An Introduction To Oxidative Wine
- By Sabra Lewis
- 05 Apr 2021
- 5 MIN
- Level 101
Oxygen and time are the essential ingredients in the understanding of oxidative wines. So, what is an oxidative wine? Loosely put, it is a wine exposed to a controlled amount of oxygen at certain times during production.
The moment grapes are harvested from the vine, the clock starts ticking. Berries are exposed to oxygen through skin piercings and separation from the natural protections of the vine. Allowance of oxygen, or not, before and during maceration and pressing of the must is another critical time. There is a slight reprieve during alcoholic fermentation as oxygen does not thrive in the Co2 rich environment unless the winemaker introduces it. Perhaps the most significant period of oxygen exposure is during the maturation process of finishing and ageing wine. The variables here are many, giving the winemaker an enormous impact on the style of the finished wine we drink after bottling.
The Pendulum Of Oxygen
Oxygen exposure is not a bad thing in wine production. In fact, it is a vital necessity. It is the amount of exposure (and the timing thereof) that is critical. The difference being a wine of style and place or something closer to vinegar. Chemically speaking, too much oxygen exposure triggers a series of reactions that convert ethanol (alcohol) into acetaldehyde. Excessive levels of acetaldehyde in a wine not intended to be oxidative style is a fault. That is an oxidized wine. Not to be conflated with an oxidative wine, which is carefully controlled and chemically sound.
The opposite of oxidative winemaking is reductive winemaking, or winemaking with an absence of oxygen. In reductive winemaking, a winemaker would make decisions to mitigate the amount and impact of oxygen during the production stages mentioned above. The use of sulfur, inert gas, and stainless-steel tanks are routine practices for reductive winemaking.
Vessels Of Influence
The types of containers have a considerable impact on oxygen management. Producers wishing to make an oxidative wine might use oak barrels, concrete, or clay amphora, each with varying degrees of permeability and porosity. The goal is to introduce something called micro-oxygenation through these vessels or mechanically in stainless steel.
The closure of the bottled wine is notable to mention, playing the final role before consumption.
Oxidative winemaking, in part, stems from regional histories as winemakers adapted their finished product to their terroir and circumstances. Some of these decisions were accidental, as in the case of transporting wine in barrels on ships from Madeira to the New World. Others are more deliberate and borrow techniques inspired from other regions, such as introducing a modified Solera system from Sherry in Spain to cult producers in Champagne
Producers are often looking to achieve a certain textural complexity and flavour profile with oxidative wines. Oxygenation develops secondary and tertiary aromas and flavours: less overt fruitiness with the welcoming of savoury, umami, nutty, and dried fruit notes. Texturally, the wines tend to lie horizontally on the palate and have a marked integration of all of the measurable elements of wine, although this is wholly subjective.
Longevity or ageability is another motivator for winemakers to use oxidative techniques. Winemakers widely agree that micro-oxygenation during the winemaking process acts a bit like a vaccine bolstering the final wine from the adverse effects of oxygen later in the wine’s life.
Benchmarks Of Oxidative Wine Styles
Sherry, from the Andalucía region in Spain, is perhaps most widely known for oxidative winemaking. The styles of Sherry are entirely diverse, and not all fall into the typical oxidative classification. For example, the Fino and Manzanilla categories of Sherry are matured using Flor which is, in fact, a reductive environment that we call biological oxidation or biological ageing. Flor is a type of yeast that forms a protective layer on top of the wine shielding it from oxygen in a Sherry cask.
Sherry’s true oxidative style is an Oloroso, which matures slowly in cask in the absence of Flor as part of a Solera. A Solera is a complex system of groups of casks delineated by the average age of the wine, all in the same style for fractional blending. A portion of the oldest blends are drawn off for bottling and revived with the next oldest line, or scale, of casks called a Criadera. There can be many Criaderas in a Solera, depending on the Bodega’s intention. This act of fractional blending is in and of itself an oxidative process.
It is important to note that these wines are fortified to protect from excessive oxidation or spoilage. An essential characteristic of an Oloroso has to do with the effect of evaporation of water in each cask. This evaporation concentrates and intensifies the wine giving it the sharp structure and deep walnut flavours for which it is known.
The following are additional classic examples of oxidative styled wines, each with their unique properties:
- Vin Jaune - from the Jura in France (not fortified): long ageing in large untopped-off casks with a slow development of yeast called Voile
- Madeira - from the Portuguese island of Madeira close to the African Coast: fortified, heated, and oxidative ageing in cask
- Tawny Port – from Portugal: fortified and cask-aged for various periods
- Marsala – from Sicily: fortified and cask-aged for various periods, including, in some cases, the use of Soleras
- Vernaccia di Oristano - From Sardinia: aged in a Solera system
- Tokaji Szamorodni – From Hungary: a rare, dry Tokaji biologically aged under a veil of yeast