The Role Of CO2 In Wine Production


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Carbon dioxide (CO2) plays a crucial role in the production of wine. During the fermentation process, yeast converts sugar into alcohol and releases CO2 as a byproduct. This release of CO2 is what gives the wine its characteristic fizz and bubbles in sparkling wines. In still wines, however, the CO2 is allowed to escape during fermentation, resulting in a still and non-effervescent wine. CO2 also helps to preserve freshness and prevent oxidation in wine. Winemakers carefully control the amount of CO2 present in the wine to achieve the desired level of carbonation and enhance the overall flavor profile with a CO2 meter.

Wine production is a fascinating process that involves various factors contributing to the final product’s flavor, aroma, and quality. Among these factors, carbon dioxide (CO2) plays a significant role. From fermentation to preservation, CO2 influences different stages of wine production.

In this article, we will explore the impact of CO2 in winemaking, its role in fermentation, and the methods used to measure and manage its presence.

The Significance of Carbon Dioxide in Wine

Carbon dioxide (CO2) plays a significant role in the production of wine. While most people associate CO2 with the bubbles in sparkling wines, its importance goes beyond just adding fizz. 

CO2 is a natural byproduct of the fermentation process that converts grape juice into wine. During fermentation, yeast consumes the sugar in the grapes and produces alcohol and CO2 as a result. This release of CO2 is what gives wines their characteristic flavors and textures.

The presence of CO2 in wine is crucial for several reasons. Firstly, it acts as a preservative, helping to protect the wine from oxidation and spoilage. When CO2 dissolves in wine, it creates a protective layer that prevents oxygen from coming into contact with the wine. This is particularly important during the aging process, as exposure to oxygen can cause the wine to lose its flavors and aromas. 

Additionally, CO2 helps to maintain the freshness and vibrancy of the wine by preventing the growth of bacteria and other harmful microorganisms.

CO2 also contributes to the sensory experience of drinking wine. When CO2 is dissolved in wine, it forms tiny bubbles that create an effervescent sensation on the palate. This effervescence can range from a gentle tickle to a lively fizz, depending on the amount of CO2 present in the wine. In sparkling wines, such as Champagne or Prosecco, the high levels of CO2 create a more pronounced and enjoyable effervescence. This adds to the overall enjoyment and complexity of the wine, making it a popular choice for celebrations and special occasions.

Furthermore, CO2 plays a role in enhancing the aromas and flavors of wine. When CO2 is released from the liquid, it carries volatile compounds with it, which are responsible for the wine’s bouquet and taste. These compounds include fruity esters, floral notes, and subtle nuances that contribute to the overall character of the wine. Without the presence of CO2, wines would lack the aromatic intensity and depth that makes them so enticing.

Carbon Dioxide & Wine Fermentation 

The natural production of CO2 in wine production is a result of fermentation. During fermentation, yeast produces CO2 as a natural result of converting sugars into alcohol. This process occurs in both red and white wines, although the phenolic transformation can affect the flavor of white wines differently.

When grapes are harvested and crushed, the sugars in the grapes are exposed to yeast, which is naturally present on the grape skins. These yeast cells consume the sugars and produce alcohol and CO2 as byproducts.

During the fermentation process, the CO2 produced by the yeast gets trapped in the wine, giving it its characteristic effervescence. This is why some wines, such as sparkling wines and champagne, have bubbles. In these types of wines, the winemaker intentionally allows the CO2 to remain in the bottle, creating a delightful fizz when the wine is poured.

In addition to contributing to the bubbles in sparkling wines, CO2 also plays a role in enhancing the overall taste and aroma of the wine. This is particularly true for young wines that have recently undergone fermentation. The presence of CO2 can enhance the fruity and floral notes in the wine, making it more enjoyable to drink.

Carbon Dioxide & Carbonic Maceration

Carbonic maceration is a unique winemaking technique where grapes ferment intact, creating a low-tannin, fruity wine. It is most commonly associated with the production of Beaujolais wines from the Gamay grape in France. CO2 is used to create an anaerobic environment, kickstarting numerous mini-fermentations within each grape. In this process, whole clusters of grapes are placed in a sealed container, which is then filled with carbon dioxide. The weight of the grapes causes some of them to burst, releasing their juice and initiating fermentation within the individual grapes. 

As the fermentation progresses, the CO2 produced creates an anaerobic environment, preventing the growth of yeast and bacteria that typically contribute to traditional fermentation.

The result of carbonic maceration is a wine that is known for its vibrant fruit flavors, low tannins, and light body. These wines often exhibit intense aromas of fresh berries, cherries, and floral notes. The lack of tannins makes them very approachable and easy to drink, even when young. 

While carbonic maceration is most commonly associated with Gamay wines, it can also be used with other grape varieties. Some winemakers choose to incorporate this technique into their winemaking process to add complexity and enhance the fruitiness of their wines. 

Fermentation Control In Wine Production

One way to control fermentation and manage CO2 levels is through temperature regulation. Yeast is a living organism, and its activity is influenced by temperature. By adjusting the temperature during fermentation, winemakers can slow down or speed up the process, which directly affects the production of CO2. Lower temperatures result in slower fermentation and less CO2 production, while higher temperatures can cause a more rapid fermentation with increased CO2 release. To accurately measure temperature in wine production you can use a temperature sensor.

Another method of controlling CO2 levels is through proper grape selection and sorting. Different grape varieties have varying levels of sugar content, which directly impacts the amount of CO2 produced during fermentation. By carefully selecting grapes with balanced sugar levels, winemakers can ensure a more controlled fermentation process and avoid excessive CO2 production. Additionally, thorough grape sorting removes any damaged or unripe grapes that may contribute to higher levels of CO2.

As a winemaker, you can also use various fermentation vessels and techniques to control CO2. For example, open-top fermenters allow for better CO2 release and prevent excessive build-up. Additionally, regular punch-downs or pump-overs during fermentation help release trapped CO2 and improve the overall quality of the wine.

CO2 Measurements & Monitoring In Wine Production

Accurately measuring CO2 levels is crucial for ensuring the quality and consistency of wines. It helps winemakers monitor fermentation progress, control flavors, and prevent safety hazards associated with high CO2 concentrations.

It is also critical to follow the proper permissible exposure limits. Occupational Safety and Health Administration (OSHA) has established permissible exposure limits for CO2 in wineries. These limits ensure worker safety and include PEL (5,000 PPM), STEL (30,000 PPM), and IDLH (50,000 PPM) levels.

You also need to monitor CO2 so you follow the correct ventilation and safety measures. Proper ventilation and fresh air circulation are essential in wineries to prevent the accumulation of CO2 in confined spaces. Regular testing of CO2 levels, hazard communication training, and adherence to confined space protocols are vital.

How To Measure CO2 Levels In Wine?

Most commonly, CO2 meters are used to measure CO2 levels in wineries and fermentation areas. These devices provide real-time data on CO2 concentrations, allowing you to monitor and adjust fermentation conditions accordingly.

A CO2 meter can also be helpful for wine enthusiasts who want to understand the characteristics of different wines.

To measure the CO2 levels in wine using a CO2 meter, you will first need to prepare a sample of the wine. This can be done by pouring a small amount of wine into a glass or container. It’s important to note that the wine should be at room temperature before taking the measurement.

Next, you will need to turn on the CO2 meter and allow it to warm up for a few minutes. Once it is ready, you can simply dip the sensor end of the meter into the wine sample. The meter will then display the CO2 levels in parts per million (ppm) or grams per liter (g/L). 

If your results are in ppm, they can easily be converted to g/L with the following equation: 1 part/million (ppm) = 0.000998859 gram/liter

Alternative Methods To Measuring CO2 In Wine

Some non-invasive techniques, such as laser-based spectroscopy, are being explored for measuring CO2 levels in wine production. These methods offer the advantage of continuous monitoring without the need for physical contact with the wine.

In addition to onsite measurements, winemakers may send samples to laboratories for precise CO2 analysis. Laboratory analysis provides detailed information about the wine’s CO2 content, helping winemakers make informed decisions during production.

Typical CO2 Levels Of Wine

Before we go into the common CO2 levels in wine production, it is important to note that different types of wines have different optimal CO2 levels. For example, sparkling wines typically have a higher CO2 level compared to still wines. Also, personal preferences can play a role in determining the ideal level of carbonation in wine.

It’s important to note that not all wines have significant levels of CO2. Most still wines have very low levels of dissolved CO2, which is intentionally removed during the winemaking process. This is done through a process called degassing, where the wine is agitated to release any remaining CO2 before it is bottled. Still white wine typically has a CO2 level of 0.5-1.8 g/L, and still red wines 0.5-1.0 g/L. As for sparking wines, CO2 can reach levels up to 11.8 g/L, yet most sparkling wines are bottled nearer 9 g/L.

Problems With Too Much CO2 In Wine

Have you ever poured yourself a glass of wine, only to find it fizzing like a soda? If so, you may have experienced the problem of too much CO2 in your wine. When too much CO2 is present, it can lead to several problems that can affect the taste and overall quality of the wine.

One of the main issues with excessive CO2 in wine is that it can give the wine a fizzy or sparkling texture. While some wines, such as Champagne and Prosecco, are intentionally made to be sparkling, most wines are meant to be still. The presence of excessive CO2 can create an unwanted sensation in the mouth, making the wine feel prickly or even slightly painful to drink. This can detract from the enjoyment of the wine and make it difficult to fully appreciate its flavors and aromas.

Another problem with too much CO2 in wine is that it can mask or mute its true flavors. When CO2 is present at high levels, it can create a barrier between the wine and our taste buds, preventing us from fully experiencing its complexity and nuances. This can be particularly frustrating for wine enthusiasts who appreciate the subtle differences in flavor profiles between different grape varieties and regions. Additionally, excessive CO2 can also interfere with the release of aromatic compounds in the wine, further diminishing its overall sensory appeal.

Excessive CO2 can also cause problems during the storage and transportation of wine. The pressure from the trapped gas can cause corks to pop out or bottles to explode, leading to potential loss of product and damage to surrounding bottles. In addition, the presence of excessive CO2 can accelerate the aging process of wine, causing it to deteriorate more quickly than desired.

This is why winemakers carefully monitor and control the fermentation process to ensure that the right amount of CO2 is produced.

Problems With Too Little CO2 In Wine

One of the main issues with too little CO2 in wine is the lack of effervescence. Carbonation adds a delightful fizziness to sparkling wines and certain white wines, creating a refreshing and lively mouthfeel. Without enough CO2, these wines can feel flat and dull on the palate, losing their signature crispness. The absence of bubbles also affects the visual appeal of the wine, as the effervescence adds an attractive sparkle to the glass.

Another problem that arises from insufficient CO2 in wine is the impact on the aroma. The carbonation helps release and carry the aromatic compounds in wine, enhancing the bouquet and making it more pronounced. When there is not enough CO2 present, these aromas can become muted and less vibrant, diminishing the overall sensory experience. Aromas play a crucial role in our perception of taste, so without the proper level of carbonation, the wine may lose some of its complexity and character.

CO2 also serves as a natural preservative in wine. It acts as a barrier against oxygen, preventing oxidation and spoilage. In wines with low levels of CO2, there is an increased risk of exposure to oxygen, which can lead to unwanted chemical reactions and changes in flavor. This can result in a wine that tastes flat, stale, or even vinegary.


Carbon dioxide is an essential component in the production of wine. It not only acts as a preservative, but it also contributes to the sensory experience and overall quality of the wine. From protecting against oxidation to enhancing aromas and flavors, CO2 plays a significant role in making wine a truly enjoyable beverage. So, the next time you raise a glass of wine, take a moment to appreciate the significance of carbon dioxide in creating that perfect sip.

If you want to know more about CO2 in beverages or what CO2 meter we recommend for measuring your drinks, do not hesitate to contact the world-class team at Atlas Scientific.

CO2 Sensor

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