Trub or hot trub is the excess material left in the boil kettle after the wort has been transferred. Boil kettle trub typically consists of hop matter, grain fiber, tannins, and the dense proteins known as the hot break that combine during the first 15 minutes of the boil, and ultimately drop to the bottom of the kettle. It is recommended that the trub not be transferred to the fermenter, as it may impart off flavors on the finished beer.

 

The trub that was left over in the boil kettle after the boil took place and the wort was transferred into fermenters.

Boil Kettle Trub

Boil Kettle Trub