Application Note: Ensure Consistent Carbon Dioxide Levels In Soft Drinks

Consistency of carbonation ensures customer satisfaction and loyalty. Many soft drink bottlers determine carbonation by measuring the total pressure and temperature of a beverage. This method to calculate the amount of CO2 is risky because it assumes the only gas present in the drink is CO2, which is often not the case. Air, in varying amounts, is always present in a typical soft drink. The amount of air changes depending on several factors, including source water temperature, incomplete de-aeration and air contamination during production, filtering, and filling.

Measuring the total pressure and temperature is a quick and easy method for determining carbonation. The error in using this method is that it results in an overestimation of CO2 due to the influence of air. Since air is entrained in the water, introduced during syrup agitation and is picked up at the filler, it adds to the total pressure. As the level of air changes over time, so will the measurement of CO2 using a total pressure and temperature method. This causes an inconsistent CO2 result which means soft drink bottlers are not able to precisely control carbonation levels.

Air is made up of oxygen and nitrogen. Oxygen and nitrogen dissolved in a beverage do not have the same texture and feel effect as CO2. Therefore, the measurement of CO2 pressure specifically is a more accurate parameter for the carbonation level, final product quality, and product consistency.