What unit is used to measure the bitterness of beer?

The correct unit used to measure the bitterness of beer is known as the International Bitterness Unit (IBU). This measurement quantifies the concentration of iso-alpha acids, which are the compounds responsible for the bitter flavor in beer. The method for determining IBU involves assessing the amount of hops and the specific brewing process, as the bitterness can vary significantly depending on these factors.

Understanding the IBU scale is essential for brewers, as it helps them control the degree of bitterness in their final product, allowing for innovation in flavor profiles while maintaining consistency across batches. An IBU measurement can range widely, from low values for lighter beers to much higher values for hop-forward styles like IPAs.

The other options do not accurately represent the standard terminology within the brewing industry for measuring bitterness. While they might resonate with aspects of bitterness measurement, they are not the established unit recognized globally. Thus, the International Bitterness Unit is the correct and widely accepted answer for measuring how bitter a beer is.