Application Method

pH Measurement of Soft Drinks

Application Method

The Correct Sensor for Accurate pH Measurements of Soft Drinks

pH of soft drinks
pH of soft drinks

Frequently monitoring the pH of soft drinks is necessary throughout the manufacturing process, right from measuring the pH of water used for soft-drink manufacturing up to the finished beverage. When conventional glass sensors are used, they are highly susceptible to damage during use, especially when different spot checks are required. Inconsistencies in readings and prolonged response times are a few additional limitations that conventional sensors face while measuring the pH of soft drinks and hence are not suitable for the analysis. Correct sensor selection is therefore necessary for accurate measurements.

METTLER TOLEDO's InLab® Versatile Pro is an economical pH sensor with a replaceable ceramic junction that is tailor-made for this application. It is a perfectly suited sensor for routine pH measurements during carbonated beverage production, providing rapid and precise pH results with minimal user effort. Its body is made of polysulfone for robustness and hence can be extended for both in laboratory and at-line applications in harsh production environments.

For more details about this sensor, read our application note on the pH measurement of soft drinks.

The following sections highlight the importance of measuring the pH of soft drinks, along with relevant information about soft drink manufacturing.

What are soft-drinks?

Soft drinks are beverages that contain water, sugar and flavoring, and constitute the most prominent category in the non-alcoholic beverage sector. Though originally derived from mineral-rich spring water, they are now usually carbonated by bubbling in carbon dioxide (CO2) gas for added fizz. As their manufacturing process closely resembles that of other popular non-alcoholic beverages such as energy drinks and iced tea, the trade association for US beverage producers, formerly known as the National Soft Drink Association, has changed its name to the American Beverage Association so as to accommodate the expanded range of products.

Why measuring the pH of soft drinks is important?

The pH of soft drink is responsible for imparting the right flavor and aroma to the drink. Soft drink manufacturers have to adhere to stringent guidelines set by regulatory agencies to ensure the consistency and quality of their product. Meeting these requirements is not only essential to comply with health guidelines, but simplifies production and helps manufacturers to maintain consistency in the flavor and color of the final product. This involves the frequent monitoring of pH at different stages of soft drink manufacturing. The concentration of CO2, responsible for imparting the fizz, is also one of the important factors affecting pH. As sweetness and tartness of these beverages determine their overall flavor, pH consistency is critically important to brand loyalty.

How are soft drinks carbonated and what is the pH of soft drinks?

Carbonation is a process wherein pressurized CO2 is passed through water, producing carbonic acid along with dissolved CO2 gas. Most carbonated drinks, which are approximately 94% water, have pH around 2.5 to 3.5, and hence are highly acidic. However, the partial pressure of CO2 has an important relationship with pH. The typical soft drink is carbonated at 2.5 atmospheric units (atm), resulting in a high concentration of dissolved CO2 and an acidic medium of pH 3.7. At normal atmospheric conditions, dissolved CO2 is low and soft drink pH is now closer to neutral (around 5.7). The amount of carbon dioxide pressure also depends on the type of soft drink.