What is the main characteristic of lupulin?

Lupulin is a crucial component of hops, renowned for its role in brewing. It is a yellow powdery substance found in the cones or flowers of the hop plant and contains the essential compounds that contribute to the flavor, aroma, and bitterness of beer. Specifically, lupulin is where the alpha and beta acids are concentrated. Alpha acids are primarily responsible for the bitterness of beer when boiled, while beta acids contribute to aroma and flavor characteristics.

When hops are added during the brewing process, the alpha acids undergo a transformation through isomerization, which results in the bitterness that balances the sweetness of malt. Therefore, the identification of lupulin as containing these acids highlights its essential function in brewing, making this characteristic a foundational aspect of hop usage in beer production.

The other aspects mentioned in the other options do not directly relate to the fundamental properties of lupulin itself. While it is true that bitterness extracted from hops during boiling plays a significant role in beer flavor, the explicit identification of lupulin as the carrier of alpha and beta acids is a more precise characterization of what lupulin is and what it contributes to brewing.