Took a sample of about one hundred Syrah berries from my vineyard. Ran some tests and results seemed abnormal. Brix: 23; pH 3.13; TA 9.65. This low pH, high TA is not what I have seen in the past and got me wondering about my pH meter and my NaOH solution. I calibrate the pH meter frequently and seldom have issues with it. The NaOH solution(0.0667N) was fresh as I had just made it the day of the testing. I was wondering about how you test a solution to make sure it's right. In the past I've made the error of adding a weighed chemical to 1 liter of distilled water rather than dissolving the chemical in 500 mL and then topping off to 1 liter. That's not the case here. I've seen on another website a way to test the NaOH solution by making a 5g/l solution of tartaric acid and titrating with a .2N solution of NaOH. With a 15mL sample of the tartaric acid solution, a fresh solution of .2N NaOH will bring the pH to 8.2 by titrating exactly 5 mL. Chemistry is not my strong suit but it seemed logical that the results would be different using a 0.0667N solution. With a 5mL sample of the tartaric acid solution, titrating 5mL of 0.0667 brought the pH to 8.2. Is this just a coincidence or does it follow that the weaker solution of 0.0667 NaOH with a corresponding smaller sample of the tartaric acid solution is the right way to test the NaOH solution? And is 5 mL of 0.0667N NaOH the right number to titrate a 5g/L of tartaric acid solution to a pH of 8.2? Thanks for any help. Next I got to figure out how to deal with a TA of 9.65 if that is for real!
Low pH, high TA must
- Thread starter jestar
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Would you mind elaborating? Is it something specific to the syrah grape?
My response to Wade E is that is why I'm questioning my testing. I have never had any of my wines with a TA that high and something is wrong somewhere along the line. Just trying to figure out where. To answer your question, Syrah is not any different. The high TA may indicate unripe berries but with a Brix of 23, the TA shouldn't be that high.
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A white varietal in Southern Ontario is one thing and 9.65 g/L might even be expected, but a red varietal in a vineyard 25 miles from Lodi, CA is another thing altogether. In previous years the TA has been between 6.5 and 7.5 g/L depending upon varietal. This area has been quite a bit cooler than normal and the growing season has been about 2 to 3 weeks behind schedule from the git go. I'm wondering if that has something to do with it.
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