HomeRoast Digest


Topic: weight loss vs deg or roast (25 msgs / 1109 lines)
1) From: Dave Ehrenkranz
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Now that I can hear cracks (yea Behmor!) I am trying to better  
understand where I am in my degree of roast. When I look at the  
pictures at the  Pictorial Guide to the Roast Process http://
www.sweetmarias.com/roasting-VisualGuideV2.html) and compare to my  
beans I think I may be roasting beyond what I thought I was based on  
when the cracks arrive.
I would think a good indicator may also be the percent of wt loss.  
Are others keeping track of this and if so could you please share  
that info? It would help me calibrate where I am. So far with my  
Behmor I am seeing the following weight losses for the degrees of  
roast I thought I was hitting.
FC - FC+	17.24%
City+	16.34%
dave
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Now that I can hear cracks (yea =
Behmor!) I am trying to better understand where I am in my degree of =
roast. When I look at the pictures at the  Pictorial Guide to the =
Roast Process (http://www=.sweetmarias.com/roasting-VisualGuideV2.html) and compare to my =
beans I think I may be roasting beyond what I thought I was based on =
when the cracks arrive.
I would think a good = indicator may also be the percent of wt loss. Are others keeping track = of this and if so could you please share that info? It would help me = calibrate where I am. So far with my Behmor I am seeing the following = weight losses for the degrees of roast I thought I was = hitting. FC - = FC+17.24%City+16.34%
dave
= --Apple-Mail-15-137628785--

2) From: Dave Ehrenkranz
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Just a quick resend in hopes someone has some information to share.  
Or is the consensus that weight loss is not a reliable indicator of  
where one is in the degree of roast. I can think of reasons why it  
would be unreliable but my guess is it should be a good indicator.
Thoughts and/or data please.
dave
<Snip>
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Just a quick resend in hopes =
someone has some information to share. Or is the consensus that weight =
loss is not a reliable indicator of where one is in the degree of roast. =
I can think of reasons why it would be unreliable but my guess is it =
should be a good indicator.
Thoughts and/or data = please.dave
Now = that I can hear cracks (yea Behmor!) I am trying to better understand = where I am in my degree of roast. When I look at the pictures at = the  Pictorial Guide to the Roast Process (http://www=.sweetmarias.com/roasting-VisualGuideV2.html) and compare to my = beans I think I may be roasting beyond what I thought I was based on = when the cracks arrive.
I would think a good = indicator may also be the percent of wt loss. Are others keeping track = of this and if so could you please share that info? It would help me = calibrate where I am. So far with my Behmor I am seeing the following = weight losses for the degrees of roast I thought I was = hitting. FC - = FC+17.24%City+16.34%
dave<= BR = class="khtml-block-placeholder">= --Apple-Mail-16-239286048--

3) From: Vicki Smith
Hi Dave, I am reaching deep into my memory because I am too tired to 
look deep into the archives. There is an article in Roast Magazine that 
talks about a correlation between weight loss and degree of roast, 
though it is not the main point in the article. I know I wrote about it 
probably six or nine months ago.
I did bookmark the article though:http://www.roastmagazine.com/roasting101/leaving/leaving.htmlvicki
Dave Ehrenkranz wrote:
<Snip>

4) From: Rich
I suspect that it is bean Dependant.  Today, I had a 13% loss to FC with 
  Ethiopia Org. Sidamo DP -Special Selection.  I checked just because 
you mentioned it.
Dave Ehrenkranz wrote:
<Snip>

5) From: Steve
It probably would be a good way to gauge roast for a given crop of
beans.. Something maybe to help dial into a more exact measurement of
roast level between runs, if you can nail down, e.g., where City
begins and Vienna ends.
On Nov 18, 10:18 pm, Dave Ehrenkranz  wrote:
<Snip>

6) From: Dave Ehrenkranz
Vicki,
Thanks for the reference. According to the weight losses of
17.24% (FC - FC+?) and  16.34%  {City+ ?)
which I recently saw with my Behmor are in the light medium to medium  
range.
Thanks again, I will try to search the archives.
dave
  On Nov 18, 2007, at 7:25 PM, Vicki Smith wrote:
<Snip>

7) From: Dave Ehrenkranz
My guess is it is not only bean dependent but also profile dependent.  
Thanks for the input.
dave
On Nov 18, 2007, at 7:30 PM, Rich wrote:
<Snip>

8) From: Bonnie Polkinghorn
Dave,
I am also curious about the weight loss and degree of roast.  I do log
this, but alas, I am at work and my notebook is at home.  I'll post
some of my findings this evening.  Maybe I am under-roasting, because
I recall most of my roasts (C+ - FC)  in the 11-13% range.  I roast
mainly decaf, but I like to roast regular to give as gifts and keep my
skills up with the color, smells  and chaff of regular.
Thank you,
Bonnie P.
Santa Rosa, CA
On Nov 17, 2007 3:04 PM, Dave Ehrenkranz  wrote:
<Snip>

9) From: Dave Ehrenkranz
Bonnie,
I would love to see your log when you get a chance. I just finished  
looking at the archives and the weight losses I am seeing agree with  
what others have reported for the degree of roast I was aiming for.
<Snip>
Which is interesting in that I think my beans are darker than what is  
indicated at the Pictorial Guide to the Roast Process
http://www.sweetmarias.com/roasting-VisualGuideV2.html)for the same degree of roast.
I wonder if the smaller weight losses you are seeing are because you  
are roasting decaf. I also roast decaf bean for drinking in the  
evenings and I will check and record weight losses when next I roast  
some decaf. I have not yet roasted any decaf in my Behmor but will soon.
dave
On Nov 19, 2007, at 7:47 AM, Bonnie Polkinghorn wrote:
<Snip>

10) From: Robert Joslin
Bonnie and Dave
     At one time I kept very accurate pre and post roast weights.  Looking
back at the numbers for a two year period (about 135 roasts) I have found
very little difference in weight loss of roasted beans, regardless of
origin, variety, or method of processing (wet, dry, etc.).  Bean weight loss
does vary inversely with length of roast and probably with initial moisture
content of the green bean, although I've never been able to measure that
particular parameter.  The range of loss for all roasts (most were 460g
loads) over this period varies from 14.2 to 16.7 percent  with most roasts
running somewhere in the 15% range.  The great majority of these roasts
were in the city + to full city range, although I once did a vienna by
accident and noted a 19% loss.  The beans went on the compost heap.
My OPINION:  attempting to judge roast level by post roast weight may be
possible, but it seems awkward and there are easier and more reliable and
precise ways to accomplish the same
end.
Happy Roasting All You New Behmor Owners
Josh
P.S. Bonnie:  You have the most interesting name.  Sounds downright
Dickensian!  Love it.
On Nov 19, 2007 9:47 AM, Bonnie Polkinghorn 
wrote:
<Snip>

11) From: Robert Joslin
CLARIFICATION...........roasted bean WEIGHT varies inversely with roast
time.  Roasted bean WEIGHT LOSS varies directly.  Sorry.  I'd like to blame
my bifocals but its really my brain!
On Nov 19, 2007 1:38 PM, Robert Joslin  wrote:
<Snip>

12) From: Erik Snapper
I log all the pre and post weights, and it's a pretty strong correlation.
Generally it ranges from 15% (City) to 17.5% (FC+). If it gets up past 18%
it's usually too dark for me, but still drinkable for people that really
like dark roast.
I've noticed that it's not fully reliable though. If I'm roasting some older
beans, I get less weight loss (such as 15% through 2nd crack), possibly
because they've already lost some moisture in storage.
Even though it's not perfect, I find it a useful indicator, especially since
it's so easy to measure.
Generally I see something like this with the Gene Cafe and fresh beans:
 14.5 - 16.0 : City to City+
15.5 - 17.5 : FC to FC+
17.5 - 18.5 : Vienna
18.5 and up : Mistake
On Nov 17, 2007 3:04 PM, Dave Ehrenkranz  wrote:
<Snip>

13) From: raymanowen
"...weight loss is not a reliable indicator of where one is in the degree of
roast. I can think of reasons why it would be unreliable but my guess is it
should be a good indicator."
Consensus of both brain cells here, there is only a small fraction of the
bean's weight that is actual H2O mass. The water weight loss vs degree of
roast is an interesting concept, but stating the % loss or gain to 4
significant figures is fantasy.
Unless you have a laboratory balance, you can't even weigh them to 4
significant figures, so the original data couldn't support the conclusion.
How would you keep track of the % H2O loss to evaluate the roast progress
and know when to stop?
Isn't it kind of SNAFU to weigh the beans, roast the beans, stop the roast,
cool the beans and weigh the beans again so you can calculate the % H2O
loss? What would you do with that information- it would be useless, since
the roast is already done...
Just listen to the beans- they'll tell you when they're done. Hit the brakes
when you get to the City or wherever.
Cheers, Mabuhay -RayO, aka Opa!
My HP-35 can give 10 significant figure calculations with a bright red LED
readout- Wanna play?
On Nov 18, 2007 8:18 PM, Dave Ehrenkranz  wrote:
<Snip>

14) From: Dave Ehrenkranz
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Just finished roasting to FC+ in my Behmor. When I heard the onset of  
second crack I hit cool  and noticed the cracks continued for  a  
short while into cooling stage. I measured a 17.56% weight loss.  
Which is consistent with my earlier observations.
Robert, I understand your statement "attempting to judge roast level  
by post roast weight may be possible, but it seems awkward and there  
are easier and more reliable and precise ways to accomplish the same  
end." But I am trying to better correlate my perceived roast levels  
to the common definitions. With my Behmor I can finally hear the  
cracks and thus roast levels mean more to me. However, I do believe  
my beans are darker than I expected based on the pics at the  
Pictorial Guide to the Roast Process
http://www.sweetmarias.com/roasting-VisualGuideV2.html)dave
On Nov 19, 2007, at 11:53 AM, Robert Joslin wrote:
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Just finished roasting to FC+ =
in my Behmor. When I heard the onset of second crack I hit cool  and =
noticed the cracks continued for  a short while into cooling stage. I =
measured a 17.56% weight loss. Which is consistent with my earlier =
observations.
Robert,= I understand your statement "attempting to judge roast level by post roast weight may be = possible, but it seems awkward and there are easier and more = reliable and precise ways to accomplish the same end." But I am trying to better correlate my = perceived roast levels to the common definitions. With my Behmor I can = finally hear the cracks and thus roast levels mean more to me. However, = I do believe my beans are darker than I expected based on the pics at = the Pictorial Guide to the Roast = Process(dave
On Nov 19, 2007, =">http://www=.sweetmarias.com/roasting-VisualGuideV2.html)
dave
On Nov 19, 2007, = at 11:53 AM, Robert Joslin wrote:
CLARIFICATION...........roasted bean WEIGHT varies = inversely with roast time.  Roasted bean WEIGHT LOSS varies = directly.  Sorry.  I'd like to blame my bifocals but its really my = brain! On Nov 19, 2007 1:38 = PM, Robert Joslin <rljoslin> wrote: = Bonnie and Dave     = At one time I kept very accurate pre and post roast weights.  Looking = back at the numbers for a two year period (about 135 roasts) I have = found very little difference in weight loss of roasted beans, regardless = of origin, variety, or method of processing (wet, dry, etc.).  Bean = weight loss does vary inversely with length of roast and probably with = initial moisture content of the green bean, although I've never been = able to measure that particular parameter.  The range of loss for all = roasts (most were 460g loads) over this period varies from 14.2 to = 16.7 percent  with most roasts running somewhere in the 15% range.  = The great majority of these roasts were in the city + to full city = range, although I once did a vienna by accident and noted a 19% = loss.  The beans went on the compost heap.   My OPINION: =  attempting to judge roast level by post roast weight may be possible, = but it seems awkward and there are easier and more reliable and = precise ways to accomplish the same = end.                        =                          =                          =    Happy Roasting All You New Behmor Owners                      =                          =                          =               Josh   P.S. Bonnie:  You = have the most interesting name.  Sounds downright Dickensian!  Love = it.     = On Nov 19, 2007 9:47 AM, = Bonnie Polkinghorn <bonnie.polkinghorn> wrote: = Dave, I am also = curious about the weight loss and degree of roast.  I do log this, = but alas, I am at work and my notebook is at home.  I'll post some = of my findings this evening.  Maybe I am under-roasting, because I = recall most of my roasts (C+ - FC)  in the 11-13% range.  I = roast mainly decaf, but I like to roast regular to give as gifts and = keep my skills up with the color, smells  and chaff of = regular. Thank you, Bonnie P. Santa Rosa, = CA On Nov 17, 2007 3:04 PM, Dave Ehrenkranz <daveehr = > wrote: > > Now that I can hear cracks (yea = Behmor!) I am trying to better understand where I am in my degree of = roast. When I look at the pictures at the  Pictorial Guide to the = Roast Process ( =http://www.sweetmarias.com/roasting-VisualGuideV2.html)and compare = to my beans I think I may be roasting beyond what I thought I was based = on when the cracks arrive. > > > I would think a good = indicator may also be the percent of wt loss. Are others keeping track = of this and if so could you please share that info? It would help me = calibrate where I am. So far with my Behmor I am seeing the following = weight losses for the degrees of roast I thought I was hitting. = > > > FC - FC+17.24% > = City+16.34% > > > = dave > > =http://lists.sweetmarias.com/mailman/listinfo/homeroastTo change = your personal list settings (digest options, vacations, unsvbscribes) go = to =http://sweetmarias.com/maillistinfo.html#personalsettings= --Apple-Mail-18-300196740--

15) From: Dave Ehrenkranz
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Erik,
Your results certainly agree with what I am seeing so far. Thanks
dave
On Nov 19, 2007, at 12:01 PM, Erik Snapper wrote:
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Erik,Your results certainly =
agree with what I am seeing so far. =
Thanksdave
On Nov 19, 2007, at 12:01 =
PM, Erik Snapper wrote:
I log = all the pre and post weights, and it's a pretty strong correlation. = Generally it ranges from 15% (City) to 17.5% (FC+). If it gets up past = 18% it's usually too dark for me, but still drinkable for people that = really like dark roast. I've noticed that it's not fully = reliable though. If I'm roasting some older beans, I get less weight = loss (such as 15% through 2nd crack), possibly because they've already = lost some moisture in storage. Even though it's not perfect, = I find it a useful indicator, especially since it's so easy to = measure. Generally I see something like this with the Gene = Cafe and fresh beans: 14.5 - 16.0 : City to City+ = 15.5 - 17.5 : FC to FC+ 17.5 - 18.5 : Vienna = 18.5 and up : Mistake   On Nov 17, 2007 3:04 PM, Dave Ehrenkranz <daveehr> = wrote: Now that I can hear cracks (yea Behmor!) = I am trying to better understand where I am in my degree of roast. When = I look at the pictures at the  Pictorial Guide to the Roast Process = ( =http://www.sweetmarias.com/roasting-VisualGuideV2.html)and compare = to my beans I think I may be roasting beyond what I thought I was based = on when the cracks arrive. I would think a good = indicator may also be the percent of wt loss. Are others keeping track = of this and if so could you please share that info? It would help me = calibrate where I am. So far with my Behmor I am seeing the following = weight losses for the degrees of roast I thought I was hitting. = FC - = FC+17.24%City+16.34% dave = = = --Apple-Mail-19-300274185--

16) From: Bonnie Polkinghorn
Thanks Josh,
It is quite!
An old winery that is now closed used to have a Dickens festival every
Thanksgiving weekend, all the people pouring the wine were in period
dress.  It was a wonderful, old fashioned festival.  I miss it, but I
think I'll brew up some hot mulled wine in memory of it.   Hot mulled
wine while preparing to roast some getting ready for Thanksgiving
beans.  On second thought, I better roast the beans first!
-Bonnie Polkinghorn
Santa Rosa, CA
On Nov 19, 2007 11:38 AM, Robert Joslin  wrote:
<Snip>

17) From: Dave Ehrenkranz
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Ray,
I understand your problem with my reporting 4 significant figures,  
but actually my scale weighs to 0.01 gram so my masses actually have  
5 SFs and the amount of weight loss IS calculated to 4 SFs and thus  
so is the % loss. But still I agree trying to define degree of roast  
based on weight loss calculated to 4 SFs is silly.
I am NOT trying to use % weight loss to tell me when to stop the  
roast but rather to have a better handle on where I have ended up. I  
am gaining confidence that I know where to stop (based on cracks) to  
achieve a given degree of roast. I am hoping weight loss will confirm  
my confidence if the data is consistent across a range. Based on my  
limited data so far I am hopeful
Thanks for your thoughts and input. I hope my goals and methods are  
making better sense to you now.
dave
My spreadsheet can give me better than 10 figures even if they are  
NOT significant.
On Nov 19, 2007, at 12:12 PM, raymanowen wrote:
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Ray,I understand your =
problem with my reporting 4 significant figures, but actually my scale =
weighs to 0.01 gram so my masses actually have 5 SFs and the amount of =
weight loss IS calculated to 4 SFs and thus so is the % loss. But still =
I agree trying to define degree of roast based on weight loss calculated =
to 4 SFs is silly.
I am NOT trying to use % = weight loss to tell me when to stop the roast but rather to have a = better handle on where I have ended up. I am gaining confidence that I = know where to stop (based on cracks) to achieve a given degree of roast. = I am hoping weight loss will confirm my confidence if the data is = consistent across a range. Based on my limited data so far I am = hopeful
Thanks = for your thoughts and input. I hope my goals and methods are making = better sense to you now.
daveMy = spreadsheet can give me better than 10 figures even if they are NOT = significant. On Nov 19, 2007, at 12:12 PM, raymanowen = wrote:
"...weight loss is not a reliable indicator of where one = is in the degree of roast. I can think of reasons why it would be = unreliable but my guess is it should be a good = indicator." Consensus of both brain cells here, there is only a = small fraction of the bean's weight that is actual H2O mass. The water = weight loss vs degree of roast is an interesting concept, but stating = the % loss or gain to 4 significant figures is fantasy. Unless = you have a laboratory balance, you can't even weigh them to 4 = significant figures, so the original data couldn't support the = conclusion. How would you keep track of the % H2O loss to = evaluate the roast progress and know when to stop? Isn't it kind = of SNAFU to weigh the beans, roast the beans, stop the roast, cool the = beans and weigh the beans again so you can calculate the % H2O loss? = What would you do with that information- it would be useless, since the = roast is already done... Just listen to the beans- they'll tell = you when they're done. Hit the brakes when you get to the City or = wherever. Cheers, Mabuhay -RayO, aka Opa! My HP-35 can = give 10 significant figure calculations with a bright red LED readout- = Wanna play? On Nov 18, 2007 8:18 PM, = Dave Ehrenkranz <daveehr> = wrote: Just a quick resend in hopes someone has some = information to share. Or is the consensus that weight loss is not a = reliable indicator of where one is in the degree of roast. I can think = of reasons why it would be unreliable but my guess is it should be a = good indicator. Thoughts and/or data = please.dave Now that I = can hear cracks (yea Behmor!) I am trying to better understand where I = am in my degree of roast. When I look at the pictures at the  Pictoria= l Guide to the Roast Process ( http://www.sweetmarias.com/roasting-VisualGuideV2.html)and compare to my beans I think I may be roasting beyond what I = thought I was based on when the cracks arrive. I = would think a good indicator may also be the percent of wt loss. Are = others keeping track of this and if so could you please share that info? = It would help me calibrate where I am. So far with my Behmor I am seeing = the following weight losses for the degrees of roast I thought I was = hitting. FC - FC+ 17.24%City+16.34% dave = --Apple-Mail-20-301671740--

18) From: Homeroaster
My last 5 pound drum roast of a Colombian (no oil showing) was 16.8% weight
loss.  From 5 pounds of green, I get 5- 12 oz. bags with 6.5 oz left over
for sampling, or combining with multiple roasts to make more full bags.
Weight loss can also depend on how much moisture was in the bean at the
start of the roast.  Very fresh, green beans can be higher in moisture than
those that have been sitting in bags in a 'C' grade warehouse somewhere.
*********************
Ed Needham
"to absurdity and beyond!"http://www.homeroaster.com*********************

19) From: Dennis Ryan
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in this article on Roast Magazine's web site:http://roastmagazine.com/roasting101/leaving/leaving.htmlThere is a chart about 1/3'd the way down the page that shows degree  
roast and weight loss.
On Nov 19, 2007, at 11:34 PM, Homeroaster wrote:
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in this article on Roast =
Magazine's web site: There is a chart about 1/3'd the way down the page =">http://=roastmagazine.com/roasting101/leaving/leaving.html
There is a chart about 1/3'd the way down the page = that shows degree roast and weight loss.

On Nov 19, = 2007, at 11:34 PM, Homeroaster wrote:
My last 5 pound drum roast of a Colombian (no oil = showing) was 16.8% weightloss.  From 5 pounds of green, I = get 5- 12 oz. bags with 6.5 oz left overfor = sampling, or combining with multiple roasts to make more full = bags.Weight loss can also depend on = how much moisture was in the bean at thestart of = the roast.  Very fresh, = green beans can be higher in moisture thanthose = that have been sitting in bags in a 'C' grade warehouse = somewhere.*********************Ed Needham"to absurdity = and beyond!"http://www.homeroaster.com*********************----- = Original Message ----- From: "Erik Snapper"To: = <homeroast= s.com>Sent: Monday, November 19, 2007 = 3:01 PMSubject: Re: +weight loss vs deg = or roast I log all the pre and post = weights, and it's a pretty strong correlation.Generally it ranges from 15% (City) to 17.5% (FC+). = If it gets up past 18%it's usually too dark for = me, but still drinkable for people that reallylike dark roast. <SNIP> homeroast mailing listhttp://li=sts.sweetmarias.com/mailman/listinfo/homeroastTo change your personal list settings (digest = options, vacations, unsvbscribes) go to http://=sweetmarias.com/maillistinfo.html#personalsettings = = --Apple-Mail-4-363016880--

20) From: Bonnie Polkinghorn
Thanks Dennis, a fascinating article.
Thanks to everyone, this discussion has been very helpful to me.  It
seems I am way underroasting my beans, I'm stopping the roast too
soon.  Most of my roasts are at 11 - 13% loss.
My very last roast, however, that I roasted for my hubby to bring to
work and also for my brother-in-law for Thanksgiving, a Mexico FTO
Oaxaca Pluma, I did get to 15.5%, I was thinking it got to just before
start of 2nd crack, maybe not, huh?  I have roasted this bean many
times for my brother-in-law, and I consistently get 15 - 16.5% loss on
this particular bean.  A few other regular coffees I have roasted were
also in the 15% range.
Perhaps decafs lose less mass than regular?
I know my roasting method isn't the greatest, the stove top whirley
pop corn popper, but it's what I have.
Thanks again,
Bonnie P.
Santa Rosa, CA
On Nov 20, 2007 5:41 AM, Dennis Ryan  wrote:
<Snip>

21) From: raymanowen
Here's something else to consider-
The water content of the beans at the end of roast (temperature much higher
than the H2O vaporization temperature at standard atmospheric pressure) is
practically Nil.
The % H2O weight loss would depend almost completely on the initial H2O
content at the start of the roast, and almost nothing else.
There was a Cahn balance in the analytical lab at CSM Research Institute
that would read directly to 7 significant figures. It was kept within the
measurement lab's controlled environment, in a glass box on a 10 ton marble
post through the lab's floor on bedrock. I would recalibrate it to
159.00001g (8 sig figs/ capacity was 160g), so it would still be within
specs through the next calibration cycle
To standardize the starting H2O content, you could initialize it to 0
content by putting your greens in a vacuum bell jar for 5 minutes at
0.1Torr. Re-admit air at, say, 50% rh then weigh the batch and start
the roast.
I feel sure the actual barometric pressure might cause variations that would
obliterate any precision like 4 significant figures, and the initial water
content controls the % weight loss.
Just a thought, in case you like playing with long numbers. I just fired up
the HP-35 it has 10 digits, none of which is necessarily significant. It
could add and subtract better than I could, so that's why it replaced the
bamboo Versalog...
Cheers, Mabuhay -RayO, aka Opa!
On Nov 19, 2007 1:38 PM, Dave Ehrenkranz  wrote:
<Snip>
-- 
"When the theme hits the bass, I dance the Jig!" - -Virgil Fox at the Mighty
Wichita (ex- NYC Paramount) WurliTzer- 1976

22) From: Dave Ehrenkranz
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Ray,
Most certainly the %H2O loss is affected by the initial H2O at the  
start of the roast. How much that varies over time and bean variety I  
do not know. But given a specific lot of beans over a few months I  
suspect it doesn't vary too much. But to state "The water content of  
the beans at the end of roast (temperature much higher than the H2O  
vaporization temperature at standard atmospheric pressure) is  
practically Nil" is not fair as the water is not necessary free to  
evaporate as it is tied up (chemically) in the structure of the bean  
and DOES vary as one continues the roast. While 4 SFs is most likely  
overkill and may not truly be warranted 3 SFs does is so far showing  
a trend which is meaningful.
Gotta go get started  on the Turkey and Goose
dave
On Nov 21, 2007, at 10:54 PM, raymanowen wrote:
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Ray,Most certainly the %H2O =
loss is affected by the initial H2O at the start of the roast. How much =
that varies over time and bean variety I do not know. But given a =
specific lot of beans over a few months I suspect it doesn't vary too =
much. But to state "The water content of the beans at the end of roast =
(temperature much higher than the H2O vaporization temperature at =
standard atmospheric pressure) is practically Nil" is not fair as the =
water is not necessary free to evaporate as it is tied up (chemically) =
in the structure of the bean and DOES vary as one continues the roast. =
While 4 SFs is most likely overkill and may not truly be warranted 3 SFs =
does is so far showing a trend which is meaningful.
Gotta go get started  on = the Turkey and Goose
dave = On Nov 21, 2007, at 10:54 PM, raymanowen = wrote:
Here's something else to consider- The water = content of the beans at the end of roast (temperature much higher than = the H2O vaporization temperature at standard atmospheric pressure) is = practically Nil. The % H2O weight loss would depend almost = completely on the initial H2O content at the start of the roast, and = almost nothing else. There was a Cahn balance in the analytical = lab at CSM Research Institute that would read directly to 7 significant = figures. It was kept within the measurement lab's controlled = environment, in a glass box on a 10 ton marble post through the lab's = floor on bedrock. I would recalibrate it to 159.00001g (8 sig figs/ = capacity was 160g), so it would still be within specs through the next = calibration cycle To standardize the starting H2O content, you = could initialize it to 0 content by putting your greens in a vacuum bell = jar for 5 minutes at 0.1 Torr. Re-admit air at, say, 50% rh then weigh = the batch and start the roast. I feel sure the actual barometric = pressure might cause variations that would obliterate any precision like = 4 significant figures, and the initial water content controls the % = weight loss. Just a thought, in case you like playing with long = numbers. I just fired up the HP-35 it has 10 digits, none of which is = necessarily significant. It could add and subtract better than I could, = so that's why it replaced the bamboo Versalog... Cheers, Mabuhay = -RayO, aka Opa! On Nov 19, 2007 = 1:38 PM, Dave Ehrenkranz <daveehr> = wrote: Ray,I understand your problem with my = reporting 4 significant figures, but actually my scale weighs to 0.01 = gram so my masses actually have 5 SFs and the amount of weight loss IS = calculated to 4 SFs and thus so is the % loss. But still I agree trying = to define degree of roast based on weight loss calculated to 4 SFs is = silly. I am NOT trying to use % weight loss to = tell me when to stop the roast but rather to have a better handle on = where I have ended up. I am gaining confidence that I know where to stop = (based on cracks) to achieve a given degree of roast. I am hoping weight = loss will confirm my confidence if the data is consistent across a = range. Based on my limited data so far I am hopeful = Thanks for your thoughts and input. I hope my = goals and methods are making better sense to you = now. daveMy spreadsheet can give me = better than 10 figures even if they are NOT significant. = On Nov = 19, 2007, at 12:12 PM, raymanowen wrote: "...weight loss is not a reliable indicator of where one = is in the degree of roast. I can think of reasons why it would be = unreliable but my guess is it should be a good indicator." = Consensus of both brain cells here, there is only a small = fraction of the bean's weight that is actual H2O mass. The water weight = loss vs degree of roast is an interesting concept, but stating the % = loss or gain to 4 significant figures is fantasy. Unless you = have a laboratory balance, you can't even weigh them to 4 significant = figures, so the original data couldn't support the = conclusion. How would you keep track of the % H2O loss to = evaluate the roast progress and know when to stop? Isn't it kind = of SNAFU to weigh the beans, roast the beans, stop the roast, cool the = beans and weigh the beans again so you can calculate the % H2O loss? = What would you do with that information- it would be useless, since the = roast is already done... Just listen to the beans- they'll tell = you when they're done. Hit the brakes when you get to the City or = wherever. Cheers, Mabuhay -RayO, aka Opa! My HP-35 can = give 10 significant figure calculations with a bright red LED readout- = Wanna play? On Nov 18, 2007 8:18 PM, = Dave Ehrenkranz <daveehr> wrote: Just a quick = resend in hopes someone has some information to share. Or is = the consensus that weight loss is not a reliable indicator of where = one is in the degree of roast. I can think of reasons why it would be = unreliable but my guess is it should be a good indicator. = Thoughts and/or data = please.dave Now that I = can hear cracks (yea Behmor!) I am trying to better understand where I = am in my degree of roast. When I look at the pictures at the  Pictoria= l Guide to the Roast Process ( http://www.sweetmarias.com/roasting-VisualGuideV2.html)and compare to my beans I think I may be roasting beyond what I = thought I was based on when the cracks arrive. I = would think a good indicator may also be the percent of wt loss. Are = others keeping track of this and if so could you please share that info? = It would help me calibrate where I am. So far with my Behmor I am seeing = the following weight losses for the degrees of roast I thought I was = hitting. FC - FC+ 17.24%City+16.34% dave
-- "When the theme hits the bass, I dance the = Jig!" - -Virgil Fox at the Mighty Wichita (ex- NYC Paramount) WurliTzer- = 1976 = --Apple-Mail-28-543988029--

23) From: miKe mcKoffee
Roasted weight versus greens weight is dependent on roast level, heat
method, roast ramps, and initial greens moisture content. All else being
equal a darker degree of roast will yield higher weight loss, electric heat
versus gas heat will yield greater weight loss, slower ramp stages will
yield higher weight loss, higher initial greens moisture content will yield
higher weight loss. 
For a given green roasted with consistent profiles weight loss can be one of
the indicators for judging final roast result.
Kona Konnaisseur miKe mcKoffeehttp://www.mckoffee.com/Ultimately the quest for Koffee Nirvana is a solitary path. To know I must">http://www.mcKonaKoffee.comURL to Rosto mods, FrankenFormer, some recipes etc:http://www.mckoffee.com/Ultimately the quest for Koffee Nirvana is a solitary path. To know I must
first not know. And in knowing know I know not. Each Personal enlightenment
found exploring the many divergent foot steps of Those who have gone before.
Sweet Maria's List - Searchable Archiveshttp://themeyers.org/HomeRoast/

24) From: Michael Wascher
A commercial roaster (small operator, had 5 retail locations at the peak &
then sold to a bigger operation) used weight loss as a QA check. Sampling &
weighing took too long to determine if it was time to dump & cool, but it
was a quantifiable method of comparing your roast to previous roasts of a
particular bean variety.
On Nov 22, 2007 11:18 AM, miKe mcKoffee  wrote:
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-- 
"When I was a boy I was told that anybody could become President. Now I'm
beginning to believe it." --Clarence Darrow

25) From: Justin Marquez
I think that the wt loss is more than just vaporized water.  After all, the
sugars get carmelized (sp?) and break down, evolving CO2.  Probably some
weight changes there, too.  I do agree that the initial moisture contenty
probably has the greatest impact on the wt change, but the darker the roast
the more wt loss will be exhibited "all other things being equal" (which
they rarely are...).
Safe Journeys and Sweet Music
Justin Marquez (CYPRESS, TX)
On Nov 22, 2007 12:54 AM,  wrote:
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HomeRoast Digest