Carbonation in soda is primarily measured by checking the pressure inside the sealed container at a specific, known temperature.
Measuring the level of carbonation in a soft drink, which is essentially the amount of dissolved carbon dioxide (CO2), is a crucial step in quality control to ensure consistency and taste. The most common method relies on a fundamental scientific principle: the relationship between dissolved gas, temperature, and pressure.
According to standard practices, carbonation is usually determined in soft drinks by measuring the pressure in the container at a known temperature.
Here's a breakdown of the process:
- Sealed Container: The soda must be in its original, sealed packaging, such as a can or bottle.
- Known Temperature: The temperature of the soda inside the container is carefully controlled and measured. This is vital because the solubility of CO2 in liquid changes significantly with temperature. Colder liquids can hold more dissolved CO2 than warmer ones.
- Pressure Measurement: A specialized instrument is used to puncture the container's closure (while maintaining the seal for pressure) and measure the internal pressure exerted by the CO2 that is not dissolved (the headspace gas) and the CO2 coming out of the solution.
The pressure inside a container (can or bottle) is dependent upon the level of dissolved CO2 and the temperature. A higher pressure at a given temperature indicates a higher level of dissolved carbonation. Manufacturers use charts or calculations based on Henry's Law (which describes gas solubility in liquids) to translate the measured pressure and temperature into the volume of CO2 dissolved in the liquid, often expressed in volumes of CO2 per volume of liquid.
For instance, water at 0°C will dissolve approximately 3.6 grams per liter (g/L) of CO2. This demonstrates how temperature directly impacts how much CO2 can stay dissolved under pressure.
This method provides a quick, reliable, and non-destructive way to assess the carbonation level in every batch of soda produced.
