Stabilization refers to processes aimed at ensuring the wine remains clear, free of spoilage, and consistent in quality over time

Stabilization techniques are essential for ensuring the longevity and quality of wine after bottling:

• Tartrate Stabilsation (Cold Stabilisation)
  Prevents the formation of tartrate crystals in the bottle, which are harmless but can be unappealing to consumers.

• Microbiological Stabilisation
  Prevents spoilage caused by microorganisms such as bacteria and yeasts after the wine is bottled.

• Oxygen Stabilisation
  Prevents oxidation which can lead to undesirable changes in flavor, aroma, and color.

Winemakers often need to balance these methods carefully to maintain the desired characteristics of the wine while ensuring its stability during future storage and distribution.

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Tartrate Stabilisation

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Wine naturally contains tartaric acid, which can combine with potassium or calcium and form crystalline deposits (potassium bitartrate, "wine diamonds"). These crystals can form when wine is exposed to a long maturation period in a cold cellar, both before abd after bottling.

Cold Stabilisation

Cold Stabilisation involves chilling the wine to freezing temperatures -2°C/-4°C (28°F/25°F) for a period of time (typically 1-2 weeks). This forces the tartrates to precipitate out of the wine, which can then be filtered out before bottling.

Ion Exchange

Another method involves replacing potassium ions in the wine with sodium ions to reduce tartrate precipitation.

CMC (Carboxymethylcellulose):

A more modern technique involves adding CMC, a cellulose derivative, which inhibits tartrate crystallization and reduces the need for cold stabilization.

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Microbiological Stabilisation

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Wine can be susceptible to contamination by spoilage organisms, including lactic acid bacteria (responsible for malolactic fermentation) and acetic acid bacteria (which can cause vinegar-like spoilage), as well as various wild yeasts.

Sulfur Dioxide (SO₂)

SO₂ is the most common method for controlling microbial activity in wine. Sulfur dioxide acts as an antimicrobial and antioxidant agent. Winemakers add SO₂ during various stages of winemaking, including at bottling, to maintain microbiological stability.

Filtration

Sterile filtration, especially membrane filtration (typically with pore sizes of 0.45 microns or smaller), can physically remove microbes from the wine before bottling.

Flash Pasteurization

Some wineries use heat treatment, rapidly heating the wine to a specific temperature and then cooling it, to kill any microorganisms present.

Dimethyl Dicarbonate (DMDC)

DMCS is a chemical sterilant used to kill yeast and other microorganisms in wine before bottling, without affecting the taste.

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Oxygen Stabilisation

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Oxygen exposure can lead to the oxidation of wine, which might result in browning, loss of fruitiness, and the development of off-flavors such as sherry-like notes. Even minimal oxygen exposure during aging or bottling can affect the wine’s quality.

Sulfur Dioxide (SO₂)

Beyond its role in microbial stability, SO₂ also acts as an antioxidant, protecting the wine from the effects of oxygen. It binds with oxygen and neutralizes its ability to cause oxidative reactions.

Inert Gas

The use of inert gases (like nitrogen, argon, or carbon dioxide) can displace oxygen during bottling or tank storage, reducing the wine’s exposure to oxygen.

Vacuum Bottling

Some bottling processes involve creating a vacuum in the bottle to remove oxygen before sealing the wine.

Ascorbic Acid

Sometimes used in conjunction with SO₂, ascorbic acid (vitamin C) can help prevent oxidation by acting as an additional antioxidant.

Oxygen-Scavenging Closures

Specialized wine closures, such as certain synthetic corks and screw caps with oxygen-absorbing layers, are designed to limit or control oxygen ingress into the bottle over time.

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Chapter Summary

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Subject	Outcome
Tartrate Stabilisation	Cold Stabilization prevents the formation of tartrate crystals in the bottle. It involves chilling the wine to freezing temperaturesfor 1-2 weeks.
Microbiological Stabilisation	Prevent spoilage caused by microorganisms such as bacteria and yeasts. SO₂ is the most common method for controlling microbial activity in wine.
Oxygen Stabilisation	Prevent oxidation, which can lead to undesirable changes in the wine. Beyond its role in microbial stability, SO₂ also acts as an antioxidant.