Bittering in beer is provided mainly by the Isomerised alpha acids. These can be formed during the boiling process from the alpha acids present in hops, hop pellets or CO2 extract.
Products in this category include Ike, iso pellets, and the advanced bittering range of products (Isohop®, Redihop®, Tetrahop®)
The compounds of main interest to the brewer can be extracted from hops using liquid carbon dioxide as a non polar and non toxic solvent. This produces a very stable, highly viscous liquid, known as CO2 extract. This product is usually added to the brew kettle during the boil.
IKE Isomerised Kettle Extract
This product is CO2 extract which has been processed to isomerise the alpha acids present. It is also added to the brew kettle during the boil. The main added benefit is improved utilisation of the alpha acids.