hist-brewing: Re: Crystal Malt and Torrified Wheat

[Jeff Renner]

Mike Bennett <mjb at efn.org> wrote:

>Scotti <PBLoomis at aol.com> wrote:
>
>  > The sugars crystallize out, and are thereafter much harder
>  > for any amylase enzymes to break down.  They remain complex,
>  > and contribute both mouthfeel and sweetness to the resulting
>  > beer.
>
>This statement is incorrect.  The sugars produced are soluble and will
>be broken down by any amylase present from the base malts used.  I
>believe that this misconception is brought on by homebrew texts that
>instruct the homebrewer to add crystal to their extract beers for more
>sweetness and mouthfeel.  Since extracts don't have active amylase the
>large chain sugars present in the crystal malt won't be broken down.

This is a question that puzzled me, so I asked it four years ago on 
HomeBrew Digest.  Mort O'Sullivan, then a student at the 
International Centre for Brewing and Distilling at Heriot-Watt 
University in Edinburgh, Scotland, answered.  He stated that the 
sugars in crystal malt are indeed resistant to fermentation.  This 
has been my own experience, although I've never done an actual 
experiment.

Below is his original post and his reply to another question.  This 
is an incredible bit of information that I believe is accurate.   I 
hope it is of use to the readers of this list.

Jeff
<><><><><>
Date: Thu, 2 Jul 1998 22:12:04 +0100
From: "Mort O'Sullivan" <tarwater at brew-master.com>
Subject: RE: crystal malt: call for discussion

Jeff Renner calls for a discussion on crystal malt, primarily 
questioning whether it is really true that the sugars from crystal 
malt are less fermentable than those from standard malts.

>It seems to me that there is nothing inherent about this procedure
that
>should produce more unfermentables than a standard mash.  If a
temperature
>regime is used in stewing that would result in higher unfermentables
in a
>conventional mash, the result should be the same.
>
>Now it may be that the stewing is indeed done at such temperatures
>routinely, resulting in high unfermentables.  I think that maltsters
have
>researched the results of temperature regimes, both regarding sugar
>profiles and protein profiles, and control these precisely.  And, of
>course, the caramelization of most crystal malts' sugars adds an
important
>flavor component not easily (or at all?) achieved otherwise.  Perhaps
it is
>these caramelized sugars that are less fermentable than they would be
>uncaramelized?  I don't think so, but I'm trying to think of all of
the
>angles.

These are very good questions. The starting point for creating 
crystal malt is usually well modified green malt at >43% moisture and 
the initial air on temperature is usually 65-70*C. Holding at this 
saccharification temperature is often compared to mashing within the 
kernel, but some important differences should be kept in mind. First, 
at about 43% moisture, the liquor:grist ratio is much lower than in a 
normal mash; and second, the "grist" is never milled but simply 
consists of starch-and-protein-containing endosperm cells whose walls
have been degraded during germination by endoproteases and beta 
glucanases. These conditions limit the amylase enzymes' access to 
substrate compared to normal mashing conditions. There are still 
plenty of reducing sugars released to react with the primary amines 
in Maillard reactions to form the reductones, furans, pyrroles, 
pyrazines and countless intermediates that provide the characteristic 
flavors and colors to crystal and caramel malts. Once caramelized, 
these sugars are no longer sugars, and so are not fermentable by 
yeast.

However, only a small percentage of the sugars actually undergo 
Maillard reactions and so presumably there are plenty of other 
sugars, dextrins, and partially degraded starch molecules remaining 
that would eventually contribute to fermentability, especially after 
they are mashed in the presence of the "healthy" enzymes from the 
normal malt that makes up the majority of your grist. But this is not 
the case. Why?

Starch molecules in barley are approximately 25% amylose, and 75% 
amylopectin. Due to the limited enzyme mobility described above, the 
amylopectin is preferentially broken down because the complexity of 
the molecules "entraps" enzymes in microchannels on the surface of 
the amylopectin molecules. The much longer, straight-chain amylose 
molecules are solubilized, but survive the process relatively 
unscathed. During the later, high temperature stages of kilning and 
subsequent cooling, these solubilized amylose molecules tend to 
recrystallize in a process called retrogradation. For reasons not 
entirely understood, these recrystallized amylose molecules are very 
resistant to enzymic hydrolysis and so will not yield fermentable 
sugars.

It has also been noted by many researchers that regardless of the 
type of malt being produced, there is an inverse relationship between 
the time spent at high temperature in kilning and the fermentability 
of a malt.  As crystal and caramel malts can spend quite a long time 
at temperatures as high as 150*C, it makes sense that their 
fermentability may be severely reduced.

Hope this helps.

Mort O'Sullivan
Edinburgh, Scotland

-=-=-=-=-=-=-
Date: Wed, 15 Jul 1998 22:30:30 +0100
From: "Mort O'Sullivan" <tarwater at brew-master.com>
Subject: Crystal Malt Questions

I was afraid someone might ask for clarification regarding my earlier 
post. Thanks, Steve.

Starch retrogradation is a pretty complex physical phenomenon and 
could be better explained by a rheologist than a brewer. But I'll try 
to tell you what I know and show you where I found the information.

>In capsule form it says:
>malt is 25% amylose and 75% amylopectin (this checks out)
>stewing of crystal malt favors amylopectin-lysis [- hmm why ? all enzymes
>are just as short of water. - Isn't BA smaller to start with ?]]

Even in a normal mash, amylopectin is broken down faster than 
amylose, which is explained by the fact that the complex structure of 
amylopectin molecules tends to entrap amylase enzymes. In conditions 
such as stewing crystal malt, free movement of enzymes would be even 
more restricted and the time of stewing at 65*C is generally shorter 
than the time for a full mash, so a lot of amylose would be left 
undigested.

>only a small % of the sugars undergo Maillard reactions and become
>unfermentable by this mechanism during kilning, the relatively
>unchanged amylose molecule recrystallize [or perhaps crystallize is
>better - since it's the first fime - No Mort?]

No, I think 'recrystallize' is better since the starch granules are 
already in a crystal structure before gelatinization. The conditions 
for the retrogradation of starch require that the starch molecules be 
gelatinized and then that they be cooled to below the gelatinization 
temperature before they are fully hydrolysed. The slower the cooling 
and the longer time spent at the low temperatures, the more 
retrogradation occurs. Retrogradation is also promoted by relatively 
long chain lengths (>100) and association with lipid molecules, so 
amylose molcules retrograde faster than amylopectin molcules.

Retrogradation of starch is one of the primary mechanisms of bread 
staling and most research has been focused on that area rather than 
brewing. One interesting thing I read about wheat starch is that 
while in its natural state it gelatinizes at ~55*C, after 
retrogradation its gelatinization temperature is 105*C. Whether this 
is the case with barley starch I am not sure, but it could explain 
why it is resistent to enzymes.

>and by an inexplicable mechanism become unfermentable - that is -
>insucceptable to amylase enzymes.

>regardless of malt type - high temp kilnoing => lower fermentability.

The amount of time spent at the high temperature is as important, if 
not more important.

For those interested in reading more about this stuff, I got most of 
the information from these sources:

(1) Gretenhart, K.E. "Specialty Malts." _MBAA Technical Qtly_ 1997 v.34 n.2
pp.102-106.

(2) Jackson, S.W. and J.R. Hudson. " Flavour from Crystal Malt." _J. 
Inst. Brew._ Jan/Feb 1978 v. 84 pp. 34-40.

(3) Manners, D.J. "Starch Degradation During Malting and Mashing." 
_Brewers Digest_ Dec 1974, pp. 56-62.

(4) Palmer, G.H., ed. "Cereal Science and Technology." Aberdeen: 
Aberdeen UP, 1989.

(5) McGregor A.W. "Current State of Research into Barley 
Carbohydrates and Enzymes." in _Proceedings of the Third Aviemore 
Conference on Malting, Brewing & Distilling_ ed. I. Campbell. London: 
IoB, 1990; pp 10-33.

(6) Blenkinsop, P.G. "A Look at Malt Products." in _Proceedings of 
the Third Aviemore Conference on Malting, Brewing & Distilling_. pp. 
179-194.

(7) Bourne, D.T., et al. "Some Factors Influencing the Fermentability 
of Malt." in _Proceedings of the Third Aviemore Conference on 
Malting, Brewing & Distilling_. pp. 309-312.

-- 
Jeff Renner in Ann Arbor, Michigan USA, JeffRenner at comcast.net
"One never knows, do one?"  Fats Waller, American Musician, 1904-1943