Vinquiry, Inc., a Windsor, California-based supplier of enological services and winery supplies, is increasingly serving up popular educational seminars in addition to their usual Erlenmeyer flasks and Fermaid-K. On December 5, 2006, at the Doubletree Hotel in Rohnert Park, California, they put on yet another sold-out seminar, "The Role of Oxygen in Winemaking." Oxygen is a wide-reaching, implication-rich topic that is often at the top of winemakers' minds as we start the new year by assessing our wines' reductive capacity, aging needs and future racking regimens. The scope of the seminar was therefore, by default, ambitious. Speakers from the U.S. and France covered some general territory, delved into the details of micro-oxygenation, detailed French research results about the role of oxygen in fermentation and discussed some hands-on tips and observations from their own cellars.

Careful note-takers (especially those already fluent in the parlance of micro-oxygenation, cliqueage and microbullage) were able to garner some useful information. However, many in the audience seemed to be new to the industry and perhaps left the seminar with more questions than answers. Since the topic of oxygen in wine is vast in its scope and audience, perhaps future global-theme gatherings could be carved into mini-seminars geared towards specific groups and levels of interest or could be stretched over a full two days, allowing busy winemakers to choose those sessions that add clear value to their organizations.

O₂ in Wine: The View From 10,000 Feet

The overriding theme of the event can be encapsulated by Dr. Grady Wann's introduction: "Oxygen in Winemaking: Both Friend and Foe." In what was a concise summary of the most important ways in which oxygen affects winemaking (and the decisions winemakers must make), he took participants through a general but thorough look at oxygen's interactions with fermenting must and barreled and bottled wine. I especially appreciated his last slide, on which were outlined the following three nuggets of winemaking wisdom:

(1)Oxygen is everywhere-we can't live without it.

(2) Oxygen's impact should be considered in all of our winemaking decisions.

(3) Oxidation and reduction systems are very complex in juice and wines, so be careful when
extrapolating.

The ICV explores O₂ in the Mediterranean

All three sentiments, especially the last, were echoed by Institut Coopérative du Vin (ICV) consulting winemaker/ researcher Adrien Debaud. The ICV is a major supplier of consulting, R&D support, and technological assistance to grape growers and winemakers in the Mediterranean winegrowing regions of Spain, France and Italy. The caution that what works for one winemaker may not work for another was especially true with regards to Debaud's detailed dual presentations, which covered the quality impacts of introduced oxygen during alcoholic fermentation and an explanation of micro-oxygention's effects on young wines as they age. Since most of the research presented was based in the Mediterranean, Debaud was quick to point out that what works for Grenache in Southern Spain may not work for Cabernet Sauvignon in the Alexander Valley.

Not always easy to follow, Debaud's presentation mainly described and prescribed specific oxygen-introduction regimes enacted on experimental grape wines during fermentation and after fermentation was complete. Though it might be difficult for California winemakers to formulate specific micro-ox regimens for their own wines based on Debaud's examples (especially challenging because of differences in raw materials and available equipment in the U.S.), his extensive experience (as well as the ICV's impeccable follow-up and long-term tracking of wines) allowed him to share some general research results about oxygen and wine:

• Lees act as oxygen scavengers and can provide some protection against oxidation, but only until they are used up.

• A drop of 5°C increases oxygen solubility by 10 percent in wine-be very careful to avoid over-oxidation in cold wines.

• Rate of alcoholic fermentation (AF) is slower without introduced oxygen and higher with it.

• High volatile acidity production during AF is associated with low levels of oxygen (due to yeast stress).

• Introducing oxygen during fermentation can result in more fruit-forward wines, even after five years in the bottle.

• Direct pumping over of a red ferment doesn't add any dissolved oxygen because the cap is saturated with CO₂.

• If you want to measure the amount of O₂ you introduce to a fermentation, 1 second at 3 bar pressure per Hl wine = 1 mg/L dissolved O₂.

• Be conservative with levels of oxygen when micro-oxygenating high pH, high-yield, low-anthocyanin, low-tannin wines.

• Micro-oxygenation isn't the answer for every wine-it is simply a tool that can be used to increase the overall quality of wines that need a little extra oxygen "push."

The ICV has done quite a great deal of research as well as experiments in micro-oxygenation of juices, musts and wines; they are definitely pioneers in popularizing this kind of technology. For further information, visit the ICV's website at www.icv.fr.

O₂ in Aging, Bottling and Maceration

After lunch, some California-based winemakers shared their hands-on experience with oxygen during various times in the winemaking year. John Giannini of Fresno State University discussed what he called "Practical Considerations for Wine Aging;" and Scot Covington of Trione Vineyards & Winery explained how he has rigged up a special air-introducing pump-over device in his own cellar to really introduce air rather than just move wine around in a CO₂-rich atmosphere. Michael Havens of Havens Wine Cellars discussed some of his micro-oxygenation "recipes" (application rates and timeline) for wines with different style goals and aging parameters, and then Ronald Du Preeze of Jordan Vineyard & Winery talked about dissolved oxygen with regards to bottling-how to control it and how to avoid it. Though misnamed a "panel discussion," these presentations provided some useful takeaways for the attendees:

An O₂ Factoid Crib Sheet

In John Giannini's talk on "Practical Considerations for Wine Aging" he reviewed the following points:

• Oxygen reacts with phenols to
produce hydrogen peroxide, which reacts with ethanol to produce acetaldehyde.

• Sulfur dioxide doesn't provide anti-oxidant protection by interacting directly with oxygen. It acts on the products of oxidation, i.e., aldehydes.

• Typical oxygen pickup rates for cellar movements:

• Tank-to-tank wine movement:
0.1-0.2 mg/L

• Aerative splashing: 7.0 mg/L
(still wine)

• Normal processing and aging in barrels: 26 mg/L

• Introducing air into a sulfide-defected wine isn't always the answer. Sulfides can turn to mercaptans, which can turn into disulfides (almost impossible to get rid of).

• DO measurement depends on where in the tank it's taken-near the surface of wine will present higher DO than in middle of tank.

• To minimize oxygen ingress during barrel aging, maintain cellar temperatures at 55-65°F and humidity at 60-70 percent.

• Barrels aren't impermeable containers.

• If relative humidity is less than 60 percent, water evaporates from barrels and percent of ethanol increases; if relative humidity is greater than 60 percent, ethanol evaporates. In both cases, headspace and a vacuum are formed (if the bung is in tight).

Michael Havens reviewed the following points in his talk, "Why Use Micro-Oxygenation During Aging?"

• You can build structure and develop texture with less SO₂ in your winemaking.

• Micro-ox takes a wine on a cyclical textural path of: (1) green, (2) hard, (3) firm, (4) soft, (5) round, (6) melted and (7) green. It's best to bottle when wines are in the firm/soft stage.

• Micro-ox recipe for an age-worthy wine you're taking to barrel in January: micro-ox at 60 ml/L/month starting at primary dryness, then drop gradually down to 0 in the week before ML fermentation stops. Add SO₂ and settle the wine for a few days. Next, crank the micro-ox back up gradually to 40 ml/L/month over two weeks, and then gradually decline the oxygen to about 5 ml/L/month before taking to barrel in January.

• Micro-ox is a great tool for making sure you're landing a wine at a certain stylistic point right before bottling-a stylistic point that's appropriate for the wine as well as your house style.

Ronald Du Preeze, who spoke about "Dissolved Oxygen and Bottling," reviewed the following:

• Try to bottle with DO less than 1.0 mg/L.

• Jordan procedure developed for bottling under 1.0 mg/L

• DO check on next day bottling tank.

• Gas filter bowl and transfer line with Argon.

• Before startup, cycle wine back from sterile membrane filters back to filter (and from tank to filter) for 10 minutes (about 100-150 gallons) to flush oxygenated wine from the system.

• At the end of bottling, stop filler and remove the last 40 gallons (cycle back to filter).

• Use "on demand" gas system (Argon) on all bottling tanks; push wine back to tank with Argon at the end of the day.

Despite the seemingly ambitious goals of the seminar, a great deal of vital information was conveyed. wbm

For information on upcoming seminars, contact Vinquiry, Inc. at 7795 Bell Rd., Windsor, CA 95492 (707) 838-6312 www.vinquiry.com.

For further discussion of the role of oxygen in winemaking, see Lance Cutler's "Achieving Balance in Reductive Winemaking" that was featured in the October 2006 issue of Wine Business Monthly.