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Topic: HotTop roaster / bean moisture (4 msgs / 109 lines)
1) From: Bob Briggs
Adding moisture to beans is a crude operation in my hands, but it
appears to work very well.  I weigh out a load for the roaster, less 5%,
then bring it up the full-load weight with charcoal-filtered tap water. 
A 300 gram load would be 285 grams of beans and 15 grams of water (if
the target is 5% added water).  The whole procedure is done in a
sealable container (like tupperware).  I seal it, shake it, and put it
in the refrigerater for about 24 hours.  The beans swell up and appear
to be moist clear to the middle at that time.  I've only done 3 such
roasts, but they take a setting at least 2 higher than the dry ones. 
The flavor seems to be better too, but I'm not sure if that is so or why
it should be so.
My bean moisture measurement is cruder still - I took a pre-weighed
sample and put it in a commercial lyophilizer.  The beans were kept at
room temperature under 10 microns of vacuum connected to a -80 Celcius
cold-trap.  After 2 days of that, the weight dropped by less than 2%. 
Any remaining moisture would have to be VERY tightly bound to the
beans.
My beans are stored in Sweet Maria's cloth bags in a kitchen cabinet. 
I don't know what the humidity is, but I'm in Iowa.  We're humid in the
summer and dry in the winter, so it's air-conditioned in the summer. 
Maybe that makes things dry most of the time?
I just got my new drum plate and chip from Baratza / HotTop.  It looks
like the first test (elsewhere) yielded dark and oily on setting 4.  I
suspect that might translate to flame and cinders in my hands.  I think
I might wait for some other reports before I install that chip as I'm
fairly happy with the cool chip Shelly made for me.
The idea of weighing beans on arrival and some weeks later is pretty
good!  I've got some coming tomorrow, I better try that.  I don't think
I should weigh a 5# bag, though.  It might lose weight in a few weeks
from causes other than moisture loss!
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2) From: dewardh
<Snip>
appears to work very well.
Another way of dealing with the moisture variable (the one used by the Rosto 
1500, btw, indirectly if not deliberately) is to "dry and hold" in the roaster, 
and then time the roast *from the hold temperature*.  Any roaster with a slow 
ramp up (like the Alp or the HotTop) will, at some point (around 135C is a good 
"reference point"), produce uniformly dry beans . . . the rest of the roast 
should be timed from that point, pretty much ignoring how long it takes to get 
there.  That largely eliminates the storage humidity variable (from the roast, 
anyway).  It does add another level of complexity to the roaster, which must be 
able to accurately measure bean temperature . . . something which neither the 
Alp nor the HotTop presently do.
Deward
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3) From: Irene and Lubos Palounek
Bob,
thanks for your explanation. Your "moisture adding to beans" procedure is
simple and clever.
"...My bean moisture measurement is cruder still - I took a pre-weighed
sample and put it in a commercial lyophilizer... the beans were kept at room
temperature under 10 microns of vacuum connected to a -80 Celsius
cold-trap..."
Please educate me -- I thought that a lyophilizer is a "freeze-dryer" -- not
something used at room temperature.  Anyhow, I would not consider your bean
moisture measurement a "crude" setup. A lyophilizer is not one of our
kitchen gadgets.
Our box with HotTop updates came yesterday late afternoon. I am not sure
that I like the new "bearing" better than the original one (as it came on
our unit). I think that I will not install the new one.  I remember reading
that some other users also thought that the new plate is not an improvement.
Regards, Lubos
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4) From: Ken Mary
<Snip>
I did a few experiments with bean moistening and found no difference using a
hot air popper. When adding a small amount of water, I did not wet the
beans, but put the water on a paper towel or plastic cap in a sealed jar. If
the bean surface is wet for a long time, you run the risk of mold formation.
I also did some bean *soaking* experiments with exposure time of 2 to 4
hours, then immediate roasting. I never pursued this, the benefits were not
worth the trouble.
One problem I see with moistening is causing more uneven roasts due to the
larger amount of water that must be removed before "roasting" begins. If the
moisture is not equilibrated throughout the bean, or between beans, the
drier parts will roast faster than the wetter parts. 24 hours does not seem
long enough IMO.
<Snip>
Water vapor pressure at 18C is 15.5 mmHg or slightly more than 2% of an
atmosphere. You need an oven set just above 100C to force the moisture out.
You also need higher temp to overcome the surface adsorption energy.
--
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