Winemaking (rec.crafts.winemaking) Discussion of the process, recipes, tips, techniques and general exchange of lore on the process, methods and history of wine making. Includes traditional grape wines, sparkling wines & champagnes.

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Old 02-10-2003, 01:21 PM
Negodki
 
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Default Ascorbic acid as an anti-oxidant?

(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.


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Old 08-10-2003, 12:05 PM
Andrew L Drumm
 
Posts: n/a
Default Ascorbic acid as an anti-oxidant?

"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.


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Old 08-10-2003, 01:10 PM
Negodki
 
Posts: n/a
Default Ascorbic acid as an anti-oxidant?

"Andrew L Drumm" wrote:

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.


Since "the advice given by Presque Isle" is to NOT use ascorbic acid, their
advice is hardly dangerous, and it is your heated response to what was not
stated that is (to use your "polite" phrase) bovine fecal matter. You have
misread their (admittedly poorly-worded and possibly ambiguous) next
sentence, and made a mountain out of an irrelevant molehill, or rather you
have picked a fight where none was offered. At least the other _poster_
(singular) who disagreed (as opposed to "stating the advise was incorrect")
prefaced his remarks with, "Contrary to what Presque Isle SEEMS to imply
above...", and didn't find the need to make a "polite" analogy to fecal
material. Furthermore, since your own statement says this "solution" only
works for 6-12 months before severely deteriorating, it seems that your
advice, not that of Presque Isle, is the more dangerous of the two.

Nevertheless, I shall forward your "polite" remarks to Doug Moorhead, for
his response, and also suggest he rephrase his opinion so that its
misinterpretation won't be so offensive to you.

Meanwhile, I shall stick to SO2 as an anti-oxidant in wine, and leave the
use of ascorbic acid --- with or without SO2 --- to others.




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