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®)
Iso alpha acids are the native bittering compunds in traditionally hopped beer. Isohop is used to improve utilisation or to improve bitterness control. This product is a pure aqueous solution of iso alpha acids. Typically supplied at a standard concentration of 30% w/w. It is usually described as having a "clean" bittering profile.
Redihop® is an aqueous solution of rho-iso-alpha-acids which are light stable and are therefore useful in the manufacture of beer to be packaged in green or clean glass bottles. It is typically described as having a "clean and smooth" bitterness profile.
Tetrahop® is an aqueous solution of tetrahydro-iso-alpha-acids. While providing bitterness, the main benefit is come from its ability to improve head retention and cling in beer at concentrations around 3 - 5 ppm. It may also be used in light stable brewing. The bitterness profile is typically described as "harsh" and is often used in combination with other products.