small batch size is making it tedious to meet our weekly needs. So of course I'm contemplating the next roaster Grin

I have an outdoor propane burner/grill, so thoughts of trying a cast iron skillet or a Whirly Pop are in the mix. My question is about determining the charge size for these devices. Is the theory/best-practice with these roasters:

1. Charge size is less than covering the bottom of the pan, so that when bean expansion happens at first crack you continue to have (mostly) a single layer of beans, in contact with the bottom.

2. Charge size is what will cover the bottom of the pan in a single layer at the start of the roast (when first crack expansion happens there will be partial multi-layering).

3. Charge size isn't constrained to a single layer, a multi-layer depth of greens works just fine you just empirically determine batch size as driven by amount of available heat, desired roast time, etc?

4. Something else?

I'm looking for some rough guidance that will let me understand how much I'll be able to scale up with an X-inch pan diameter.

Also, does a KKTO follow the same constraints? The YouTube videos I've seen of running KKTOs look like more than single-layer thickness of beans. Because there is convective in addition to conductive heating?

Thanks,
Alan
 
renatoa
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Posted on 05/16/2018 9:59 AM
Succeeded to roast up to 800 grams of greens in a Ikea 23 cm diameter 3 litres capacity steamer insert, code 30152346.
Turbo oven lid based setup, but with added IR heat, versus majoritar convection as is the original TO.

Beans were multiple layered, estimating at least five layers. Did a test to see how much is a single bean layer and found about 150 grams.
Didn't tried 1kg because even at 800 grams they start to jump outside the pot, due to small 8 cm height.
Agitator is a 60 rpm 2 blades stainless steel paddle.
Edited by renatoa on 05/29/2018 4:48 AM
 
AMRoberts
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Posted on 05/16/2018 1:36 PM

Quote

renatoa wrote:

Succeeded to roast up to 800 grams of greens in a Ikea 23 cm diameter 3 litres capacity steamer insert, code 30152346. TO lid based setup, but with added IR heat versus majoritar convection as is the original TO.
...


Thanks renatoa. ~600g of roasted greens per week takes care of the daily brewed coffee at our house, so the fact that a TO could handle that in a single roast makes it very tempting.

The downside for me is the space/storage needed. I can imagine a cast iron skillet (possibly even with a U-frame that flys a motor turning a kinda-sorta KKTO whisk style stirring paddle), or a Whirly Pop fitting in the deck box that is beside the grill. A KKTO is going to get more negative points with my wife.

You mentioned "added IR heat" ... Was this adding a bottom heating element, or the mod I keep noticing where people change/remove some metalwork in the TO head unit?

Cheers,
Alan
 
renatoa
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Posted on 05/16/2018 2:31 PM
None, added a 900 W carbon fiber heater tube, same shape as the halogen but smaller, 12 cm dia.
But removing halogene protection plate works as well.
 
Ozo
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Posted on 08/09/2018 2:20 PM
I roast with a Whirly pop powered with a drill but I only roast 300 grams of green beans at a time but do two roasts to total 600 grams of green. Still, that roasts pretty fast to full city+ because each load is small. I roast at fairly high temp I guess but it spins so fast I get a very consistent roast. Of course you must then deal with cooling them.

I am in the process of upgrading the stainless steel WP to a stainless steel Victorio. It is extremely well made and has a flex drive rather than gears. The top of the WP is its weak point and those weaknesses are all resolved with the Victorio. I even like the name better.

You said "I have an outdoor propane burner/grill, so thoughts of trying a cast iron skillet or a Whirly Pop are in the mix. My question is about determining the charge size for these devices. Is the theory/best-practice with these roasters". If you spend more you could convert the grill to a rotisserie. Drum baskets are available for those. If the speed is too slow they can be powered with a drill. They will roast a lot depending on size of course. I am sure you will get plenty of help with that here.

Good luck with what ever roaster you choose.BBQ grill
Edited by Ozo on 08/09/2018 2:38 PM
 
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