Issue link: http://winesandvines.uberflip.com/i/101495
WINEMAKING After three or four days of imperceptible activity, winemaker Eric Baugher irrigates the cap to extract color and tannin. In addition, pump overs help mix yeast from the bottom of the tank, redistributing it throughout the fermenting juice. Exploring possibilities A spontaneous fermentation is the medley of unpredictable microbes that survive the harsh conditions of anaerobic must. According to Bisson, Kloeckera apiculata or Hanseniaspora uvarum is the most common yeast, fresh from the vineyard at 65% to 85% of total isolates, with Pichia and Candida comprising closer to 10%. Saccharomyces can number 1 in 10 million native yeast. Approximately 100 native yeast cells populate a milliliter of freshly fermenting Ridge Cabernet Sauvignon, Zinfandel or Chardonnay. With most winemakers inoculating 10,000 times more commercial yeast per milliliter, conventional fermentations start much more quickly than native fermentations. Kloeckera apiculata begins to multiply as soon as the grape skins are broken. It can deplete the must of vital nutrients and Juice collected from tanks at first pump over and squeezed from grapes found from various vineyard parcels are analyzed for Brix, malate, pH and TA. produce 25 times more acetic acid than Saccharomyces. Because the initial population of Saccharomyces is so small, Kloeckera drives the early stages of fermentation. Fortunately for winemakers Draper and Baugher, Kloeckera favors cooler temperatures and lower concentrations of ethanol. Kloeckera limits growth when temperature climbs to 20��-25��C and stops fermenting entirely when ethanol concentration reaches 2% to 3%. Saccharomyces cerevisiae and related species have an optimal temperature range of 25��-35�� and continue to ferment until the winemaker determines fermentation is complete. ���We are constantly asking: What���s the temperature of the winery?��� Baugher says. ���If the must is too cold, we warm it up.��� The cellar team starts pump overs the morning after crush. Following three or four days of aerated pump overs, the must begins to ferment vigorously. While extractions are slow at first, rising temperature accelerates fermentation. Cabernet Sauvignon peaks at 33��, Zinfandel at 29��. ���We control the temperature of each tank manually,��� Baugher says. ���There are no punch downs, and we aerate twice a day.��� As the temperature and concentration of ethanol rise, Saccharomyces overtakes Kloeckera, Candida and Pichia. These native yeast die after dominating the early and middle stages of fermentation, leaving Saccharomyces to finish the process. Changing the temperature profile and pace of production preserves flavor and aroma. ���A slower and cooler fermentation means better retention: less volatilization or loss of varietal character,��� Bisson says. Although the rate of fermentation depends on many factors, native yeast can take twice as long to complete fermentation as commercial yeast. Winemaker Eric Baugher samples press fractions. He declassifies the early and late fractions. At 0.3 to 1 atmosphere, the middle fraction is the essence of the grape. ���We guide the process along, close to dryness,��� Baugher says. ���As the tannins come on, we press.��� Adding character Like native yeast, native lactic acid bacteria can take longer to ferment than commercial inoculants. Only four genera���Lactobacillus, Leuconostoc, Pediococcus and Oenococcus���can survive low pH, low nutrients and high concentrations of ethanol. Temperature matters, too. Ambient temperature can fall to 10��. Malolactic bacteria populations grow when the temperature of the fermentation ranges from 15�� to 25��. The ideal temperature for Oenococcus oeni, a commonly used inoculant, is 20��-22��. The cellar team stores the fermenting wine in a square 1,000-gallon stainless steel tank with a partially closed threefoot lid and reinforced ribs containing heating coils that hold the temperature at 17��-20��. During fermentation, native lactic acid bacteria���like native yeast���can enhance the flavor. The slower rate of a spontaneous fermentation can yield higher concentrations of diacetyl���a compound that can add a buttery flavor to wine. ���Once the Cabernet has undergone half the malolactic fermentation,��� Baugher says, ���we know there is a good culture present for us to safely rack the wine into barrels. We store it in barrels on its gross lees for three or four months so the malolactic fermentation can finish uniformly. The Zinfandels, however, complete malolactic before we send them to barrel.��� To reduce the risk of oxidizing or spoiling the wine, the winery team adds small amounts of SO2 before crush, immediately Win es & Vin es JA N UA RY 20 13 65