The Influence of Hop Acid Components on the Phenomenon of Gushing in Various Standard and Non-Alcoholic Beers – Evaluation of Advanced Hop Products under Induced Gushing Conditions

Clearly the occurrence and control of gushing is a critically important quality factor for many brewers. A large number of studies, publications, and presentations have addressed this topic in the past. Efforts to identify gushing promoters have focused on species generated from barley degradation and infestation, and, to a lesser extent hop constituents, among others. The use by brewers of pre-isomerized hop acid products, including isohumulones and reduced forms such as di-, tetra-, and hexa-hydroisohumulones, continues to increase. To date, a comprehensive study to evaluate the potential for these advanced hop products to either promote or suppress the gushing phenomenon has not been reported..

We have undertaken a study to assess the potential impact on gushing for a variety of hop acid products. Research was conducted using forced testing conditions, which included direct dosing into beer with vigorous long-duration shaking. The influence of hop acid identity, hop processing conditions, and dosing levels were investigated. Other factors such as base beer type, alcohol level, and country of origin were also evaluated. It was determined that low- and non-alcoholic beers are particularly susceptible to induced gushing from hop acid components. Results from this work indicate that the formation of potential gushing initiators in advanced hop acid products can be effectively prevented.

BrewingScience - Monatsschrift für Brauwissenschaft, 66 (November/December 2013), pp. 198-204