HomeRoast Digest

Topic: crack sounds (6 msgs / 107 lines)
1) From: Kai-La-Sha
To Jason:
I would liken the first crack sounds to tiny firecrackers.  The pitch of
the sound is complex, as is the volume. Some of the cracks are
surprisingly loud; some are high pitched, some lower. 
The sound of second crack is much softer: a whisper.  It has aptly been
described as sounding like rice crispies when you first pour milk on
them.  The pitch of the second crack sound is quite high, and less
variable in pitch and volume that the first crack.
Before the beans enter second crack, they are usually a uniform dark
brown, and acquire a satin gloss - not oily, but a satin sheen. In fact
the most reliable visual difference between city roast and full city
roast is that smooth sheen.
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2) From: dewardh
brown, and acquire a satin gloss - not oily, but a satin sheen.
This may be an artifact of the difference between wok and air roasting . . . 
but I often (usually?) hear second crack (when I can hear it at all) *before* 
seeing oil, or even, often, "the sheen".  Some varieties make it into a 
"rolling second" that even I can clearly hear with little or no "sheen" at all, 
and I take the appearance of oil as evidence that the roast is "past done". 
 But it varies from variety to variety quite a lot, as does "color" . . . the 
beans we most favor ("aged" Indonesians, Ethiopians and Yemens) typically end 
with anything but a uniform color, and look almost to be a completely different 
"product" from the shiny uniform brown you might get from a "Central".  The 
"visual" clues are perhaps the most idiosyncratic of the "state of roast" 
indicators . . . more variable (from variety to variety) than sound or smell or 
bean mass expansion, and certainly more variable than temperature.  This makes 
it particularly hard for a "beginner" . . . who may try first a Colombian and 
then a Harar without any warning of difference (s)he's going to see.
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3) From: Mike McGinness
From: "dewardh" 
smell or
How very true. I know my consistency at hitting a desired roast improved
greatly after adding temperature monitoring. Still use smell, sound and
sight of course but my primary gauge is temp'.
MM;-) aka Kona Konnaisseur miKe mcKoffee
Dual Variable Transformer Rosto Roasting
Rocky grindin' - Miss Silvia brewin'
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4) From: Ken Mary
Faster roasts will cause the oil or sheen to appear sooner. The gases are
driving the oil to the surface. I have done some relatively fast roasts then
stop and coast to the finish up to 2 minutes into second crack with no oil
or sheen.
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5) From: Jim Gundlach
On Friday, January 17, 2003, at 10:45 AM, dewardh wrote:
One of the problems with the sample pack is there is not enough of each 
type of coffee for a beginner to notice that the differences seen in 
roasting may be due to the coffee, not what they are doing.
Jim Gundlach
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6) From: David Westebbe
It makes sense to use every available indicator.  But the main thing to use
is your brain, which is the only instrument available which will reconcile
divergences between the various other indicators.
Time, temp, smell, appearance, and sound are all good evidence, but only
your brain knows for sure (until your taste buds can confirm the conclusions
you arrived at).
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