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TIM PATTERSON Inquiring Winemaker Why Winemakers Don't Dare Touch pH T he marketplace for wine technologies, additives and services features its fair share of "solutions" to problems winemakers don't really have. If you believe all the brochures, most every grape is nutrient-deficient and color-shy, sorely in need of enzymatic assistance or vinous mustard plasters, and headed for a final alcohol level that could always be made better with a quick journey through reverse osmosis. But this month's sermon is about a different mismatch: a problem that truly does exist, and for which solutions demonstrably work—but hardly anyone bothers to use them. That problem is high pH, which is rampant in California and hardly unheard of elsewhere in the country. I'm thinking here not so much of pH a tenth of a point higher than target, easily fixed with a soupçon of tartaric acid, but crazy high pH, up over 4.0—pH so elevated that sulfur additions become guesswork and the acid boost needed to tame it thoroughly would yield wine that tastes like lemon juice. If I have had this problem more than once in my modest garage winemaking, I'll bet you have, too. When a wine has too much VA, people fix it. Too much acid, people fix it. Too much sugar or alcohol, people fix it. How come more winemakers don't fix their pH levels? Growers routinely adjust the pH of the soils of entire vineyards, and wineries routinely tweak the pH of their wastewater. Why not pay the same attention to a tank full of wine? A pH refresher pH is arguably the single-most-important analytical number in wine chemistry. pH levels set the context for almost every kind of chemical or microbial activity from fermentation through bottle aging; pH affects 32 W in es & V i ne s D EC E M b e r 20 13 the potency of sulfur dioxide, the success of malolactic fermentation, the solubility of tartrates, the formation of esters, the rate of anthocyanin polymerization and the expression of color as well as the vulnerability of wine to spoilage organisms. You can't just add or subtract a quart of pH the way you can add sugar or water or acid or oak chips. But despite being a big deal, pH remains a little mysterious—even to veteran winemakers—in part because it isn't directly accessible and adjustable. You can't just add or subtract a quart of pH the way you can add sugar or water or acid or oak chips. The best you can do is try to influence pH by manipulating something else. In really Highlights • igh pH is a chronic problem in warmH weather winemaking, but few winemakers take advantage of technologies that can alter pH dramatically. • owering pH through acid additions only L goes so far, and it does not address high-potassium wines. • urprisingly, providers with equipment S that can directly address pH report very little business on that service. cool climates, that may mean de-acidification to get pH up to a malo-friendly level; in California, it almost always means coaxing pH down toward something recognized in winemaking textbooks. That in turn means tossing in various amounts of tartaric acid, which can work just fine for small pH glitches, making the wine taste more balanced in the process. It may be that the constant resort to acid additions as a means of fixing pH makes the tartaric bag seem like the only tool in the box. But it's not, and in any case, it only goes so far. Wines with astronomical pH or a high buffering capacity—the presence of certain compounds that tend to keep pH right where it is—can require so much added acid the wine becomes undrinkable. Yes, adding acid always lowers pH, and the rule of thumb that adding 1 gram of tartaric per liter of wine will drop the pH by 0.1 is worth remembering. But does that always work out as planned? No. Acidity and pH are related, but not in a simple inverse dance, because they are measures of different things. The full story is in the accompanying sidebar (see page 34), but here's the executive summary: Total acidity is a calculated expression of organic acid concentration based on measuring negative electrical charges. Titratable acidity (TA) is what you get with a particular test using a particular pH endpoint; it is always less than the total acidity, but ever so much easier to discern. pH, on the other hand, rests on measuring positively charged ions, including lots of things—primarily potassium—that have nothing to do with organic acids. That gets us to the Achilles' heel of tartaric additions as a means of lowering pH: They don't do much of anything about the concentration of pesky potassium. A major boost in titratable (and tasteable) acidity may yield only a trivial drop in pH, and thus not make a dent in flattened flavor and color and microbial instability. Faced with a wine that misbehaves in this way, winemakers can just throw sulfur dioxide at it, blend in something more colorful or hope folks drink the wine young. High pH does not guarantee disaster or even unpleasantness; it just raises the odds. Alternatively, winemakers can use a range of