Practical Winery
65 Mitchell Blvd, San Rafael, CA 94903
phone: 415-453-9700 ext 102
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November/December 2007
and veggie characteristics, and to add an oak baseline with continued wine development prior to going into barrels. The results have been softer tannins in the finished wines, significantly boosting sales in the market place.
Meier uses both the mg/L and ml/L measurements (1 ml = 1.4 mg). This is because the winery utilizes both the Parsec and Oenodev systems. They started incorporating microOx in 2002, experimenting with several brands. Parsec and Oenodev were chosen for the service available, especially important in the early trials to help gain experience quickly; the safety features of the units, such as a back pressure monitor; single units that can control multiple tanks; and the ease of adjustments.
Meier notes that microOx is "a tool in the winemaker's toolbox." Like all tools, it is designed for specific uses. Meier tried microOx on Sauvignon Blanc with little success. He still feels that barrel-aged wines offer a bit more complexity and finesse than those aged in stainless steel tanks with microOx and oak chips or inserts. With the total cost of using microOx about one-third that of using barrels, for some wines, especially those selling at low price-points, microOx becomes an invaluable tool.
Michael Havens, winegrower at Havens Wine Cellars (Napa, CA), started experimenting with the introduction of oxygen into wine in 1997 using homemade equipment. In 1998, after visiting Patrick Ducournau in Madiran in southwestern France, he learned more about the technique and realized that commercial equipment was available. He is utilizing an Oenodev unit to microOx select wines.
"MicroOx is not simply a tool to push a wine toward softness and marketability," states Havens, "that is always a choice the winemaker makes. He/she can just as well use microOx to make a hard-boned, long-ageing wine if so desired. Free/total SO2
ratios are much higher in most microOx wines, a good technical advantage in itself."
It is the control precision that microOx provides that Havens appreciates, allowing him to make these decisions with confidence. But the use of microOx requires more direction from the winemaker, Havens emphasizes.
Tannin structure is a major consideration in the use of microOx. Havens defines the cyclical textural path of tannin as: 1) green, 2) hard, 3) firm, 4) soft, 5) round, 6) melted, and 7) green (when overdone). He feels it is usually best to bottle when wines are in the firm/soft stage.
Havens produces Merlot, Cabernet Sauvignon, Cabernet Franc, and Syrah. As these all have significant anthocyanin structure, he is comfortable using microOx for any of these wines, regardless of their tier in the winery production hierarchy. If he were making Pinot Noir or Grenache, with their typically lower levels of anthocyanins and tannins, he would be using microOx much less.
Havens' approach for an age-worthy wine is to micro-ox at 60 to 80 ml/L/month starting at primary dryness. The addition is then stepped down at about the same point when MLF finishes. SO2 is added and the wine is settled. After two to three weeks, microOx is resumed, beginning at a rate of 40 ml/L/month, and then decreased to 5 mL/L/month for about one month. The wine is then ready for barrel ageing, where occasional additions of "punctual," or brief, oxygen continues to develop the wine.
Dave Guffy, director of winemaking for the Hess Collection Winery (Napa, CA), applies microOx to cure the occasional herbal or vegetative character, or a reductive quality, from some vineyard lots of grapes for Hess's California Series wines. "Checking into the hospital" is his analogy for correcting these problem wine
lots. Guffy does not use microOx to reduce tannins or minimize the use of oak barrels, and the wines must have enough structure to tolerate the increase in oxygen. Done after MLF and sulfur additions, the treatment might last from one to six months, and the rate is typically at 1 to 5 mL/L/ month, adjusted by monitoring the taste of the wine. In the 2006 harvest, only two lots with H2S required microOx.
The StaVin OxBox is used at Hess, shifting the several lines from tank to tank as needed. Guffy likes the simplicity of OxBox, requiring one to merely calculate the desired amount of oxygen, and then adjust the flow rate and set the timer. He and his crew taste every other week, and watch the dissolved oxygen rates in the wines. (The OxBox's back pressure meters are provided more to note when the spargetips are clogged rather than adjusting for tank pressure.)
While most wineries are using microOx in stainless steel tanks, Jeff Hinchliffe, winemaker at Hanna Cellars (Healdsburg and Santa Rosa, CA), pumps O2 to Cabernet and Merlot placed in 1,100 to 3,300-gallon wooden uprights. Selectively using microOx on wine with good color and high tannins, this use of MOx in wooden tanks typically represents only 15% of the total blend. Oak inserts are added to get a jump on the oak integration prior to going to French, European, and American oak barrels.
Used after primary fermentation, Hinchliffe's rates are normally 3 mg/L/ month until MLF, and then reduced to 0.5 to 2.0 mg/L. If a wine is on primary lees, a rate of 5 or 6 mg/L might be used. With the reduced rates, the wines can stay in tanks until midsummer. Whenever using microOx, Hinchliffe and his staff monitor by tasting weekly, smelling for aldehydes, and checking the DO level. In a recent high press lot of Merlot the aldehyde rate rose, and the microOx rate was reduced.
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