Effect of storage on the brewing properties of tropical hop substitutes

Abstract

Tropical hop substitutes from Utazi (UTZ) Gongronema latifolium, Bitter Cola (BTC) Garcinia kola bitter leaf (BTL) Vernonia amygdalina and a blend (1:1.41:2.89) of the three (HSB) respectively, were produced. Stability studies were carried out to predict their suitability for brewing after one to six months storage at 5±1oC and 27±1oC respectively. These were determined using the level of reduction in their á-acid, iso-á-acid, soft resin, analytical bitterness and degree of utilization levels. Result showed that there was a general reduction of between 10% to 30% in these parameters. However, the (HSB) recorded lower losses than BTC, BLF, and UTZ. Also the samples were more stable at 5±1oC than at 27±1oC. Samples treated with Ca(0H)2 had lower rate of decrease in stability with percentage loses of between 5% to 15% recorded in all the samples. Pertinently, these levels of reduction were comparable to the level of losses reported in conventional temperate hops (Humulus lupulus) stored under similar conditions. Therefore, the tropical hop substitutes when stored at 5±1oC to 27±1oC still retained an acceptably high level of their hops properties that is adequate for beer brewing.