Practical Winery
65 Mitchell Blvd, San Rafael, CA 94903
phone: 415-453-9700 ext 102
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November/December 2007
Tannat [the pre- dominant variety of Madiran, France were microOx started], dominant variety of Madiran, France were microOx started], Petit Verdot, Malbec, Barbera, and Ruby Cabernet) and occasionally Chardonnay. For the reds, color and fruit development, palate fullness, diminished reductiveness, and improvements in the vegetal characteristics are the reasons for using microOx.
MicroOx is done in tanks with oak inserts, regardless of whether a wine will go to barrels or not.
"At times, we will microOx Chardonnay to help control the reduction potential when ageing sur lie in stainless steel tanks," explains Ziemann. "Our goal is to age on yeast lees, and using small amounts of microOx with lees stirring can be beneficial in keeping the wine in the positive (sweet aroma) direction. Not all white wines react in this way, you need to be very careful."
Both the Oenodev and Parsec equipment are used and the advantages of both systems are still being evaluated. MicroOx is done right after fermentation and continued through MLF. After MLF, with the rate of oxygen reduced, microOx is continued for only two to four weeks.
Along with regular tasting, the dissolved oxygen is monitored daily, especially with the higher rates used early in the program, to determine the amount of O2 needed. Regular monitoring of free SO2, VA, pH, TA, malic acid, and temperature is also done.
Some aldehyde formation is desired, so SO2 is added only after MLF, and is adjusted to 20 ppm free. In the early stages of microOx, temperatures are kept at 18°C (64°F) and then lowered to 14°C (58°F) after MLF. Ziemann is very aware of the increase in dissolved oxygen as the temperature drops.
Deciding whether a wine should receive microOx is often difficult, especially when the parameters are marginal. Ziemann uses the following to make determinations:
Sugar - close to dry, no higher than 2 to 3 g/L,
pH - 3.7 or lower,
Color - visual,
Tannin - winemaker taste,
Reduction character - winemaker taste.
Ziemann emphasizes that microOx, like all winemaking technology, needs to be incorporated into the total winemaking program. He and his team started with small experiments in 1998, and then put it into limited production in 1999. Experience gained each year has been invaluable.
He notes with the improvements that, "the equipment is much easier to use
being computer-based/webbased. One can monitor more lots in much less time." He sees the use of microOx as a continuum and will be examining other varieties to see if they might benefit from microOx.
While not normally noted, wine ageing and enhancement of the wine/food paring are also considerations for the use of microOx. Ziemann's experience, while still rather limited, is that microOx doesn't detract from either age worthiness or wine/food paring.
Five-tank remote controller for the Parsec micro-oxygenation system.
Five-tank remote controller for the Parsec micro-oxygenation system.
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