Ascorbic acid sources

That should work. I beleive it has sugar in it so do not add it prior to bottling with stabilizing it first.

Ascorbic acid (vitamin C) really only protects against oxidation for a very short time. You might want to add a small amount just before racking in conjunction with meta bisulfite, or if you're aerating wine to remove a hydrogen sulfide smell, but generally ascorbic acid isn't a good way to protect against oxidation. Since ascorbic acid works not by protecting from oxidation itself but by increasing the efficiency of other antioxidants (like meta bisulfite), in cases where you don't have enough bisulfite in the wine, ascorbic acid may actually increase the rate of the wine's oxidation.

A cheap and easily available source for ascorbic acid is vitamin C tablets, which you can crush in a spoon. I'd stay away from the fresh fruit unless (such as lemons) unless they're a primary ingredient for the wine you want to make (and I particuarly won't introduce them into a vinifera-grape wine).

Jon [Check out my winemaking homepage

I have added Fruit Fresh to my must before I ferment. Can't find it anymore. Now I use crystaline Vit C from Trader Joe's -- got a big botlle of that, should last me a long time. Most people prefer to add acid in the form of acid mix. The acidity of Vitamin C seems to fade during fermentation, I'm guessing the yeast are eating it, which is why I like to use it early in the fermentation. If you search the web, you'll find some references to using ascorbic acid to prevent oxidation.

Now I use crystaline Vit C from Trader Joe's -- got a big

how much do you add per gallon?

I don't understand why you wish to add ascorbic acid to a healthy wine. My understanding is that it _promotes_ oxidation, rather than prevents it.

The only reason I know of for adding ascorbic acid to wine is if you have a dimercaptan problem (rubber boot smell). It breaks the dimercaptan into monomercaptan, and that can be treated with copper sulfate, usually followed by activated charcoal.

Tom S

I was sure that ascorbic acid was an anti-oxidant. No?

no, ascorbic is a reducing agent. It can function a lot like metabisulfite, but it is weaker. I guess people might want to use it if they are sulfite sensitive.

Nevertheless, see the Wikipaedia entry for Vitamin C, where it is described as an anti-oxidant.

some reaction happens and it actually promotes oxidation as Tom said. Because of that it should never be used instead of sulfite. The use I've heard is adding some while bottling (and maybe racking) and reducing the amount of sulfite used at the same time. It sounded like too much hassle with doubtful gain, but it might make sense for people who are sensitive to suliftes.

Pp

I was not saying "no" to you sam, but to Tom.

Reduction is the opposite of oxidation.

Being an anti-oxidant is often the thing as being a reducing agent. Oxidation is when an atom loses electrons (and its oxidation number increases. So if you take iron and let it rust it goes like this 2 Fe

• O2 -> 2 FeO the iron lost two of its electrons and has oxidized to the Fe2+ state. Now if you heat that rust with hydrogen gas H2 you can REDUCE the oxidation number of the iron back to 0 and you get the iron metal back and water FeO + H2 -> Fe + H2O. That is reduction.

Ok, now the difference between being an anti-oxidant and being a reducing agent. An anti-oxidant is a special class of reducing agents that can accept electrons from free radicals and reactive oxygen species. Those chemicals do not chemically react with things in such a nice chela manner as above with the rust. Instead they tent to give things extra electrons that they do not need and damage them. But they do not exactally chemically combine with those things. So anti-oxidants are reducing agents, but reducing agents may not be anti-oxidants.

The reason I use reduction instead of anti-oxidant is becasue that oxidation in wine is not always due to free radicals or reactive oxygen species. Instead it is more like the "rust" example. That is oxygen (and other stuff) is chemically reacting with wine components and changing their character. The wine is "rusting"

I dunno, it is a subtle difference. To a chemist like me it is a big difference.....but to all of you it is probabally a forgettable one.

Snipped...

May well be a reducing agent, but numerous experiments using ascorbic acid in white wines have shown that it actually promotes the browning effect in whote wines. The ascorbic acid oxidizes and forms dehyrdroascorbc acid and hydrogen peroxide. We definetly don't want hydrogen peroxide in our wine.

It was also shown to increase the consumption of sulfur dioxide in the wine so if ascorbic acid is used, you need to increase the amount of SO2, not decrease it.

The conclusions I usually see are that while ascorbic acid can have a short term benefit in preventing oxidation, once the ascorbic acid is oxidized, is causes more harm than good. Using just SO2 is a better method of protecting your wine unless you need the ascorbic acid for other reasons (like a dimercaptan problem).

Andy

So if you take iron and let it rust it goes like this 2 Fe

Well now I understand it.

I had that back in chemistry and i think when i was told that oxidation takes electrons away and reduction didn't, that made no sense so I made no effort to understand it.

Been one of my lifelong problems, if it doesn't make sense on the surface, I skip it.

So, if I get some hydrogen gas I can turn a rusty old pinball part back into its former self?? This I wanna see.

Those chemicals do not chemically react with things in such a

so is chelation therapy any good?

The rust would go back to being iron, though the surface will never be as smooth as before.

With wine it's not so simple... the heat would change the flavor big time; nevva be anything like its former self.