Issue link: http://winesandvines.uberflip.com/i/62409
Postmodern Winemaking CL ARK SMITH natural, and we want to give it to them. But above all, they want tasty wines and won't settle for less. Fortunately, today's winemaker is blessed with a broad and rapidly expand- ing array of choices for bringing wines into acid balance, and a number of mem- brane techniques have recently been add- ed to the dizzying array of tools. Choos- ing among them requires a firm grasp of acid-base chemistry. unlike their eastern counterparts, West Coast growers are not used to lowering acidity. Adjusting Acidity With Membranes C alifornia has just survived its most challenging vintage in decades—almost as difficult as a typical vintage anywhere else. Until recently, acid adjustment in West Coast wines consisted of deciding whether to add to the must one gram per liter of tartaric or two. Even our high pH/high TA (titratable acidity) challenges were mostly high potassium problems that were overcome by the nerve-wracking but effective practice of lowering pH with even more massive tartaric bumps, followed by precipitation of a blizzard of cream of tartar. The cool, rainy vintages of 2010 and 2011 have resulted in a comic assortment of pH and TA conditions that have sent winemakers back to their schoolbooks to relearn the basics. When pHs wander into the 4s during a cool, long season, some- times the culprit is high malic (under- ripeness), sometimes high potassium (K+ ) (over-ripeness). Treatments differ entirely. In 2011, it wasn't unheard of to get both conditions in the same must. In this we have joined the ranks of our Eastern winemaker brethren now labor- ing for fully half the wineries in North America, and for whom expertise in this field is their chief employment qualifi- cation in the chilly northern climes of the Midwest. The front office may sing love songs of non-intervention, but every winemaker knows that a dry white wine with 12 g/L (grams/liter) or a brown, tired, dried-up Pinot will fight an uphill battle to please the most luddite consumer. Sure, they want The basics about acids An acid is just a dissolved substance that can slough off a hydrogen ion (H+), really just a proton. Because the acids in wine are "weak," some portion of the acidic hydrogen ions (protons) remains bound to them. To figure when to pull the trigger on harvesting a block, winemakers look at both TA and pH. A glance at this season's must chemistry will convince the most un- schooled winemaker that pH and TA are not very closely related. Both measure acidity (high TAs and low pHs denote lots of acidity), but TA is the sour taste, while pH is the amount of free, dissociated protons controlling the wine's chemistry and microbiology. TA is like the cops on the payroll, while pH is like the Highlights • Climate change and the conquering of new cold-climate regions demand that winemakers get smarter about acidity. • The author reviews standard ways to control pH and TA, and he explores the potential of new membrane technologies to do the same. • Choosing among options requires a firm grasp of the technical functionality, cost benefits and legal factors involved in each selection. Wines & Vines JAnUARY 2012 137 HANS WALTER-PETERSON