Hydrogen peroxide

I would guess that you mean SO2 - not CO2.

What you oxidized was the free SO2. That's how it protects the wine from oxidation. The free SO2 sacrifices itself to consume the oxygen. The product is an insignificant amount of sulfuric acid.

I would guess 40

Peroxide is an even more drastic treatment than aeration. Why don't you try aerating the heck out of one carboy to bring down the SO2, inoculating that with ML, and once it's going "feed" it with the wine from the other carboys? Once the ML gets going, it'll tolerate a little shot of SO2 at a time, and purge it in the leaving gas stream.

Depending on the pH, 50 ppm may not really be that high. If the wine is at pH 3.2 and 50 ppm free, I'd say it's unlikely that it'll ever go ML. OTOH, if the pH is 3.7 or so and 50 ppm free, you probably couldn't _stop_ ML if you wanted to!

Tom S

Trying to lower CO2 from 50 to 20 in order to start MLF in my merlot. I "dribbled" it in a long thread of juice about two feet long from one secondary carboy to another with lots of foam. It only dropped to 40ppm and I suppose I oxidized the hell out of it, if that matters. I would guess 40 is still twice too high. I read that H2O2 works with one ml of 3% peroxide per gallon to lower the CO2 by 10, but I also recall that the problem here is that the peroxide kills the ML germ. I have four more carboys to go so I would certainly appreciate some advice as to how to proceed......

Thanks, Bruce

Tom.....

Yes, I meant SO2... Getting old...

pH was around 3.6 I think. Surprised that there isn't something on the market somewhere that gives accuracy to 0.1. Both pH and TA measurments seem subjective. SO2 titrates seem more accurate once you become practiced at it.

Anyhow, thanks for the advice Tom. I'll try filling the five-gallon carboys half full and shaking the hell out of it. I have an air compressor and could put a hose to the bottom of the carboys. That should do it!

Cheers, Bruce

Not really, if your lab technique is good. Takes practice and a good pH meter. There are relatively inexpensive meters that read to 0.01 pH units.

I assume you mean Titrets. For white wines I prefer a straight Ripper titration, but for reds they're OK. Ripper is really hard to do on reds. I plan to get the apparatus to do vacuum aspiration eventually.

I wouldn't get as drastic as that. Besides, air compressors have a lot of hydrocarbon (oil) in their exhaust unless they're well filtered. Bubbling nitrogen through the wine would be better.

At pH 3.6, I'd say the ML will go with more free SO2 than you think. Just get one carboy going good and use that to start the others. Heavy aeration of all your carboys isn't a good idea.

Tom S