Isomerised hop products are chemically modified products which are not permitted for use in Germany due to the beer purity law (Reinheitsgebot). They can be divided into two groups: firstly, products used in the brewhouse (kettle products), and secondly post-fermentation products.
Products intended for the brewhouse are either isomerized hop pellets or isomerized hop extracts (kettle extract). The post-fermentation products, as the name suggests, are used after fermentation and are usually dosed into the finished beer during the filtration stage.
Another type of product, the hop aroma products, can similarly be divided into two groups – products used in the brewhouse, and post-fermentation aroma products.