hist-brewing: Slow Ferment -Reply

Eric.Fouch at steelcase.com Eric.Fouch at steelcase.com
Thu Jul 8 05:51:00 PDT 1999


I tried to send this from home, but I don't think it worked.  Anyway, my intro
to DMS:	

DMS or dimethyl sulfide, is not the product of bacteria.  At any rate, what
bacteria could survive the mash, and the boil, then be in good enough shape to
harm the unfermenting beer?  Methanococcus  jannaschii comes to mind, but it
fixes nitrogen, doesn't make DMS, and lives in steam vents at the ocean floor.
 Wait- never mind, M. jannaschii works best at 2,938 psi, so our beer is safe.

DMS is produced during the boil from a precursor compound, SMM, or S- methyl
thionine, which already exists in malted barely.  Some strains (six row) has
more than others.
Beginners (and veterans) can make beer with to high DMS levels by keeping the
brewpot covered during the boil and during cooling, as DMS is fairly volatile,
and will be boiled off.



Eric Fouch, PDTL
"..but you never know, until you know."
                                                -Dr. Pivo


------------------( Forwarded letter 1 follows )--------------------
Date: Wed, 07 Jul 1999 14:57:50 -0700
To: hist-brewing at pbm.com
From: NTMOORE at SMTPGATE.DPHE.STATE.CO.US
Sender: owner-hist-brewing at rt.com
Subject: Re: hist-brewing: Slow Ferment -Reply

((Sorry to send this to you twice Eric, I hit the wrong button again.))

I do not have the worlds best memory, so someone call me on this if I am
wrong,

DMS is produced by certain bacteria that can live in your wort.  These
bacteria can thrive during either the spaging process if you let the
temperature drop to low, or during the lag time prior to active
fermentation.  To thrive, the bacteria that produce DMS need two
conditions, the proper temperature and the proper pH (I  am sure there
are a million others, but these are the two that effect us).  Now, during
the lag time, the pH will drop, and until a certain pH level is reached these
DMS making beasties will do there work.  Therefore, a common flaw with
new brewers is high DMS levels.  Large, healthy statrers take care of
this problem.

DMS is aldo present in non-boiled malt, this is the second source and one
of the reasons to boil your wort.

Nathi

>>> <Eric.Fouch at steelcase.com> 07/07/99 01:07pm >>>
Could you explain this one?:
And, the biggest reason we try to
shorten the lag with beer is DMS, and the issue there is more with the pH
of the beer wort then competition from yeast.

How is pH linked to DMS?  I suppose as the DMS is boiled off, the pH of
the
wort will change, I'm not sure if it would go up or down....
It has been my understanding that lag time has nothing to do with DMS.
DMS
elimination is done during the boil and rapid cooling.  Lag time, as
mentioned
before, is minimized to minimize the chance of infection.



Eric Fouch, PDTL
"..but you never know, until you know."
                                                -Dr. Pivo


------------------( Forwarded letter 1 follows )--------------------
Date: Wed, 07 Jul 1999 13:28:05 -0700
To: hist-brewing at pbm.com
From: NTMOORE at SMTPGATE.DPHE.STATE.CO.US
Sender: owner-hist-brewing at rt.com
Subject: Re: hist-brewing: Slow Ferment

Wow, I guess I am on a Post-oThon today, sorry guys, but here I go...

>Lowering the temperature will slow the yeast activity. Always. (Well,
>between 32 and 120 degrees F, anyway.)  But this is not necessarily
>a bad thing.  Even lager yeasts ferment more actively at higher
>temperature; however, their products won't be as clean.

This is undisputable and has been proven by several experiments, of
course I dont know if anyone has ever discovered what the ideal temp or
lowest functional temp is and that would be based on yeast strain, but
we know cooling the temperature improves the mead.  Until proven
otherwise, we will call this a FACT.

>We want quick starts to stave off infection.  Fresh must is much
>more susceptible to infection than must once it is active.   Once
>you have a well-established colony of the happy beasties, outsiders
>don't have much chance to cause problems.   We want to eliminate
>the period during which the yeast is just waking up and beginning
>to reproduce.

This also, we can call a FACT, for BEER.  However, I dont think this is all
that big of an issue with mead.  Of course I would not leave an open
must sitting around asking for trouble, but I personally have never
experienced an infection in my mead  And, the biggest reason we try to
shorten the lag with beer is DMS, and the issue there is more with the pH
of the beer wort then competition from yeast.

One example is making fruit wine and ciders with the natural yeasts on
the fruit.  Very slow start, all kinds of exposure to beasties, but the
results are often better then anything you could make with store bought
yeast.  Yes, I am comparing apples and honey combs here, but I think
mead is a lot closer to wine then beer.  And if we used our beer books to
make fruit wine, we would be calling this natural fermentation method a
dumb idea, and missing out on a fun and interesting method.

>Shortening the propagation stage is also desirable for
>production efficiency reasons.  During this phase the yeast
>s using the food (your honey) to make more yeast and CO2
>both of which you discard as by-products) instead of alcohol
>(your mead, do not discard).  If you have a large active
>colony to begin with, you can bypass much of the propagation
>phase and proceed to anaerobic fermentation.

I have not said that I am sure that under pitching the yeast is a
guaranteed way to make better mead.  Hell, I have not even tried it yet, I
currently pitch as much yeast as I can get worked up.  What I am saying
is that we have a couple data points pointing to the fact that it MAY be a
method that makes good mead.  Why?  I do not know.  The sciences
about how yeast works is simple and can be looked up in any of a
handfull of books.  But understanding the chemical reactions is only half
of the art.  Some of it you just have to try.  Maybe the point about
consuming  sugars during propagation has something to do with it, this
would correspond to Als results of ending up with a dryer, smother
mead because you would be consuming sugars w/o producing alcohol.
So maybe by pitching dry yeast w/o a starter you are actually just
producing a lower alcohol mead from the same amount of honey, which
would appeal to many tastes.  This makes since, but it is just a guess.
My point is that someone has told us that they make good meads using
this method, and I do not think we should just pull out our brewing texts
and say "you are wrong"  Anyway, I personally will do a split batch
experiment and report my results in a year or so.  I'll track all sorts of
variables and then have blind tastings.  It will just be one more data point,
but it will help.   I also try to work in my bee pollen experiment with this,
though I have not convinced myself it would be wise to through whole
bees into the must :)

Nathi





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