Ask Wine Wizard

Organic acid reduction, reusing corks: Wine Wizard



Raising pH the natural way
I am seeking an organic means to raise pH. Any suggestions?
Jim Romano
Carrollton, Texas

The most “organic,” natural way to raise the pH of your wine is to pick the grapes at such a time that you won’t have to do anything to it. I know, I know, that’s a terribly glib answer but as my readers know, I’m all about picking at the right time so your sugar, acid, color, tannin and flavor balance are all in alignment and hey — presto, off you go to make great wine with minimal intervention on the part of the winemaker. Easier said than done, however.    

For those of us not always blessed with the perfect pre-harvest weather, adequately-long growing season or for those of us who must buy off-the-shelf raw material like a kit, we often have to engage in a little bit of what I call “tweaking.” If your raw material isn’t up to your standards or won’t produce the style you’re after, you can certainly (as long as you’re not a commercial winemaker, who must obey the laws of their country and state) add just about anything you want. If you want more alcohol, feel free to augment your fruit wine with honey, grape concentrate or even white table sugar (though I’m not a fan of the latter). Not enough acid? Add some tartaric powder and ferment away. The challenge comes in figuring out what your end goal is (Do you want there to be more tannic grip? Are you trying to produce a minimally-treated wine?) and figuring out how to get there.    

As far as lowering the total acid content of a wine (a.k.a raising pH), there are some ways to accomplish that goal. Whether they are “organic” or not depends on your own definition of the term. The legal definition of organic will depend on where you’re making wine. The laws in the US are very different from that of the E.U., for example. Additionally, many wineries may actually be farming and producing organic wines but don’t choose to register as such; one winery here in Napa doesn’t want to market their wine as “organic” because the US doesn’t allow “organic wine” to contain added sulfites, and there is a long-held stigma against such “organic” wines in some marketplaces. Sulfites naturally occur in wine and more are sometimes added by the winemaker in order to help the wine more gracefully age and develop in the bottle. Adding to the confusion surrounding “organic” wines are the fact that some wine critics want to go beyond a federal “organic” definition and include a halo of purity and “hands off” rules about winemaking, like not adding yeast or only relying on gravity (no pumps allowed) to make wine. I’m not sure whether the goal is to promote more “authentic” or “non-modern” wines (though even the ancient Romans relied on things like presses, sulfur-burning wicks and protein fining) but we do have to ask ourselves where we draw the line. Since I don’t know where you want to draw yours, all I can do is present you with the few options you have to de-acidify your wine and let you pick which method you’re happiest with.

1. Blending
Blending is a great way to tone down or enhance one component or another. I love blending in all of its guises: to punch up the fruit of another wine, to bring up the tannin level of a blend, to add just a hint of residual sugar to a finished wine right before filtering. Blending a wine is like blending a fine perfume (one of my other hobbies, by the way). You’ll never know what just adding 0.5% of Petite Sirah will do to your Cabernet Sauvignon, and that’s half the fun. To “de-acidify” a wine, simply blend in something that’s not very acidic. That is, however, if you have spare wine with the required characteristics sitting around, which, if you do not, leads us to choice # 2.

2. Malolactic fermentation
Isn’t it great to see nature at work? Malolactic fermentation (ML fermentation) is just about the easiest and most natural way to get a wine to lose some of its acidity. The ML fermentation takes place when an organism chews up the malic acid in grape juice or wine and spits out lactic acid, which is half as “acidic” in the grand H+ ion scheme of things. After the malolactic bacteria (which are usually naturally present in the ambient air and may not have to be introduced into the new wine by a winemaker) the wine will be less acidic than it formerly was. Depending on the initial malic acid content, a pH change from 3.40 to 3.55 or a TA shift like 6.5 g/L down to 5.5 g/L is not uncommon (note, it’s hard to correlate pH shift with TA shift unless you do bench trials). The ironic part about ML fermentation, however, is that in order for the ML bacteria (usually Lactobacillus, Lueconostoc oenos, or Oenococcus oeni) to survive and do their business, they need to be in an environment that is over 3.2 pH and preferably higher. If your wine is really acidic, they will be suppressed and unable to survive, no less de-acidify your wine.

3. Adding potassium bicarbonate
Which brings us to option number 3, adding potassium bicarbonate. Approved in many countries for use as a fungicide in organic grape growing and as a processing aide in organic winemaking, potassium bicarbonate (naturally found in the environment from sea water to most plants) can be added to wine in order to de-acidify it. I find that I can achieve a pretty regular drop in titratable acidity (TA) of 1.0 g/L if I add 1.0 g/L potassium bicarbonate. Dissolve the powder directly into your wine, stir, and let settle for 6–8 weeks. By that time you can rack the wine off of any precipitate that has formed and your wine should have lost some acid. You’ll need to know the TA of your wine in order to have an idea of how much potassium bicarbonate to add.        

I hope that the above give you some things to think about and methods to consider when looking for a way to raise the pH of your wine. Your choice will largely depend on your own particular circumstances and goals.

Reusing corks?
Will I ruin my wine by reusing corks removed from other wine bottles
with a corkscrew?
Jim Small
Sultan, Washington

There’s a simple answer to this question — you just might ruin your wine by re-using corks. Corks are challenged already as they are a plug of natural tree bark, full of microbes that are impossible to sterilize away and nooks and crannies within which said microbes like to hide. Corks can carry molds that, when in contact with chlorine molecules, can create the nasty, swampy “corked” aroma 2,4,6-tricholoranisole. Corks also, especially older dried out ones, can leak, allowing wine out or air in. So I have to ask, why would you make an already-imperfect closure even less perfect by putting a hole in it with your corkscrew? As you can tell by my response, my answer would be: don’t do it. I certainly wouldn’t want to risk compromising one of my hard-won bottles of wine by sealing it with an already-unscrewed cork. In real life, I’m a big fan of screw caps. 



UC-Davis graduate and professional winemaker Alison Crowe has been answering hundreds of your winemaking questions as the “Wine Wizard” since 1998. Her Wizard columns have been collected in The Winemaker’s Answer Book which is available at  winemakermagstore.com. 

Do you have a question for her? Send your inquiries to: [email protected].  Unfortunately,  Alison cannot respond personally.