How is carbonation in beer quantified?

The correct answer, "In volumes of CO2," refers to a standardized method of quantifying carbonation in beer. This measurement indicates the amount of carbon dioxide present in the beer relative to the volume of liquid. Specifically, one volume of CO2 means that the amount of CO2 dissolved in the beer is equivalent to the volume of the beer itself. For instance, if a beer is said to be carbonated to 2.5 volumes, it contains 2.5 times the amount of CO2 compared to the volume of the liquid.

This method is widely used in the brewing industry because it provides a clear and consistent way to assess carbonation levels, which can significantly affect the beer's mouthfeel, aroma, and overall drinking experience. Understanding carbonation in terms of volumes allows brewers to maintain quality and consistency across different batches of beer.

In contrast, measuring pressure in the keg or considering the amount of sugar added may provide some information about carbonation, but they do not give a precise quantification of dissolved CO2 in the finished beer. Additionally, measuring in grams per liter is not a standard way to express carbonation and can lead to inconsistency and confusion in the context of brewing and style guidelines.