SO2 in Barrels

sdelli · Apr 16, 2017

Been making wine for few years now and primarily from fresh grapes. I play with juice and a kit from time to time but the main wine I drink is from CA grapes. I have 7 barrels n my wine cellar from all sizes and age ranging from 6 gallons to 30 gallons. Only two of the barrels are new this past season. The he rest have seen some wine. This past season like all the rest I completed mlf then racked to barrels taking out previous years. Added about 1 gram of kmeta per gallon of wine. That was right before xmas..... I just checked all the barrels yesterday and none really need any kmeta added... After almost 4 months I have added none! Yes gone down a little but very little... Yes, I used brand new titrants and calibrated my sc-300 twice... I am not complaining but never had this before! Win smells and taste very clean. Did I just get a good batch of grapes? I am very clean and cautious of air so no fights there but still very surprising. Anyone ever experience this?

stickman · Apr 16, 2017

A gram per gallon is over 100ppm so2, I would say you shouldn't need any more.

skeenatron · Apr 16, 2017

I've never seen while sit in barrel for 4 months and not drop in free SO2, only in a closed vessel like kegs and bottles have I seen that. That being said, if you have your barrels in an environment where there wouldn't be much evaporation of wine from the barrel, and in turn don't get a lot of oxygen exchange into the barrel, I could see very small levels of free SO2 binding happening. Perhaps this is what's going on in your situation. I would probably bet on it being something else though, like perhaps your free SO2 level readings from 4 months ago were actually lower than they really were. Maybe you accidentally added a little more SO2 than you thought you had 4 months ago.

Either way, your wine sitting in barrel that long and not going down at all? That is in my opinion the least likely scenario. If it were, you would have probably seen zero head space in the barrel when you opened it to pull your sample. I would imagine you just had a bad reading or measurement somewhere and if you double checked your numbers this time around, looks like you are good to go. I've done it myself.

sdelli · Apr 16, 2017

I am definitely adding a good amount of wine across the 7 barrels every 10 days. More on the small ones then the larger ones.... I am going to probably lean on what stickman stated that a gram a gallon might of been heavy... Should of been closer to 1/2 gram per gallon.... Well, at least I don't have to add any for awhile.

Johnd · Apr 16, 2017

sdelli said:
I am definitely adding a good amount of wine across the 7 barrels every 10 days. More on the small ones then the larger ones.... I am going to probably lean on what stickman stated that a gram a gallon might of been heavy... Should of been closer to 1/2 gram per gallon.... Well, at least I don't have to add any for awhile.

Consider using Fermcalc or some other calculator or chart to help you dial in your additions. 1 gram per gallon, with a wine pH of 3.6, and 1.81 equilibrium constant, gives you over 150 ppm free SO2. Regular toppings to reduce air space has helped preserve your levels as well.

It only takes .21 grams per gallon to get to .5 molecular level, 32 ppm, which is proper for a red wine of pH 3.6. You didn't state your wines pH, just taking a stab at it........hope this helps.

4score · Apr 16, 2017

I always take the number of gallons of wine times the PPM goal times 0.00664 and this will tell you the number of grams of SO2 to add.

So, 1 gallon wine times 32 PPM = 32. 32 times .00664 = 0.21 grams of SO2 .

sdelli · Apr 16, 2017

Believe me... I have charts and calculations to get the amount of kmeta added per ph level... I just made the initial addition after mlf to aggressive. I do not test so2 coming out of mlf. Only test there after... Probably got too aggressive on my initial dosage. At least that is what makes the most sense...