The effect of hop beta acids oxidation products on beer bitterness.

Abstract

Instability and tendency to oxidation depending on conditions is a dominant property of hop beta acids . This property has an impact on both the hop storage and the beer brewing process . Approximately one half of the amount decomposes in the air at room temperature in the course of one month . After 6 months the rate of degradation is more than 90% . The dynamics of the decomposition is much slower in leaf hops, primarily during the first 6 months of storage . Changes of beta acids during ageing explain why the bittering potential of old hops does not decline proportionally to the alpha acid loss . A large share of degradation products are formed by cyclization of prenyl side chains of beta acids (tricyclolupulones and hydroxytricyclolupulones) . Beers hopped by oxidation products of beta acids at the rate of 20 g/hl showed distinct sensorial bitterness that was not unpleasant and clinging . The bittering potential of oxidation products of beta acids reaches approximately 35-40% of the bitterness of iso-alpha acids .Instability and tendency to oxidation depending on conditions is a dominant property of hop beta acids . This property has an impact on both the hop storage and the beer brewing process . Approximately one half of the amount decomposes in the air at room temperature in the course of one month . After 6 months the rate of degradation is more than 90% . The dynamics of the decomposition is much slower in leaf hops, primarily during the first 6 months of storage . Changes of beta acids during ageing explain why the bittering potential of old hops does not decline proportionally to the alpha acid loss . A large share of degradation products are formed by cyclization of prenyl side chains of beta acids (tricyclolupulones and hydroxytricyclolupulones) . Beers hopped by oxidation products of beta acids at the rate of 20 g/hl showed distinct sensorial bitterness that was not unpleasant and clinging . The bittering potential of oxidation products of beta acids reaches approximately 35-40% of the bitterness of iso-alpha acids .