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Hottop B2K Roasting for Sweetness using Environmental Temperature Readings
Bearpaw
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Posted on 07/28/2013 8:23 PM
Hello Everyone, beautiful day in Tennessee!

The following is a Hottop B2K discussion based on my learnings about roasting for sweetness. It follows the logic and learning in my post ?Toward a Unified Theory of Roast Development for Sweetness? under ?Coffee Roasting? on the Homeroasters.org forum. Also posted today.

If you read that post, it seems to indicate that steady controlled progression of Rate of Roast using heat and fan controls is useful beginning after the initial heat rebound phase to 200F and the beans begin throwing off moisture.

On the Hottop, Randy Glass? profile graphs make it clear that the bean temperature lags behind the environmental probe until around 300F, when the two curves cross, and then the beans eventually overtop the environmental temperature, by about 20 degrees at beginning of second crack. So BT is below but ramping up in 200?s, dead even at 300, and 20 degrees higher by 410 or so ET or 2C. First is always just after 370 environmental temperature on the Hottop B2K.

So in my recent roasts, I have dropped at over 300 ET on the B2K, and changed the way I take notes on my roasts. I note the ET each minute. I know when I want to be back around 200, then 240, 300, then 330, then 370, then watch to end. (on the Hottop ET 240 for me should be very close to Deaton Pigot?s 230 Bean temp as noted in My post of today under Roasting Coffee). 330 as an ET reading should be very close to Deaton?s 340 mark. So my drying time from 240ET to 300ET equals the first two thirds, roughly of Deaton?s sugar development time. So I need to make sure I have about 5 minutes total into 240ET to 330ET. Then I have a short time to put in some heat and then ramp back down to control exothermics. This will be the trickiest part to master and will happen inside a minute, I am anticipating.

Instead of waiting for these temperature mileposts to do fan and heat adjustments, I found myself looking to change heat and fan early on as needed to get the rate of roast to hit those temps respectively at about times of 2,4, 6, 8, 10 ending at 13 minutes or so.

I think I could hit those time targets with 8 ounces, but in practice I am using 250 grams, and my roasts are coming in at 14-15 minutes but they are sparkling like champagne. So times are more like 2.5, 5.5, 8.5, 11, 14 or 15. The sweetness is definitely there. I chose 250 grams because manufacturer recommends, the beans might expand a little closer to the thermocouple at the most crucial point in the roast, and it does work out with five pound bags, thank you Barrie.

Noting temps by the minute has totally changed the way I control the roaster. Instead of looking at the milestones as times to let her rip or cool way down and monkey with the fan, I am trying to control the rate of progression from ET 300 to 330, for example, to be 2 or 2.5 minutes. I am watching the Rate of Rise and playing the heat and fan, instead of looking at temperature goals and adjusting them at those points. The fan goes to 25% when water starts coming out of the beans and stays that way going up toward the end if I need to adjust. Heat is adjusted slightly downward during the Poly-Mono Saccharide boogie, and I am controlling the roast from the get-go.

I saved the profile and can tweak it as needed for Kona Vs Mexico if one starts running away early on. I plan to work out and save a hard and softer bean version later and make two profiles. Since the machine is adjusting heat and sometimes fan for me almost by the minute I can watch the rate of ET rise with the time and just make minimal changes. I know what ET will be 1C and 2C and can easily stop earlier than second if need be. So many thanks to Barrie and Ken about their responses to my posts on sweetness development. You pointed me in the right direction!

Here is a Natural processed Mexico Nayarita from two days ago, the first roast I did with my new notetaking approach.
Drop 325, 250 grams, Played the fan and heater like my guitar, kept the rate going.
Minute Env Temp Notes:
1 197 Bean temp lower than ET till minute 7
2 231
3 258
4 273
5 284 Got a little slow here perhaps?
6 295 6.5 minutes to 300
7 305 Bean Temp higher at this point
8 323 Pyrolysis probably beginning at 8.5
9 341
10 357 1c at 10:50
11 374
12 382
13 399
14 410 Drop FC+ Beans 428 or thereabouts 10 Sec 2C
Deep mahogany, no oils on outside

Coffee is simply stellar, sparkling and sweet. Kona roast went a little different on ramp-up but caught up 10 minutes in, then I slowed it a bit and hit first about 11 and half minutes. Very sweet also, Full City but might need to be speeded up as well.

Well, that?s the news from the Tennessee hills. Listen to John Hiatt?s ?How Bad?s the Coffee; How Good?s the Pie? if you haven?t heard it already.

God Bless Y?all. It?s all good.
Bearpaw
Gene Cafe, Behmor, Aeropress, various pourover, biggins, heirloom coffeepots, Crossland CC1 with VST 18 and 15 gram baskets.

"How Good's the Coffee; How Bad's the Pie!"
 
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