Which characteristic is least likely to be impacted by the addition of hops?

The characteristic that is least likely to be impacted by the addition of hops is mouthfeel. Hops primarily contribute bitterness, aroma, and flavor when added to beer, depending on when they are added during the brewing process and how they are treated.

Bitterness comes from the alpha acids in hops, which are released during the boiling process, thus creating a noticeable impact on the beer's balance and taste profile. Aroma and flavor from hops can vary significantly with the timing of their addition, especially when added late in the boil or during fermentation, where volatile oils contribute to aromatic and flavor characteristics.

Mouthfeel, on the other hand, is primarily influenced by the malt characteristics, sugar content, carbonation levels, and other physical aspects of the beer rather than the hop additions. While hops can contribute some astringency, their main function does not include altering the mouthfeel in a significant way compared to other components of the brew. Therefore, mouthfeel is the least likely characteristic to be affected by hops compared to bitterness, aroma, and flavor.