Ascorbic Acid Super Oxidizer?

[Ufph1]

I've read on a previous thread here that supposedly ascorbic acid by itself can become a super oxidizer instead of an antioxidant. But I've used it by itself and never noticed an issue. And noticed many food items using it as a preservative by itself with no MS. And I know metabisulfate is good for flavor preservation on its own, and that it's used in things such as wine, vinegar etc..... So it seems like using them together is really just saying "the MS works great don't worry about the AA." But I've seen commercial beers with just AA as a preservative. And including listening to people like Charlie bamforth. I've never heard him or anyone give any real scientific talk or evidence of AA alone ruining your beer. So is there any real basis or hard evidence of this being a common problem? Or is this just a theory on a thread here? Because it's the only major place I've seen talk of it.

 

[ajdelange]

When ascorbic acid (or any other reducing agent) does it's job (yield up electrons) it becomes oxidized. It therefore has potential to grab electrons back from something else thereby oxidizing that something else. Here's what Wikipedia has to say

The oxidized forms of ascorbate are relatively unreactive and do not cause cellular damage.

However, being a good electron donor, excess ascorbate in the presence of free metal ions can not only promote but also initiate free radical reactions, thus making it a potentially dangerous pro-oxidative compound in certain metabolic contexts.

Thus under certain circumstances evidently it can backfire on you. Whether those circumstances pertain in your beer or not I don't know. I have also seen in the brewing literature references to this phenomena and to the use of metabite as a backup. I always wondered what the point of using the ascorbate was if one was going to use metabite too.

 

[Ufph1]

When ascorbic acid (or any other reducing agent) does it's job (yield up electrons) it becomes oxidized. It therefore has potential to grab electrons back from something else thereby oxidizing that something else. Here's what Wikipedia has to say



Thus under certain circumstances evidently it can backfire on you. Whether those circumstances pertain in your beer or not I don't know. I have also seen in the brewing literature references to this phenomena and to the use of metabite as a backup. I always wondered what the point of using the ascorbate was if one was going to use metabite too.

Thanks for the input. I am doing two bottlings coming up. One with and one without AA. So we'll see what happens this time.