Wine is a beloved beverage enjoyed by millions worldwide, but what goes into making it? While the primary ingredients in wine are grapes and yeast, the production process can involve various chemicals—some natural and some added for specific purposes. Let’s explore what chemicals are used in wine, their functions, and how they might affect your drinking experience.

1. Sulfur Dioxide (SO2) – The Preservative

One of the most common chemicals in wine is sulfur dioxide, often referred to simply as “sulfites.” Sulfites are used primarily as preservatives to prevent oxidation and microbial spoilage. They help maintain the wine’s freshness, stabilize its color, and prevent it from turning into vinegar. Sulfur dioxide also acts as an antioxidant, protecting the wine from the effects of exposure to air once it’s bottled.

How it affects you: Some people are sensitive to sulfites, experiencing headaches or allergic reactions. This is why wines often carry a warning on the label if they contain more than 10 parts per million (ppm) of sulfites.

2. Tannins – Natural Antioxidants

Tannins are naturally occurring compounds found in grape skins, seeds, and stems. They are also present in oak barrels used in aging wine. Tannins contribute to the texture and mouthfeel of wine, giving it a dry sensation. They play a significant role in the wine’s aging potential by acting as antioxidants, helping preserve the wine over time.

How it affects you: Tannins are responsible for the bitterness and astringency in red wines, which can vary based on the grape variety and winemaking techniques. For some people, tannins may also cause mild mouth irritation, especially when consuming highly tannic wines like young reds.

3. Acids – Balancing the Taste

Acidity is a crucial component of wine that affects its taste, structure, and preservation. Wines naturally contain several acids, including tartaric, malic, and citric acids. These acids are responsible for the tart, crisp flavor found in many wines, particularly white wines. They also help balance the sweetness of the wine, enhancing its overall profile.

How it affects you: The acidity in wine can influence its mouthfeel and flavor. High-acid wines like Sauvignon Blanc or Riesling are often refreshing and lively, while low-acid wines like Merlot or Chardonnay can feel rounder and softer on the palate.

4. Fining Agents – Clarifying the Wine

Fining agents are chemicals used to clarify and stabilize wine. These agents help remove unwanted particles or proteins that may cause the wine to be cloudy. Common fining agents include egg whites, gelatin, bentonite clay, and isinglass (fish bladder extract). They work by binding to these particles, making them easier to remove through filtration.

How it affects you: Fining agents are generally removed before the wine is bottled, so they don’t affect the taste directly. However, some vegans or vegetarians may prefer wines that are labeled as “unfined” or “vegan-friendly” since certain fining agents are animal-derived.

5. Sugar – Adjusting the Sweetness

While grapes contain natural sugars, some winemakers may add extra sugar during fermentation to increase the alcohol content (a process called “chaptalization”) or to adjust the sweetness of the wine. This is more common in colder wine regions where the grapes may not ripen fully.

How it affects you: The sugar level in wine can drastically change its flavor profile, turning dry wines into sweeter varieties. If you’re sensitive to sugar or watching your intake, the sweetness level of a wine can influence how you enjoy it.

6. Acidifiers – Boosting Acidity

In some cases, winemakers may add acidifiers like tartaric acid to adjust the acidity of the wine. This is typically done to balance the taste of the wine or to correct issues in the winemaking process, such as when grapes are harvested too late in the season and the acidity is too low.

How it affects you: Acidifiers, like naturally occurring acids, can contribute to the wine’s overall sharpness or tartness. Wines with higher acidity often pair better with food, while wines with low acidity may seem flat or dull in comparison.

7. Yeast – The Fermentation Agent

Yeast is a key player in the fermentation process, converting the sugars in grapes into alcohol and carbon dioxide. While wild yeast is sometimes used, many winemakers rely on cultured yeast strains to control the fermentation process and ensure consistency.

How it affects you: Yeast can influence the flavors and aromas of the wine. For example, certain yeast strains can contribute fruity, floral, or even spicy notes to the finished wine. The fermentation process also impacts the texture and mouthfeel, with some wines undergoing malolactic fermentation (converting malic acid to lactic acid) for a creamier, softer taste.

8. Oak – Flavor and Aroma Additive

Many wines are aged in oak barrels, which can impart a variety of flavors and aromas. The oak wood itself releases compounds like tannins, lignin, and phenolics into the wine. The level of toasting on the barrel also affects the flavor, with lighter toasts giving subtle flavors and heavier toasts contributing bold, smoky or vanilla-like notes.

How it affects you: Oak aging can provide wines with complex flavors such as vanilla, spice, caramel, and smoke. These characteristics are particularly evident in wines like Chardonnay and Cabernet Sauvignon.

9. Copper and Iron – Control of Oxidation

Copper and iron salts can sometimes be used in small amounts to control oxidation in wine. Oxidation can cause a wine to develop off-flavors, so these metals help prevent it by binding with oxidizing agents and reducing their activity.

How it affects you: Generally, these metals are used in such small quantities that they don’t affect the wine’s flavor. However, improper handling or excessive amounts can lead to metallic flavors or unpleasant reactions.

10. Potassium Sorbate – Preventing Further Fermentation

Potassium sorbate is often used to prevent unwanted fermentation in wines that have already been bottled. This is especially common in sweet wines, where fermentation could resume due to residual sugar in the bottle.

How it affects you: Potassium sorbate is a preservative that doesn’t usually affect the taste, but some wine drinkers may notice a slight reduction in the freshness or flavor of wines treated with this compound.

Conclusion:

While it’s true that many chemicals and additives are used in winemaking, most of them play a specific role in preserving the wine’s quality, enhancing its flavor, or ensuring consistency. If you’re concerned about what’s in your wine, look for labels that indicate no added sulfites, vegan-friendly, or organic certification. Understanding the chemicals in your wine can deepen your appreciation of the craft and make you a more informed wine drinker.