TA & CO2 - some real numbers

[BobF]

Advice is frequently given here to degas wine samples prior to conducting TA tests. Intuitively this makes perfect sense.

While getting ready to do some testing this morning, I decided to do before/after degassing tests to put some real numbers to how important this is.

After mixing and standardizing a fresh batch of NaOH, I tested a Chilean Malbec batch.

The gassy sample tested at 1.1%.

I degassed the next sample by placing it a capped test tube and shaking.

This sample tested at .98%; a .12% difference.

IOW, the gassy sample tested 12.2% higher - a significant difference indeed!

If this wine wasn't so high in acid, say .7%, a .12% contribution from carbonic acid would be even more significant. A .82% result would be 17.1% higher than actual.

 

[BobF]

Damn - I hate it when that happens. I looked at the diff and changed it to .3 mentally.

I'll edit the original post to reflect the real numbers.

Thanx Thig. Recheck me. BTW, I'm dividing the diff by the degassed result since it is presumably the correct result.

 

[winemakingscientist]

Interesting. Thanks for sharing. I wonder if you would have gotten different results if you had pulled a vacuum on the sample rather than just shaking it. I used to work in a research lab, and we'd degas water by pulling a vacuum on it overnight. If you have water just sitting around exposed to the air, the small amount of carbon dioxide that ends up in the water lowers the pH more than you'd think it would.

 

[Pumpkinman]

Bob, Thanks for this info.