hist-brewing: malic acid vs. acetaldehyde/"stale"/seeking publications
brewinfo at xnet.com
Wed Apr 5 16:56:21 PDT 2000
Angus <angus at iamawitch.com> wrote:
>My guess is that the lager yeast will produce high levels of maleic acid
>which gives the beer a strong flavour of green apples. How strong is hard
>to say, it depends on how active the yeasts are relative to each other. I
>fermented a lager on my balcony in mid december and had to bring it in
>when the temp dropped to -9C and let it ferment the last sugar indoors.
>Indoors fermentation began at 1.018 with a FG of 1.010.
>If my memory serves me right OG for the batch was somewhere around
>1.040-45. The final product tasted somewhat like a blend of apple cider
>and lager beer.
>It took some 200g/l of raspberries to mask the apple taste and even then
>it was noted through the raspberry taste.
I believe that Jeff and Nate are right that it is acetaldehyde and not
malic acid that lends the green apple flavour. Personally, I have found
(based upon years of judging homebrew competitions) that I have an average
sensitivity to acetaldehyde. I (unlike Jeff) sense a moderate amount of
it in Budweiser and do not (unlike Nate) sense it in Miller Genuine Draft.
The reason that Budweiser has more than most beers is because Bud yeast
is very flocculant. The "beechwood aging" they advertise would be
unnecessary if they used a different yeast. The "beechwood aging" consists
of stacking hundreds of beechwood "chips" (their word, not mine... actually
they are a few inches wide and a foot or two long and a fraction of an
inch thick) in the bottom of a horizontal stainless steel tank and pumping
active beer in there. The yeast settles on the sanitised "chips" and this
exposes a lot more yeast to the beer than if all the yeast simply settled
to the bottom of the tank. With the increased surface area, they can age
the beer a shorter time. If you age long enough, the yeast re-absorb the
acetaldehyde they created earlier and the level drops below the taste
threshold. A-B ages it less than "long enough" and so some of the
acetaldehyde remains in the beer. If lagers are rushed (i.e. under-lagered)
then some acetaldehyde does remain... this is why it is usually associated
with lager yeasts.
I don't recall whether ale yeast produces less acetaldehyde, but I do know
that at ale fermentation temperatures, the acetaldehyde does get reabsorbed
Under-oxygenation and poor yeast nutrition increase acetaldehyde production.
I have long theorised that the "cidery" flavour attributed to excessive sugar
additions is due to insufficient nutrients. There is a lot of sucrose added
to Westmalle Tripel and yet no cidery aroma or flavour. On the other hand
if you take 3.3 pounds of extract and add 5 pounds of sugar, you are most
definitely making beer from a nutrient-deficient wort.
>The word 'stale' is used much in much old records as
>ale that has aged beyond paltability. I made a oat
>ale and it was great at 5 days old, palatable at 7 days,
>ok but nasty at 9 and it did have a stale taste at 10 days.
I believe that it is in the book "Porter" published by Brewer's
Publications (Association of Brewers) that the author explains
that "stale" doesn't mean "bad" but rather "aged." At least one
recipe for a blend of beers called "three threads" includes
a certain amount of "stale" beer (which was the expensive one!)
and two cheaper beers. I don't believe that this is the definition
used here, however, because it was only something like four days
and in the case of three threads the stale beer was many months
(perhaps even more than a year) old.
In any event, I'm pretty sure it didn't mean "unpalateable."
Another source that I believe mentions stale is the "The London
and Country Brewer" (5th edition, published in 1744). If anyone
has access to this excellent publication (or any of the other
editions, as I believe it to be a compendium of articles... different
in each edition), I would be willing to pay you to copy it for me.
Another publication I've been looking for is "The Brewer's Assistant"
by G. Sleigh (Bath, 1815). Again, I'd be willing to pay for a copy
of this book.
You see... although I'm somewhat interested in all historical
brewing, I'm *primarily* interested in 18th and 19th century brewing.
Al Korzonas, Lockport, Illinois, USA
korz at brewinfo.org
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