HomeRoast Digest


Topic: Temp readings are relative was Re: +second crack? (3 msgs / 157 lines)
1) From: Homeroaster
It's hard to get accurate temperature readings in an air roaster.  The air 
coming into the roast chamber is around 500F but varies from roaster to 
roaster, so a probe stuck into a 3 or 4 ounce bean mass will likely have a 
higher reading than what the beans actually are.  The best a thermometer can 
do is give you 'benchmarks' that alert you to when the various processes are 
happening.  Make notes as to how the thermometer correlates to those events 
such as when the beans begin to tan and turn brown due to the Maillard 
reaction (sugars and amino acids) and caramelization (sugars and sugars)
Here's a video...http://www.onnetworks.com/videos/food-science/the-maillard-reactionThe Maillard reactions (non-enzymatic browning) begin after the beans heat 
to around 250F.  Caramelization of the sugars begins at different times for 
different sugars.
Caramelization temperatures Sugar Temperature
      Fructose  230F
      Galactose  320F
      Glucose  320F
      Maltose  356F
      Sucrose  320F
Here's a very heavy reference on coffee and sugars...http://jxb.oxfordjournals.org/cgi/content/full/57/12/3243But if you can plod through it, there is a bunch of interesting stuff to 
hide away in your brain for reference.
So if you can mark where the coffee begins to tan, where the smells change, 
where first crack begins and ends, where second crack begins, and where you 
remove the beans for cooling, then you will have a great reference for 
future roasts of that bean type.
*********************
Ed Needham
"to absurdity and beyond!"http://www.homeroaster.com*********************

2) From: miKe mcKoffee
Ed,
Thanks for the reference link. PDF saved and printing for "light =
reading"
 and absortion later!
Kona Konnaisseur miKe mcKoffeehttp://www.mckoffee.com/Ultimately the quest for Koffee Nirvana is a solitary path. To know I =">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/
 
<Snip>

3) From: Michael Dhabolt
Ed,
Great reference: (http://jxb.oxfordjournals.org/cgi/content/full/57/12/3243).  Heavy
reading but brought into focus several issues that I hadn't previously
had a good handle on.
Thanks.
Mike (just plain)


HomeRoast Digest