The Importance of pH In Wine-Making


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When making wine, pH measures the acidity of the wine, determining its ripeness. A wine that has a low pH level (more acidic) typically tastes sour and dry, while a wine that is more alkaline (has a high pH) will taste flat and lack freshness due to increased bacterial growth. The pH of most wine is between 3.0 and 4.0; white wine usually has a pH level of 3.0 to 3.4, and red wine is between 3.3 to 3.6.

Wine lovers know that the perfect glass of wine is an experience like no other. But have you ever stopped to think about what goes into creating that rich, complex flavor that you love? 

One crucial factor in winemaking is pH. pH is a measurement of acidity or alkalinity, and it plays a vital role in determining the quality of the wine’s final product. From the grapes to the fermentation process, pH levels must be carefully monitored and controlled to produce a wine that is both delicious and stable. 

Whether you are a seasoned winemaker or a curious wine enthusiast, this article will provide valuable insights into the world of winemaking and the science behind it.

Understanding pH

pH stands for ‘potential of hydrogen’ and indicates if a solution is acidic or a base. The pH scale ranges from 0 – 14, with 7.0 being neutral. Substances with a lower pH are acidic, while those with a higher pH are basic or alkaline. Understanding pH levels is essential in various fields, including chemistry, agriculture, medicine, and environmental science.

Acids are substances that have a pH below 7.0. They release hydrogen ions (H+) when dissolved in a solution, and are known for their sour taste and corrosive nature. On the other hand, bases (or alkalis) have a pH above 7.0. Alkaline solutions release hydroxide ions (OH-) when dissolved in water, and generally have a bitter taste and slippery texture. 

The pH scale is logarithmic, meaning that each unit represents a ten-fold difference in acidity or alkalinity. For instance, a solution with a pH of 3.0 is 10x more acidic than one with a pH of 4.0 and 100x more acidic than one with a pH of 5. Similarly, a solution with a pH of 11.0 is ten times more basic than one with a pH of 10.0 and 100x more basic than one with a pH of 9.0.

Knowing the pH level of a substance is crucial in many applications, including the production of beverages such as wine and beer. In the context of winemaking, pH is used to measure the concentration of hydrogen ions (H+) present in the wine, which is indicative of the overall acidity of the wine.

What Role Does pH Have In Winemaking?

The pH of a wine can significantly influence its taste, aroma, color, and stability, making it a crucial element to monitor and control throughout the winemaking process. A wine’s pH can affect its microbial stability, which in turn impacts its shelf life and susceptibility to spoilage. 

Additionally, pH levels can influence the rate of fermentation, the effectiveness of certain additives, and the overall mouthfeel of the final product.

A wine with a low pH is more acidic and has a crisp, refreshing taste, while a wine with a high pH is less acidic and has a softer, rounder taste. pH also affects the color and stability of wine.

Wines with a high pH are more prone to oxidation and spoilage, while wines with a low pH are more stable and have a longer shelf life. pH also affects the growth of bacteria and yeast in wine. Some bacteria and yeast thrive in low pH environments, while others prefer higher pH levels. Winemakers must carefully control the pH of their wines to ensure the desired taste, stability, and microbial growth.

Acidity In Wine-Making 

Wine acidity refers to the level of acid present in wine, which is a key factor in determining its flavor. Acids in wine include tartaric, malic, lactic, and citric acid. These acids are responsible for the sour taste of wine and contribute to its crispness, freshness, and balance.

The Science Behind Wine Acidity

The acidity in wine comes from the grapes used to make the wine. The level of acidity in grapes depends on factors such as climate, soil, grape variety, and ripeness. Grapes grown in colder climates typically have higher acidity levels than grapes grown in much warmer climates.

During the winemaking process, the acidity of the grapes is further influenced by factors such as fermentation, malolactic fermentation, and aging. 

How Does pH Change Throughout The Winemaking Process?

Throughout the winemaking process, the pH can change significantly due to various factors, such as grape variety, fermentation, and aging.

The pH of a wine starts with the grapes themselves. As grapes ripen, their acidity levels decrease, increasing pH. The timing of the grape harvest is critical for winemakers, as they must balance the desired pH levels with other factors such as sugar content, titratable acidity, and tannins.

During alcoholic fermentation, the yeast Saccharomyces cerevisiae metabolizes sugars in the grape juice, producing ethanol and various acids, such as succinic acid. This process generally results in a slight decrease in pH, as the production of acids increases the overall acidity of the wine.

Malolactic fermentation is a secondary fermentation process that converts malic acid, a stronger acid, into lactic acid, a weaker acid. This conversion increases pH, as the wine becomes less acidic overall.

Cold stabilization is a process used to prevent the formation of tartrate crystals in bottled wine, which can occur when wines are exposed to cold temperatures. The process involves chilling the wine to promote the precipitation of tartaric acid, which in turn reduces the overall acidity of the wine. Depending on the initial pH of the wine, cold stabilization can either increase or decrease pH levels.

Ideal pH Ranges For Wine Varieties

Different wine types have different ideal pH ranges, depending on their flavor profile and structure. White wines typically have a higher pH than red wines, ranging from 3.0 to 3.4, while red wines typically have a pH of 3.3 to 3.6. Sweet wines tend to have a lower pH, while sparkling wines have a higher pH due to their carbonation.

Winemakers must carefully monitor the pH of their wines during the winemaking process to ensure the desired flavor and structure. For example, a white wine with a pH that is too high may taste flabby (lacking structure) and lack acidity, while a red wine with a pH that is too low may taste tart and harsh.

The Effects Of pH On Wine Quality

As mentioned, the pH of a wine can have a significant impact on its overall quality, from its taste and aroma to its stability and shelf life. By carefully monitoring and controlling pH levels throughout the winemaking process, winemakers can produce wines with the desired balance of acidity and alkalinity, resulting in a final product that is both delicious and long-lasting!

Flavor & Aroma 

A wine’s pH can have a profound effect on its flavor profile. Wines with a lower pH tend to taste more acidic and tart, while those with a higher pH tend to taste smoother and more mellow. This is because acidity is a key component of a wine’s flavor, and the pH level can either enhance or detract from this aspect of the wine. For example, a high-acid wine like Sauvignon Blanc will have a lower pH than a low-acid wine like Chardonnay, which can make it taste more vibrant and crisp.

In addition to affecting the taste of the wine, the pH level can also have a significant impact on its aroma. Wines with a higher pH tend to have more pronounced fruit aromas, while those with a lower pH may have more earthy or mineral notes. This is because certain aroma compounds are more volatile at different pH levels, and these compounds can be either enhanced or suppressed depending on the wine’s acidity. 

For example, a Pinot Noir with a higher pH might have more pronounced cherry or raspberry aromas, while one with a lower pH might have more earthy or mushroom-like aromas.


In general, wines with a lower pH level will have a deeper color than those with a higher pH level. This is because the acidity in the wine helps to stabilize the pigments that give the wine its color. When the pH level is too high, those pigments can become unstable and break down, resulting in a lighter, less vibrant color.

This is particularly true for red wines, which are more sensitive to changes in pH than white wines. Red wines that are too acidic can appear more purple or blue, while those that are too alkaline may have a more orange or brown hue. Of course, the ideal pH level for a wine will depend on many factors, including the grape variety, growing conditions, and winemaking techniques.

Stability & Shelf Life

A wine’s pH level can influence its microbial stability, which is essential for maintaining its shelf life. When the pH level is too high or too low, it can disrupt the natural balance of microorganisms in the wine, leading to spoilage or contamination, and no one wants to drink wine that has gone off. 

Wines with a low pH (higher acidity) are more resistant to microbial spoilage, as most bacteria and fungi struggle to thrive in acidic environments. This natural protection against spoilage helps to extend the shelf life of low-pH wines. 

Conversely, wines with a high pH (lower acidity) are more susceptible to spoilage and may require additional preservatives, such as sulfur dioxide (SO2), to maintain stability.


The pH of a wine can also impact the rate and efficiency of fermentation processes, such as alcoholic fermentation (AF) and malolactic fermentation (MLF).

Yeasts and bacteria involved in these fermentations are sensitive to pH levels, with optimal growth and activity typically occurring within a specific pH range. For example, malolactic bacteria generally require a pH above 3.2 and SO2 levels below 10 mg/L to thrive.

How To Accurately Measure pH In Wine-Making? 

Winemakers use various tools and methods to measure wine acidity and pH levels. One of the most common methods is titration, in which a solution of known concentration is added to the wine until the acid has been neutralized. The amount of solution needed to neutralize the acid is used to calculate the wine’s acidity.

pH can also be measured using a pH meter or pH strips, which provide a quick and easy way to determine the pH of a wine. Alternatively, winemakers can also use a wine acid test kit, which includes all the necessary equipment and instructions to measure wine acidity.

We recommend a pH meter to accurately measure the pH of the wine. These include benchtop pH meters or handheld meters with a reliable pH probe/electrode. When using pH meters, it is essential to regularly calibrate the meter and properly store and maintain the electrode to ensure accurate and reliable measurements.

At Atlas Scientific, we have the perfect solution for monitoring the pH of your wine. With our Consumer Grade pH Meter, you will always have reliable and accurate pH readings. 

How To Adjust The pH Of Wine?

If necessary, winemakers can adjust the pH of a wine to improve its taste, stability, and overall quality

Winemakers have several tools and techniques at their disposal for adjusting wine acidity and pH levels. One of the most common methods is acidification, in which tartaric acid is added to the wine to increase acidity levels.

Another method is deacidification, in which potassium bicarbonate or calcium carbonate is added to the wine to reduce acidity levels. Calcium carbonate reacts with the acid to form calcium tartrate, a harmless salt that can be removed through filtration. Winemakers can also adjust acidity levels by controlling fermentation and aging conditions, such as temperature and duration.

Another method is to blend wines with different acidity levels to achieve the desired balance. For example, a wine with high acidity can be blended with a wine with lower acidity to achieve the desired taste. 

It is essential to perform bench trials on small samples before treating the entire batch of wine, to ensure the desired results are achieved without over-treating the wine.

Factors That Affect Wine Acidity & pH Levels

Several factors can affect wine acidity and pH levels, including grape variety, climate, soil, ripeness, fermentation, malolactic fermentation, and aging.

Grape variety plays a significant role in determining the level of acidity in wine, with some varieties naturally higher in acid than others. Climate and soil can also affect acidity levels, with cooler climates and well-drained soils tending to produce higher acidity grapes.

Fermentation and aging can also affect wine acidity and pH levels. Extended fermentation can reduce acidity levels, while aging can cause some acids to break down or undergo chemical reactions, affecting the wine’s pH. 


Understanding the importance of pH levels and wine acidity is crucial for winemakers and wine enthusiasts alike. Acidity plays a crucial role in determining the taste, structure, and stability of the wine, while pH affects its color, microbial growth, and stability.

By carefully controlling acidity and pH levels, winemakers can create perfectly balanced wines that showcase the unique flavors and aromas of their grapes. Wine enthusiasts can also appreciate the importance of acidity and pH in determining the taste and quality of their favorite wines. With the right tools and techniques, anyone can create perfectly balanced wines that are a delight to the senses.
If you have questions regarding the pH of your wine, or which pH meter to choose, do not hesitate the world-class team at Atlas Scientific.

pH Probes & Sensors

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