How to Prevent Wine Oxidation 

Oxidation is one of the most obtrusive wine faults. It can lead to discoloration, lackluster flavor and even turn the wine into vinegar if enough time passes. Preventing oxidation is a critical step necessary to produce quality, desirable wines.

For many wines, allowing some oxidation to occur after opening a bottle and pouring a glass can help bring out all of its aromas and flavors for a richer wine-tasting experience. This is why you may see wine drinkers swirling the wine in their glasses before tasting it.

While many wines offer a fuller experience when exposed to oxygen before consumption, too much oxidation can ruin a good wine.

Wine Oxidation Explained

Wine oxidation occurs when the wine is exposed to too much oxygen. Fully oxidized wines are spoiled and no longer considered drinkable.

The oxidation process occurs when the wine is exposed to air, triggering a series of chemical reactions that convert alcohol into acetaldehyde. This process is one of the most common wine faults since oxygen and a catalyst — like the pigments found in red wine — are the only requirements for it to occur.

Oxidation can happen at any stage in the winemaking process, even after its bottled. Any time the grapes or juice is exposed to air, there is oxidation potential. Many factors and stages in the winemaking process can promote oxidation, including:

• Ruptured grapes: Pierced or damaged grapes allow oxygen to enter. This process can fuel the growth of enzymes such as laccase, which, when combined with oxygen in the winemaking process, will produce negative qualities in the final product.
• Faulty corks: Some corks intentionally let in small amounts of oxygen to draw out favorable characteristics in the wine. A faulty cork may allow too much oxygen into the bottle, contaminating the wine and resulting in an overly oxidized drink.
• Containers with high oxygen permeability: Like with corks, many aging containers, such as oak barrels or concrete vessels, allow some airflow for a more complex result. Too much oxygen negatively impacts the wine if these containers are not closely monitored throughout the long aging process.
• Pressing and crushing process: These stages in the winemaking process can open up opportunities for the grapes and extracted juice to come in contact with oxygen. Working efficiently and with the proper equipment can help minimize the wine's exposure to air.
• Bottling: Exposure to oxygen is inevitable any time the wine is moved between containers. Winemakers transport the product from various vessels throughout the winemaking process. One of the most notable instances is the final bottling stage when makers move the wine from its aging container into marketable bottles. You can keep the exposure to a minimum by using proper techniques and the right tools.

Oxidation can not be reversed, and with enough oxidation, the wine can transform into vinegar.

Oxidative Versus Oxidized Wine

In the wine community, there is a significant difference between oxidized wine and oxidative wines. While oxidized wines are faulty and undrinkable, oxidative wines offer a fulfilling and unique wine experience. Oxidative wines have been intentionally exposed to oxygen during the winemaking process to obtain a special character or quality.

When winemakers add small, controlled amounts of oxygen to a batch of wine, it can add many favorable qualities and become an enjoyable and desirable product. It is only when an uncontrolled amount of oxygen contaminates wine that it creates unfavorable characteristics and fully oxidizes.

Making oxidative wine is a delicate process. Similar to when you dry-age meats, winemakers sacrifice an aspect of the original product to gain a more complex and satisfying result. Winemakers achieve this by stressing the original stock through controlled oxidation to enhance its most favorable qualities in response.

Sherry and Madeira are two common wines made with intentional oxidation. These products are prized for their complexity and rich qualities. Many regions produce oxidative wines, but it is especially prolific in the Jura region in France. Here, many white wines are exposed to oxygen in the barrels in which they are aged.

There are several distinct ways to cultivate oxidative wines, including:

• Oak barrels: These barrels allow small amounts of air to pass in and out, controlling the rate at which the wine is oxidized.
• Cement tanks: Cement wine cases are naturally porous and let small streams of air move through the container.
• Open-tank fermentation: Open wine fermentation can work because the carbon dioxide produced by yeast in the fermentation process creates a blanket for the wine. Winemakers need to cover the wine to protect it at a certain point.

How to Tell if Wine Is Oxidized

Noticing when a wine is oxidized is a valuable skill, whether you are a winemaker or a connoisseur. When dealing with an overly oxidized wine, it's essential to recognize the warning signs and avoid accidentally serving or selling the product. Oxidation is a common fault, so it's important to be aware and look for the telltale signs of unintentional oxidation.

Here are a few giveaways that your wine has been tainted by too much oxidation:

• No aroma: Instead of the full, fruity aroma you expect from a typical wine, oxidized wine is odorless and flat.
• Slightly brown: Both red and white wines become somewhat discolored when oxidized. White wines appear darker than expected, while red wines lose their purple undertones and begin browning.
• Lackluster palate: Oxidation rids the wine of its rich, complex qualities and leaves a flattened and dull flavor.
• Vinegar taste: Depending on how much oxidation has occurred, you may detect notes of vinegar in the wine. If left unchecked, your wine could turn into vinegar.

Avoid serving or drinking oxidized wine, as its good qualities will have deteriorated. Instead, look for alternative uses. You can still cook with oxidized wine and use it to marinate meats or add body to soup. You can also add oxidized red wine to a bath to take advantage of its skin-softening antioxidants. You can use soured white wines to remove red wine stains.

How Air Compressors Can Help Combat Wine Oxidation

Air compressors serve many functions in the winemaking industry and offer a more efficient and safer solution in several steps throughout the winemaking process. Access to controlled compressed air can reduce the risk of oxidation and help winemakers complete the task more quickly and effectively.

Here are some of the ways air compressors can improve winemaking and limit oxidation.

Controlled Aeration

Aeration is the process of introducing controlled amounts of oxygen to the wine to round out and soften its qualities. Using a quality air compressor is the best way to achieve this and prevent over-oxidation. Using pressurized air with an air compressor gives winemakers an easily controllable method to aerate the wine, allowing it to breathe before the bottling process without risking oxidation to a fault.

Bottling Techniques

When bottling wine, it's vital to monitor dissolved oxygen (DO) levels, as this step can affect the oxidation of the wine. Winemakers employ several key techniques to keep DO at an appropriate level to produce quality wine. This is particularly important for white wines, which do not react as well to slight oxidation increases as red wines.

Air compressors are commonly used throughout the bottling process. Winemakers use large volumes of compressed air to push the wine from its holding tank into barrels or bottles to minimize oxidation. Pressurized air also helps keep the pneumatic lines clear and the wine clean throughout the procedure.

Crushing and Pressing Grapes

Crushing and pressing grapes are crucial steps with a high potential for oxidation since the grapes are fully exposed to air. You can use air compressors in both processes to more effectively combat the risk of oxidation.

Many winemakers use air compressors with special equipment, such as bladder presses, to extract the liquid left after pressing or crushing grapes. The compressor produces pressurized air and inflates the vat, crushing the grapes. This process pushes the juices out of the vent holes.

Professional Labeling

The labeling process is an essential aspect of winemaking. A refined and eye-catching label with seamless application indicates a higher quality wine. Labels are a major component of how most people choose their wines at the store.

Winemakers can use air compressors for a clean, flawless application. The right air compressor gives labels a more professional look, making them more appealing to potential customers.

The Sparging Process

The sparging process helps remove dissolved oxygen from wine, preventing oxidation. During the procedure, nitrogen is applied in very fine bubbles to remove the dissolved oxygen, improving the wine's flavor and increasing its shelf life. It also helps eliminate volatile contaminants and makes the winemaking process more efficient.

Sparging requires compressed air, and the most effective method to accomplish this is with an air compressor.

Other Ways to Prevent Wine Oxidation

Aside from using air compressors to expedite processes and reduce the risk of oxidation, winemakers employ additional methods to prevent harmful oxidation throughout the winemaking process.

1. Practice Good Canopy Management

When you take extra care to protect your grapes with strong canopy management, you increase your likelihood of producing high-quality wines. Laccase-producing fungi thrive in the growing season. Laccase is an enzyme released into the grape that oxidizes and harms the wine's desirable aromas and qualities when it combines with oxygen.

The best way to combat laccase is through prevention. Keep an open canopy that lets air flow freely to reduce moisture and fungal growth on the grapes. If you notice fungi, minimize oxygen exposure to prevent further laccase growth.

2. Use an Inert Gas Cover

Transferring wine from tank to barrel to bottle is a crucial part of the winemaking process. Moving the wine between containers requires the flow of wine into empty, air-filled vessels. This means the wine will inevitably come into contact with oxygen.

Using an inert gas cover effectively limits the wine's exposure to oxygen to an absolute minimum. Inert gas protects the wine as it moves from one container to another when air is displaced in the racking and receiving container. Nitrogen and carbon dioxide are two commonly used inert gases in the current wine industry. Sometimes winemakers use a mixture of these gases.

3. Add Sulfur Dioxide

Sulfur dioxide (SO₂) is a common additive in wine. Free SO₂ helps reduce wine oxidation and prevent spoilage. Sulfite prevents oxidation by inactivating enzymes that produce harmful effects to the wine when exposed to oxygen.

Adding larger, less frequent doses of SO₂ yields greater concentrations of free SO₂, making it a much more effective strategy for achieving the desired chemical makeup in wine.

4. Choose the Right Corks

If you're aging your wine in a bottle, your choice of cork significantly impacts how the wine ages and how much oxygen it will be exposed to over time. Natural corks made from evergreen oak trees are very porous and allow 0.005 to 5 milligrams per liter per year into the bottle. Over years of aging, this can lead to oxidation if you did not initially account for it.

Several other cork choices are less porous and vary in the amount of oxygen they allow into the bottle, including synthetic corks and screw caps.

5. Monitor Wine Barrels Closely

While aging wine in barrels is a common technique to slowly introduce oxygen to the wine and draw out its finer qualities, minimizing this exposure helps preserve its integrity. Wine can soak up within the porous barrels' staves, increasing headspace inside and leaving more room for oxygen. Ethanol and water in the wine may also evaporate at the barrel's surface of the barrel, creating even more open headspace.

Closely monitor your barrels and top them off frequently to prevent too much oxygen exposure in the added headspace.

Contact Fluid-Aire Dynamics for Quality Air Compressors

Fluid-Aire Dynamics provides high-quality air compressors that let you control or minimize oxidation while optimizing your winemaking process for speed, quality and efficiency. With more than 40 years of industry experience serving companies of all sizes nationwide with locations in Illinois, Wisconsin, Minnesota, Texas, Michigan and Pennsylvania, Fluid-Aire Dynamics offers first-rate service and products you can rely on to get the job done right the first time and create the perfect bottle of wine for your consumers.

Choose Fluid-Aire Dynamics for superior system design, 24/7 emergency services and the best return on investment in the marketplace. Fill out an online contact form to learn more about how the equipment and expertise at Fluid-Aire Dynamics can benefit your winemaking facility. One of our specialists will be happy to get back to you soon.