9 replies to this topic

[EWW]

I haven't been able to find a good answer with google. Does SO2 reduce/stop the oxidation process? The cider I hit with KMETA looks just like it did from the press, but the natural ferment is significantly darker. Oxidation is the only thing that comes to mind that could cause this color difference. Any insights on what's going on?

[strangebrewer]

You got it. The 2 things it does best is prevent oxidation and inhibit the growth of wild yeast.

[EWW]

You got it. The 2 things it does best is prevent oxidation and inhibit the growth of wild yeast.

Thanks

[strangebrewer]

Thanks

I can provide the mind numbing explanation of what it does on a chemical level if you want but figured I'd spare you.I've noticed a lot of KMETA questions lately. Perhaps it's time for a KMETA FAQ containing important highlights through brain damage.

[EWW]

I can provide the mind numbing explanation of what it does on a chemical level if you want but figured I'd spare you.I've noticed a lot of KMETA questions lately. Perhaps it's time for a KMETA FAQ containing important highlights through brain damage.

I wouldn't complain about too much info.

[strangebrewer]

I wouldn't complain about too much info.

I think I'll start working on a KMETA FAQ but as far as oxidation KMETA primarily does 3 things. First when you smell something that's oxidized that smell is Acetaldehyde. SO2 binds to acetaldehyde creating a stable compound. Next SO2 itself is more readily oxidized then other phenols. So when oxygen is present it is more likely to bind to the SO2 than other flavor and aroma compounds present. Finally SO2 is very good at inhibiting enzymes from functioning. What makes cider or wine brown is the presence of a particular enzyme so the SO2 prevents it from working.

[MyaCullen]

can sulphiting reduce the taste of already oxidized wines? or is it strictly a preventative measure, I assume the latter.

[strangebrewer]

can sulphiting reduce the taste of already oxidized wines? or is it strictly a preventative measure, I assume the latter.

It depends on how oxidized the wine has become. If it's just beginning to oxidize and it's more aroma than flavor and color then you are often able to treat with just KMETA to bind to the acetaldehyde and salvage the wine. If it's further along and the wine is browning then you have to take more drastic measures to remove the flavor and color melanoidins causing the problem. The best product I know of to do this is Polyclar. Polyclar is great on white wines for removing oxidation but is often to much for red wines as it can make an inky red wine salmon pink if you add to much. With a red wine the only real way is to pull samples and do bench trials to figure out how much to add before you start stripping out the desirable tannins and melanoidins. If the wine is at the point of browning in color and smells of vinegar and nail polish remover then the problem is terminal. Obviously the best treatment is prevention.

[EWW]

So if I'm reading this correctly adding a little KMETA before bottling a beer could be a very good thing to treating oxidation issues before they happen as long as you are below the detectable ppm?ETA: why do you know so many interesting things about SO2?

Edited by EWW, 18 October 2010 - 08:51 PM.

[strangebrewer]

So if I'm reading this correctly adding a little KMETA before bottling a beer could be a very good thing to treating oxidation issues before they happen as long as you are below the detectable ppm?ETA: why do you know so many interesting things about SO2?

How KMETA reacts in finished beer is something I don't know. Yes it will act as an oxygen scavenger but I don't know what other compounds are present in finished beer that it could also bind to and potentially strip out. I've never heard of any commercial brewery adding KMETA and they have a major interest in keeping their beer as fresh tasting as possible so I'd think it is either not necessary or has a negative effect.

He reads too many books on winemaking.

What I'm just collecting a library of books to read as bed time stories when I have kids.*peers into crystal ball of the future*Strange Jr: Daddy can we read the one where the K₂SO₄ binds to the acetaldehyde and suppresses the growth of ethyl acetate producing bacteria?Strangebrewer: Of course we can son. Of course we can....