What impact does high calcium carbonate content have on brewing?

High calcium carbonate content in water used for brewing has a significant impact on the flavor and characteristics of beer, particularly with regards to hop bitterness and astringency. Calcium carbonate acts as a pH stabilizer, and its presence can increase the pH level of the water. A higher pH can lead to increased extraction of certain flavors from the hops, resulting in enhanced bitterness.

Moreover, this elevated pH can contribute to increased astringency in the beer, which is the dry, puckering sensation often felt in the mouth, particularly after consuming certain styles of beer. This effect is particularly notable in beers with substantial hop characteristics, such as IPAs.

In contrast, other options do not accurately represent the role of calcium carbonate. While it can affect how flavors are perceived, it does not soften the flavor profile, increase sweetness, or produce a thicker mouthfeel in the context commonly associated with brewing. Instead, the influence of calcium carbonate primarily pertains to the balance and interplay of bitterness and astringency within the beer.