hist-brewing: crystal malts
George de Piro
gdepiro at mindspring.com
Tue May 28 08:48:43 PDT 2002
Some stuff has recently been written about the purpose and production of
crystal malt. Some of the information was incorrect (most notably, the
fermentability of crystal malt).
Crystal malt is made by a kilning process different from that used to
produce most other malts. It is during the germination that differences
first occur: during the last 30 hours or so the germination temperature is
raised to about 120F to allow thorough protein breakdown. The presence of a
lot of amino acids is desirable (as you will see shortly).
In the early days of its production, dry pale malt was rewetted to a
moisture content of about 44%. These days, the wet, green malt is used
(saves time and energy). The malt is kilned in a closed roasting drum at
140-175F. It is during this time that the starch in the malt is
saccharified, in the same manner that it is in the mash tun. There is
relatively little sugar in the malt before this step.
After an hour or so the malt is dried and roasted by opening the kiln vents
and raising the temperature. The exact procedure used at this step
determines the color and flavor of the crystal malt. All crystal malts are
dried to about 6% moisture.
This relatively complex kilning process causes chemical reactions (called
Maillard reactions) that combine the sugars in the malt with the amino acids
to form melanoidins. Melanoidins are what give the malt its characteristic
flavor and aroma. That's why it was important to form a lot of amino acids
during the germination. These sugar-amino acid complexes are not
fermentable nor are they broken down by amylases in the mash tun.
That is why using crystal malt, or its close cousins Vienna and Munich
malts, adds malty sweetness to the beer. It also raises the final gravity
of the beer (because of the lack of fermentability). Crystal malts lack
diastatic power, but Vienna and Munich malts can convert starch to sugar in
the mash tun.
A great source of information about modern malting is _Technology Brewing
and Malting_ by Wolfgang Kunze. It is well worth the high price to serious
brewers (and maltsters!).
George de Piro
C.H. Evans Brewing Company
at the Albany Pump Station
Malted Barley Appreciation Society
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