Is There Protein in Wine? What You Need to Know

November 23, 2025 •

4 min read

Did you know that a standard glass of wine contains a negligible amount of protein, often less than 0.1 grams? While not a dietary source of protein, its presence is a major factor for winemakers concerning clarity and stability during production.

Quick Summary

Wine contains minimal protein, mainly from grapes. This protein is typically removed during winemaking through a process called fining to prevent haze and ensure clarity.

Key Points

Minimal Protein Content: A standard serving of wine contains a nutritionally insignificant amount of protein, typically less than 0.1 gram.
A Winemaking Concern, Not a Health Food: The primary concern with protein in wine is not nutrition, but its impact on clarity and visual stability, especially in white and rosé wines.
Protein Haze Formation: Proteins, largely from grapes, can cause a haze or cloudy appearance by aggregating and precipitating, a process accelerated by heat exposure.
Allergen Risk from Fining: While most protein is removed, some wines use animal-derived fining agents like egg whites (ovalbumin) or milk (casein), which can be allergens and are often labeled.
Sulfites are Not Protein: Sulfites are inorganic salt preservatives and are not related to wine proteins, although some individuals have sensitivities to them.
Check Labels for Allergens: For those with specific allergies, seeking vegan or unfined wines is important, as labeling is required for common allergens from fining agents in many regions.

The Minimal Nutritional Value of Wine Protein

For anyone looking to increase their daily protein intake, a glass of wine will not be helpful. The amount of protein in most wines is so low as to be nutritionally insignificant, typically less than 0.1 grams per serving. This trace amount is not intentionally included for nutritional benefit but is a natural byproduct of the winemaking process. In fact, most wines are actively treated to remove this protein, meaning the final bottle will contain even less. While wine contains some calories, they come almost entirely from alcohol and carbohydrates (sugars), not protein. A person would need to consume an unhealthily large quantity of wine to gain any measurable protein, far exceeding dietary recommendations. Therefore, focusing on sources like lean meats, legumes, or dairy is a far more effective strategy for meeting protein goals.

The Origin and Function of Protein in Wine

The proteins found in wine are not added during production but are naturally occurring compounds. The primary source of protein is the grape itself, particularly during the ripening process, when grapes produce pathogenesis-related (PR) proteins. These proteins act as a defense mechanism for the plant against pathogens like fungi. A smaller amount of protein may also come from the yeast involved in fermentation. In winemaking, these proteins are not welcome from a technical standpoint. They are notorious for affecting the wine's clarity and stability, a phenomenon known as 'protein haze' or 'heat instability'. This haze is a cloudy appearance that can form in bottled wine, especially white and rosé wines, when exposed to heat during storage or transport. To the average consumer, a hazy wine often looks flawed, leading winemakers to prioritize its removal.

The Winemaking Process and Protein Removal

Winemakers use a process called 'fining' to remove unwanted proteins and achieve a clear, stable wine before bottling. Fining involves adding a fining agent to the wine, which binds to the microscopic protein particles. This new complex becomes heavy enough to settle at the bottom of the tank, where it is then filtered out. This process is crucial for preventing the unsightly haze that can form post-bottling. The fining agent of choice can have important implications for consumers with dietary restrictions or allergies.

Comparison of Common Fining Agents


Fining Agent	Type	Origin	Common Use	Vegan-Friendly?	Allergen Risk	Notes
Bentonite	Clay	Volcanic Ash	Removes protein, clarifies white wines	Yes	No	Most widely used; very effective.
Casein	Protein	Milk	Clarifies white wines, reduces browning	No	Yes (Milk)	Found in many dairy products.
Egg Albumin	Protein	Egg White	Reduces astringency in red wines	No	Yes (Egg)	Historically common, now often labeled.
Isinglass	Protein	Fish Bladder	Clarifies white wines, enhances fruit aromas	No	Yes (Fish)	Used primarily for white wines.
Pea Protein	Protein	Plant-based	Vegan alternative, various clarifying uses	Yes	No (Generally)	Growing in popularity for vegan wines.

Allergens and Other Considerations

For the vast majority of people, the minimal protein in wine is not a concern. However, for those with allergies to milk, eggs, or fish, the potential for trace amounts of fining agents to remain in the finished product is a serious issue. Regulatory bodies in many regions, including Australia and the EU, require winemakers to declare the use of common allergens on their labels. This is why many wine labels specify 'Contains Milk' or 'Contains Egg.' While producers ensure fining agents are filtered out, labeling covers the possibility of minute traces remaining. It is important to note that a wine's protein content and its sulfite content are entirely unrelated. Sulfites are inorganic salts used as preservatives and are not proteins. A sulfite sensitivity is distinct from a protein allergy, though both can cause adverse reactions.

Other Factors Influencing Wine Protein Instability

Besides the proteins themselves, several other factors can influence the stability of a wine and its propensity to develop a haze. These include:

Temperature fluctuations: Heat exposure is the primary trigger for protein unfolding and aggregation, leading to visible haze.
Wine pH: Lower pH levels can affect protein stability.
Alcohol content: Higher ethanol concentrations can affect protein folding and increase the risk of haze.
Phenolic compounds: The presence of polyphenols and tannins can interact with proteins and influence haze formation.
Polysaccharides: These large sugar molecules can either prevent or enhance protein precipitation depending on their interaction.

Conclusion: A Matter of Winemaking, Not Nutrition

In summary, while there is a small amount of protein in wine, it is not a meaningful source of dietary protein. The protein originates from the grapes and is primarily a concern for winemakers because it can cause a visual defect known as haze. Through the centuries-old process of fining, winemakers clarify their product, often using protein-based agents like egg whites or milk products. This process creates a potential allergen risk for sensitive consumers, who should seek wines that specify they are unfined or made using vegan alternatives like bentonite. So, the next time you pour a glass of clear wine, you can thank the fining process for removing the very proteins that were never intended to be part of your nutritional plan.

For more in-depth information on the technical aspects of winemaking and allergen labeling, the Australian Wine Research Institute is an excellent resource.

Frequently Asked Questions

No. A typical glass of wine contains less than 0.1 gram of protein, a negligible amount with no dietary significance.

The protein in wine originates from the grapes themselves, primarily through pathogenesis-related (PR) proteins, and to a lesser extent from yeast used during fermentation.

Winemakers remove protein to prevent protein haze, or cloudiness, that can form in the bottle. This ensures the wine remains clear, stable, and visually appealing, especially in white and rosé varieties.

Fining is a clarification process where an agent is added to the wine to bind with and precipitate undesirable particles, including proteins and tannins. This allows for easier filtration before bottling.

No. Traditional fining agents can include animal products like egg whites, milk casein, or fish gelatin. Vegan wines use non-animal-based agents like bentonite, a type of clay.

Yes, though it is rare. Allergies are possible to grape-derived proteins or to protein-based fining agents. A true wine protein allergy is different from an intolerance to histamines or sulfites.

Both contain very low levels. Red wine is fermented with grape skins, which can introduce more protein initially, but the final bottled product for both types generally has minimal protein after fining.

No. Sulfites are inorganic salts used as a preservative, while proteins are complex organic molecules. They are chemically distinct compounds, though both can cause adverse reactions in sensitive individuals.