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Ascorbic acid as an anti-oxidant?
"Negodki" > wrote in message
m... > (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.) > > 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." 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. |
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Ascorbic acid as an anti-oxidant?
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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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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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