Ask Wine Wizard

pH Adjustments Post-MLF


Dave Rearick — Roswell, Georgia asks,

I harvested my first crop of Chardonel and Norton this year. Both had pH in the 4.0-4.24 range with total acidity (TA) around 8. After malolactic fermentation, my TAs were around 7, but the pH still stayed high. I’ve heavily sulfited to protect the wine, but I’m curious if you feel I should lower the pH prior to aging by adding tartaric acid, or just follow my SO2 and maybe adjust after six to nine months?

Absolutely, I would lower your pH prior to aging. No matter how high the TA is, if you’ve got a high pH as well, you are putting your wines at risk for premature oxidation and, most critically, are providing an environment that favors the growth of spoilage organisms. Bacteria enjoy higher pH environments, even with a relatively high TA. Exactly how much acid you will have to add is difficult to calculate because it depends on the buffering capacity of each individual wine. I would recommend adding 1 g/L, re-measuring your pH then re-tasting and adding more as you like, doing it incrementally — maybe at 0.3 g/L after that, or after seeing what 1 g/L got you. You want to get the acid reading into a safer range, but you certainly don’t want to overshoot. I would aim to get your pH down to at least 3.75 because at higher pHs, SO2 additions are less effective against microbes and oxidation.
Response by Alison Crowe.