CO2 hop resin extract is a product developed from the extraction of the hop components that are important to brewers. These are the alpha-acids and essential oils that contribute to beer bitterness, aroma, head retention, and stability. This is different from using pellets or whole leaf hops, as hop resin extract eliminates a great deal of the inert materials that come with pellets and leaf hops, which means less trub in the bottom of the brew kettle.

John Kimmich, Co-owner and Brewer of The Alchemist Brewery famous for Heady Topper & Focal Banger is constantly working to improve his beers. One of the improvements was the use of only hop extract in the boil. John has apparently been heard to say "No hops in my kettle".

Hop extract is designed to be used during the boil. That's because the alpha acid extraction is the same for hop resin extract as it is for whole hops and pellets and the hop additions can still be staggered throughout the boiling process. Early kettle additions (60-90 minutes of extract/boil time) are used to achieve IBU's in beer and will typically lead to the isomerization of 35% utilization. Adding the hop extract later during the kettle boil will result in various specific flavor and aroma contributions.