Hops and hop products are subject to aging processes which depend upon the conditions during storage and in the surrounding environment. In order to assess the freshness of hop products, analytical methods capable of detecting aging compounds are necessary. However, since the existing methods record changes in the spectrum of the constituents in hops, they are only applicable to conventional products. The closer a product is in chemical composition to hop cones, the more relevant the applied evaluation criteria are.
The transformation of bitter substances into iso-α-acids is only desirable in isomerized products. Therefore, it is not appropriate to evaluate this kind of product by the presence of isomerized compounds in it.
This method describes how to determine the hop storage index (HSI) in hops and hop products.
Hops and hop products intended for use in beer brewing or elsewhere in the food industry
The oxidative degradation of the α-acids and β-acids in hops and conventional hop products is determined using a spectrophotometer. The HSI can be referenced in addition to or together with the spectrophotometric method for determining the α-acids and β-acids in hops outlined under R-300.04.110 α-Acids and β-Acids in Whole Hops and Hop Products – Spectrophotometric Method.