A Method of Detection for Residual Isinglass in Filtered and Cask‐Conditioned Beers

Isinglass has been used as a clarification agent in brewing for many years. However, recently its use has come under scrutiny. Due to concerns about food intolerance and food allergies, the EU and other government bodies have introduced legislation obliging food producers to declare those ingredients, additives and process aids, which are listed as allergens, on product labels. One of the affected products that is used in the brewing industry is isinglass. Within the EU, the brewing industry has objected to its inclusion as there is no evidence to suggest it is involved in food allergies. Due to this objection, isinglass has been granted exemption from the regulations for two years, to November 2007. During this time the industry must prove that isinglass is non-allergenic. This paper presents a simple and sensitive method for detecting the presence of isinglass in beer. The method involves hydrolysing beer samples with acid and measuring levels of hydroxyproline. This amino acid is found in isinglass but not in brewing raw materials. This method will be of use in any investigations involving isinglass. Data are presented showing how the method can be used to test for the presence or absence of isinglass in filtered and cask-conditioned beers.