dlp@akgua.UUCP (D.L. Philen [Dan]) (03/26/84)
I sent this by email to wct, but I had trouble talking to
modor!wct, probably because of security reasons. Therefore, I
am also posting it to the net.
Dear W. C. Thompson,
I recently read your article on "net.wines" concerning the
crystals in wine. I have noticed the formation of crystals in
several types of wines and have been most puzzled by them. Where
does the potassium hydrogen tartrate come from, and what causes it
to precipitate? This means that the wine is saturated with KHT. How
does this affect the taste of the wine? It have tasted the crystals
and they are very tasteless. It doesn't take a genius to figure out
they are not sugar or any soluable (sp?) compound like that, and yours
is the first explanation that has ever seemed reasonable to me.
I also notice that not all wines have this problem. Notably,
the Italian wines seems to have a tendency for this, as do
some of the Bulgarian, Yugoslavian, etc. ones. I also seen
wines that not only have crystals on the cork but also have
large crystals in the bottom of the bottle. However, I have never
seen them in any of the California "jug" wines. What is different
in the vinter's process that mades a wines susceptible to throwing
crystals.
As you see, I am most intrigued by these crystals (they are
very beautiful, as crystals go), and I am sure that there are
others who are equally as interested. I would enjoy seeing
more posted to the net on this topic if you have any answers to my
questions. Otherwise email is fine. Stop by Wente and have a
bottle for me.
pulling out the cork
Dan Philen
AT&T Bell Laboratories
akgua!dlpjohnv@ittvax.UUCP (John L. Varanelli) (03/27/84)
Bully Hill Wines (Walter Taylor's reaction to Cocoa-Cola's purchase of Taylor Winery in New York) used to have a short dissertation on the back labels of their red wines which explained the tartrate crystals. As I recall, they were very proud of them. As I recall, inconsistency was a problem at Bully Hill, but the wines are generally good and the winery is quite a story in itself. If you can find a bottle, check the back label, it might well answer some of your questions on the crystals. -- john varanelli (ITT)
norskog@fortune.UUCP (Lance Norskog) (03/27/84)
Former amateur winemaker speaking:
All grapes have small amounts of tartaric acid, and more is created during
the fermentation phases, and some is created by the use of SO2, the vintner's
pesticide. The reason some wines don't have crystals are 1) they are too young,
or 2) the wine is treated so that it won't throw any "yucky-looking" sediment
or crystals. The jug wines you speak of have the hell processed out of them.
Lance C. Norskog
Fortune Systems, 101 Twin Dolphin Drive, Redwood City, CA
{cbosgd,hpda,harpo,sri-unix,amd70,decvax!ihnp4,allegra}!fortune!norskogwct@mordor.UUCP (03/28/84)
Well the first version of this was eaten by an errant Vax--sorry
its taken so long to reply.
A more complete description of the processes producing crystals in wine.
The primary acid found in grapes is tartaric acid. During fermentation
the tartaric acid is mixed with the other constituents of the grapes
including compounds which include potassium. This results in the
following reaction:
Tartaric acid:
H--C(OH)--COOH
|
H--C(OH)--COOH
can combine with potassium to form
di potassium tartrate H--C(OH)--COOK
|
H--C(OH)--COOK
or
potassium hydrogen tartrate
H--C(OH)--COOH
|
H--C(OH)--COOK
Now although the tartaric acid is soluble, di potassium tartrate is not,
and potassium hydrogen tartrate is only partially soluble--the result
is that most of these compounds precipitate out during the fermentation
producing a crystalline crust on the bottom of the barrel during latter
stages of fermentation. The precipitation is temperature dependent,
with lower quantities remaining in the wine as the temperature is lowered.
This explains the absence of crystals in some wines and presence in others.
Modern winemaking in California, and this applies to both the jug and
vintage wines, usually employs a cool fermentation (say 50 to 65 deg f.)
to produce a fresher, fruitier tasting wine. Wines from Italy and many
other European regions are still made in a more traditional style with
fermentation temperatures above 70 deg. Despite some aging at cooler
temperatures, the end result is a wine which has not experienced the cool
temperatures prevalent in American practices, so more of the tartrates
remain in the wine when it is bottled. At this point it is stored in
cooler temperatures (45 to 55 deg) where the crystals form slowly with age.
I suspect that the total absence of crystals in conventional jug wines (and
I'll discount such abominations as Annie Green Springs ....as wine altogether)
is probably related to their storage at very cool temperatures while
awaiting bottling, waiting to be blended, etc. In general, they are processed
much the same as other wines except for the extensive blending of high yield
grapes to obtain consistent results.
Finally, do we have any other amateur winemakers out in netland? A hobby I
can heartily recommend to all wine drinkers.
Bill Thompson
To email correspondents: our modem which was effectively down for three days
is back and email should work, but using 'reply' probably will not work.
The address header through UT-Sally will probably not work for email--try
a route through dual or decwrl as listed below.
--
William C. Thompson III (S-1 Project, Lawrence Livermore National Laboratory)
U.S. Mail: LLNL, S-1 Project, P.O. Box 5503, L-276, Livermore, Ca., 94550
Phone: (415) 422-0758
MILNET: wct@s1-c or s1-a UUCP: ...!decvax!decwrl!mordor!wcttpchmara@wateng.UUCP (Tom Chmara) (03/30/84)
A friend and I hit a few wineries in British Columbia (that's Canada, for you folks frantically consulting your gazetteers). One of the large ones, Calona Wineries by name, has quite an operation involving huge blending tanks >>100,000 gallons (for those people who actually LIKE the taste of warm sweatsocks). This place actually FREEZES their wines (or rather, brings them to -4C, at which point the wine does not freeze but the tartrates settle out) to remove the "wine diamonds" or tartrate crystals. I got the impression that that's why many of the wines sold by large wineries do not throw much in the way of these crystals. Kind of makes you want to cry, don't it? ---tpc--- (Tom Chmara EE @ University of Waterloo, Waterloo, Ontario CANADA)