Ascorbic acid as an anti-oxidant?

There is another, more recommended use for ascorbic. Recent research out of Germany and the New York State Experiment Station at Geneva (Cornell's enology group) indicates that 100 ppm of ascorbic can help (but won't always help!) delay the onset of ATA (atypical aging).

I'm not sure how prevalent ATA is elsewhere, but we're surely seeing it here in NY, and I guess they are in Germany as well. Testing for ATA on whites is now part of my general QC routine (heat stability, cold stability, general wine chemistry, etc.)

Contrary to what Presque Isle seems to imply above, NEVER add ascrobic to a wine without SO2!! It's a really strong oxidant (generates H2O2) when used without SO2.

Dave

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I shoulda looked before asking. Still interested in what you're experiencing/ doing, but found some nice info here:

I don't know of anyone in this area that has noticed the problem, but generally we're not considered a cool vit climate.

clyde

How do you test for ATA?

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From Cornell's document, they heat two samples at 40C for two days. One of the samples is treated with 150 mg/L of Ascorbic Acid, the other one is left untreated (control). If any difference is noticed in the organoleptic qualities, then ATA is likely to develop.

clyde

Hi Clyde,

The test is as you describe it in your other post.

And ATA is really weird. It seems to hit some bottles and not others, and can ge generally described as premature and unattractive aging. The wiwne takes on weird flavors (dirty dishrag, bubblegum, bad hydbrid character in vinifera), and does so quickly, within a year of bottling.

Dave

**************************************************************************** Dave Breeden snipped-for-privacy@lightlink.com

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.

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.

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.