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High-pH Wine

TroubleShooting

Hunter Nolen — New Braunfels, Texas asks,
Q

Thanks again for your help in saving my high-sugar Viognier a couple of years ago. It is all gone now! I grow Syrah, Tempranillo, and Mourvèdre. In the Texas Hill Country the grapes “cry uncle” around the third week of July and I have to harvest or they will abruptly collapse in the relentless 100 °F (38 °C)+ heat. Because of the abruptness of collapse, I have learned to pick early rather than late because early means usable grapes and late means mush! I therefore end up picking on the third weekend in July when I can generally count on little rot, decent maturity, and available family and friends to help.

Also, due to the daytime heat and little relief through the night, I generally wind up with high pH. This year my pH came in at what I consider quite acidic for my vineyard (3.4), while my sugar was light (about 21 °Brix). I therefore chaptalized to about 24 °Brix before pitching my yeast. After fermentation, my pH had risen to right around 3.7, and I get a little nervous about long-term stability above 3.65. My inclination has always been to acidulate to around 3.65, which makes me more comfortable and usually does not tarten up the wine too terribly much.

I am generally inclined to conduct MLF on my red wine even though the pH is on the high side. I like to know my wine is stable for the long run, and generally favor the idea of converting my malic acid to lactic acid for flavor and mouthfeel reasons. But, I have seen some literature that suggests foregoing MLF on high-pH wines. This year I have done no acidulation yet and started my MLF culture going on the pH 3.7 wine. Finally, after MLF this year I fully expect my pH to be up around 3.8.

OK, enough of the chatter. My questions below in orange

A
QIn the above situation, what do you suggest I do? Do you agree that I should conduct MLF on my wines considering their high-pH characteristics? AFirst off, glad your Viognier got better! That’s awesome you’re doing both reds and whites, it’s fun to try a lot of different kinds of wines. Well, I hear you about heat — I grow some grapes in Paso Robles region of California and we definitely have high pH problems as it gets so hot. For your Texan reds, even though the pH is creeping up at 3.7 post-primary fermentation, I still encourage MLF in this situation because aging red wines are always a risk for in-barrel or in-bottle MLF, both of which can cause off aromas and flavors and can ruin your wine. QWhat is your absolute top-end pH that you personally will not go above in a finished red wine? AI don’t like to go above 3.85 at bottling, though that means you need to really have great sanitation, no headspace, and minimize oxygen exposure. It’s also not a safe pH to be
Response by Alison Crowe.