Which fining agent is commonly added during the boil?

Irish Moss is commonly added during the boil as a fining agent to help clarify the beer by reducing haze. It is a type of seaweed that contains carrageenan, which effectively helps to coagulate proteins and other particles that might cause haziness in the finished beer. When added during the boil, Irish Moss assists in promoting the precipitation of proteins that could otherwise lead to cloudiness, making it easier for them to settle out during fermentation.

In the brewing process, adding a fining agent like Irish Moss at this stage is beneficial because it allows the proteins and polyphenols to bind together and drop out of the solution as the wort cools. This results in a clearer beer with better overall appearance and stability.

Other fining agents mentioned may have different properties and best practices for usage. Gelatin is typically added after fermentation, Whirlfloc (similar to Irish Moss but in a tablet form) can be used during the boil but is not as traditional as Irish Moss, and Bentonite is also used primarily after fermentation to help clarify the beer by adsorbing particles but is not added during the boil like Irish Moss.