My merlot is in secondary fermentation. What is the procedure for measuring TA now that there is alcohol and SO2 present? I have the general idea of boiling the wine and refilling with water to the original wine level. What size sample is best? How long would I boil it? Heavy boil or less that 212 degrees? Thanks for any tips on this one......
A few seconds is enough. As soon as it boils you have released the CO2, which is all that matters.
Regards, Joe
Bruce wrote "What is the procedure for measuring TA now that there is alcohol and SO2 present? I have the general idea of boiling the wine and refilling with water to the original wine level. What size sample is best? How long would I boil it? Heavy boil or less that 212 degrees? Thanks for any tips on this one"
Bruce - Be careful what type water you add to replace water lost during the boil. Example - my local KC tap water pH is around 9. Water with this much alkalinity will surely neutralize some acid in your sample. Best to use distilled or reverse osmosis water for all of your TA titrations and to replace boil-off water. Sample size - large enough so you can easily measure your test samples. Also, use a calibrated beaker or cup so you can tell the original volume. Boil time - I don't know for sure. It wouldn't be long. I just put mine in the microwave and heat till I see bubbles coming off.
Bill Frazier Olathe, Kansas
Just do what it says on the test pack, 5 ml generally is used. Boil or whatever to get the CO2 out, boiling doesn't evaporate the acids which you are neutralizing, but more than bringing to the boil is unnecessary. You can fill up with as much water as you like, as the total amount of acid only depends on the original sample of 5 ml wine. It's often diluted to 50 ml, which is practical if you're looking for colour changes. Alcohol or SO2 don't have influence on this measurement.
pH of the water for dilution has minimal influence on TA measurement (say less than 0.01%TA), so don't bother with the next advice which is I'm sure given with the best intentions:
Great help... many thanks guys......
Rene wrote "Just do what it says on the test pack, 5 ml generally is used. Boil or whatever to get the CO2 out, boiling doesn't evaporate the acids which you are neutralizing, but more than bringing to the boil is unnecessary. You can fill up with as much water as you like, as the total amount of acid only depends on the original sample of 5 ml wine."
Rene-If you heat or boil you wine sample before dilution you very well may drive off enough volume to change the acid concentration. Been there, done that. If you dilute your 5 ml wine sample before heating or boiling you may be OK but I usually heat my wine before measuring the sample for testing.
"pH of the water for dilution has minimal influence on TA measurement (say less than 0.01%TA), so don't bother with the next advice which is I'm sure given with the best intentions:"
Rene - I don't know where you live but here in the Kansas City area our tap water pH is usually around 9 and the water is chuck full of minerals. Just the other night, at wine club meeting, we were discussing this very question (what difference does water make in TA measurement). A Vidal wine was tested, using distilled water for sample dilution. Result 0.63 %TA. The test was repeated using our tap water for dilution. Result 0.47 %TA. Quite a dramatic differenct IMO. Perhaps for people whose local water is very soft it might not make as much difference but in our area it's best to use distilled or RO water.
Bill Frazier Olathe, Kansas
Hi: Heat to boiling then cool it down quickly and titrate.
If you want to get CO2 out of a sample quickly, buy one of the vacuum wine savers designed to preserve a bottle of wine after it is opened. They have a pump that pulls a vacuum on a bottle of wine to remove O2 from the headspace. You can put your sample in a 375ml bottle and pull a vacuum using the pump. The wine will give up the dissolved CO2 pretty easily under these conditions and no heating is involved.
CHEERS!
Thank you for the great idea!
Bill,
That's absolutely amazing! I would call it 'buffered water' I wonder if you could drink it safely :-) Rene.
Overly complicated suggestions. I have worked in the lab at Ferrari Carano Winery (100,000 cases) and the answer there is simple.
Heat the 5 ml sample for about 9 to 10 seconds in the microwave, add distilled water to dilute so you can easily see the endpoint, then titrate.
Bob B
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