The solubility of nitrogen in the form of N2 is approx. 20 mg/l in water at 20 °C and at 1 bar of pressure.
Still beverages, such as water, juices, iced tea, etc. increase in volume, i.e., in the consumers' favor. Since there is little to no carbon dioxide in these beverages during filling in PET bottles, the bottles are unstable. It is therefore difficult to apply labels to them, and it is problematic to stack them on pallets or to subsequently transport them. This complicates production and logistical planning.
Determination of the dissolved nitrogen (N2) content using heat conductivity in carbonated and non-carbonated beverages that have been nitrogenated
This analysis is suitable for determining the concentration of dissolved nitrogen (N2) in carbonated and non-carbonated beverages that have been nitrogenated.
Dissolved nitrogen in a liquid medium is measured using the same procedure as the CO2 determination, i.e., using heat conductivity.
CO2 is employed as a purge gas in the beverage industry. Therefore, in order to measure nitrogen, the change in thermal activity and CO2 and N2 is used. The thermal conductivity is determined in a small measurement chamber, which in turn is separated from the material being measured by a semipermeable membrane. Diffusion through the membrane changes the thermal conductivity in the measurement chamber.
The gas volume in the measurement chamber is fully replaced in cycles of 10–20 s. The changes in thermal conductivity over time are a measure of the diffusion of N2 through the membrane, which allows the concentration in the medium to be calculated, taking temperature into account.
The calculation for the concentration of N2 is achieved using the change in thermal conductivity in the measurement chamber, also taking the temperature into account.
Since the thermal conductivity of oxygen is similar to that of nitrogen, a second channel may need to be used to compensate for any oxygen in the medium [1].