"Negodki" > wrote in message
...
> > (evilpaul13) wrote:
> > What is the general consensus on an addition of vitamin C to act as a
> > preservative in wine? (I'm not talking about replacing sulfur dioxide,
> > just complementing it.)
>
> > "Negodki" > wrote:
> > According to Presque Isle, "Results are inconsistent and we can't
> > recommend it. It is often even less effective if used in combination
> > with SO2. Its best use is in the treatment of wine that has had some
> > H2S progress to disulfides. Using .25 grams per gallon will cause
> > disulfides to revert back to mercaptans, albeit slowly, which can then
> > be dealt with using copper or boecksin."
>
> "Andrew L Drumm" > wrote:
> > To agree with others - this advice regarding combination with SO2 is
> > absolute BS. ALWAYS use SO2 with ascorbic. Ascorbic works fine for about
6
> > months to a year, then it's bad. If your wine will be drunk in this
> period,
> > then ascorbic does very well as an antioxidant, probably better than
SO2.
> > After this, things go very bad very fast, as oxidation of ascorbic
> produces
> > peroxide, which also scavenges your SO2, so oxidation of your wine
> > accelerates! I've never heard of it used to fix disulphides - it might
> work,
> > but your best approach is to knock any H2S on the head with copper
before
> it
> > has a chance to go to disulphide.
>
> It's bad form to describe a dissenting opinion as "BS", absolute or
> otherwise. Presque Isle is a reputable supplier of winemaking equipment
who
> have been in business since 1964. They are also a Pennsylvania bonded
winery
> with considerable experience. Their owners and staff have impressive
> credentials and a vast array of knowledge and experience. I respect and
> value their opinion as much as any member of this newsgroup.
>
> You may have had different experience than Presque Isle with ascorbic
acid,
> and I'm equally interested in hearing your experiences and opinion. It's
> also possible the PI is in error in this instance, or that there is a
> typographical error or hiatus in the text. But denigrating another source,
> especially a respected source, is unnecessary and offensive.
>
> Something which "works fine for about 6 months to a year, then ...
produces
> peroxide, which also scavenges your SO2, so oxidation of your wine
> accelerates" doesn't sound like something I would wish to use. Even if I
> _intended_ to drink the wine within that short time period, the thought of
> it being ruined if I did not is quite unattractive.
>
> Obviously it is preferable to eliminate an H2S problem before it
progresses
> to disulphide, and no one has recommended that one wait until this stage.
> But sometimes the best efforts of mice and men fail, and then a solution
> must be found. PI has suggested one, and I have quoted them. You are free
to
> ignore their advice.
>
> One could make a similar statement about your (abbreviated) copper
solution,
> e.g. "your best approach is to avoid H2S problems in the first place" ---
> good advice, but hardly helpful to someone who has not done so.
>
>
The advice given by Presque Isle is highly dangerous, and people listening
to it run the risk of ruining their wine, therefore I will stand by my
statement that their advice is absolute BS (and where I come from, that's
being polite). The point that ascorbic acid needs SO2 was made repeatedly
when I was studying oenology, and standard industry texts also support this
view. You will also have noticed that I was not the only one stating that
this advice was incorrect.
For references, see:
Ribereau-Gayon,P., et al, "Handbook of Enology" (2000) Wiley
Section 9.5.1 "ascorbic acid should only be used in wines containing a
sufficient concentration of free sulfur dioxide, available for the
elimination of the hydrogen peroxide formed in the course of oxidations"
9.5.4 "Ascorbic acid permits a better conservation of wine freshness and
fruitiness-especially in certain types of dry or sparkling white wines"
Ough, C.S., "Winemaking Basics" (1992) Haworth Press
p.281, quoting Rankine: "He suggests that as long as 15-35mg/L of free SO2
is present, its [ascorbic acid's] use is satisfactory."
Rankine, in his own winemaking book (which is at work, so I can't quote him
verbatim or give ), also says much the same.
In Australia, the use of ascorbic acid, while becoming less common, is
certainly a commercially acceptable practice for the production of fresh,
fruit-driven wines that are to be consumed within one year of bottling.
If you are thinking of following Presque Isle's advice, I would ask them
where they got their information from, and consult the sources personally,
rather than relying on their interpretation. It conflicts with every single
piece of advice I have seen concerning the use of ascorbic acid.