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WINEMAKING els present in non-sparkling wines, Bruce Zoecklein of Virginia Tech thinks it isn't likely to have any significant effect in re- straining pH or lowering the dosage of free SO2 age. Yet even if it affects perception more than chemical balance, the level matters. Peynaud also identifies at least some of the environmental factors that can influ- ence whether CO2 stays in wine or heads off do their dance through something called Henry's Law, formulated in 1803 by chem- ist William Henry, which holds that the sol- ubility of a given gas in a liquid at a given temperature is directly proportional to the pressure that same gas exerts on the liquid from outside. CO2 inside will inexorably depends mightily on temperature and other variables. At cool, jacketed-tank tempera- balance CO2 outside, but that balance point into the atmosphere. Temperature is crucial to solubility; the colder the temperature, the better the retention of carbon dioxide. Think of the nonstop chill necessary for making Moscato d'Asti, or the flatness of warm British beer. And so it is the amount of motion and agitation—anything from racking to swirling your glass—that pushes carbon dioxide on its way. Environmental factors and dissolved CO2 than oxygen, nitrogen or argon; at warmer barrel-room temperatures, the concentra- tion plummets rapidly. tures, CO2 is highly soluble—much more so needed for protecting wine from spoil- "If you're drinking the wine under five years from harvest, give it a little splash for air and it'll open up just fine." —Kurt Johnson, Beaux Freres winery Following Peynaud and other research- ers, the ballpark numbers are pretty well known. Wine emerges from fermentation with about two grams per liter of dissolved CO2 noticeable; at 1,000 mg/L, there is a slight perception of prickliness. The textbook recommendation is that age-worthy reds should be bottled with no more than 100- milligrams per liter, the presence of CO2 Patent # 7357069 , and it declines from there. At 500 is 200 mg/L; light, fruity reds could benefit from about 500 mg/L, and whites, depend- ing on stylistic intent, might range anywhere from 500 mg/L to 1,800 mg/L, from slightly punched up to noticeably spritzy. And oh, yes, at a tad under 4 grams per liter, which makes the wine officially spar- kling, the U.S. tax rate goes up. Paar and Hach both offer monitoring sys- tems in the $12,000-$13,000 range, with extra bells and whistles for a few dollars more. Both instruments sell primarily in other beverage sectors (beer, soda, etc.) but have a niche in large-scale wine process- ing as well. Hach's Orbisphere 3658 relies on measuring thermal conductivity, while Anton-Paar's CarboQC infers CO2 Counting carbon There are four basic methods for measur- ing dissolved CO2 content from repeated volumetric expansion. Both are highly accurate, but with daunting price tags for smaller producers. Next in line is a form of titration, the carbonic anhydrase test, which by every account is a colossal pain. Enology consul- tant Lisa Van de Water of Vinotec Napa describes the chemicals involved as "very nasty stuff," and she should know, hav- . At the high end, Anton- Inspired Design Our spirals made from Premium, American or French Oak deliver 100% new barrel flavor (8 months) in as little as six weeks. Now you can boast authentic oak flavor using neutral barrels or tanks – with rapid, controllable and predictable results. www.InfusionSpiral.com (800) 201-7125 West Coast–New York–Texas Len Napolitano (805) 712-4471 len@thebarrelmill.com Four toast levels Economical Sustainable Time-saving Wines & Vines MAY 2011 67