Potential African Substitutes for Hops in Tropical Beer Brewing

The potential of four selected tropical vegetables, Grongonema\nlatifolium (Utazi), Vernonia amigdalina (Bitter\nleaf), Azadirachta indica (Neem) and Garcinia cola \n(Bitter Kola) as substitutes for hops in tropical beer brewing were\nevaluated. The vegetables were processed into powder by drying at\n50°C for 24 hours (such that they maintained their original\ncolour) and then cooled in dessicator before milling in a hammer mill.\nProximate analysis showed that these vegetables had protein and crude\nfibre values comparable to those of commercial hops. Fat content values\nwere however much higher than those for hops with Grongonema latifolium\nhaving the highest values of 19.10%. Garcinia cola with a total resin\nvalue of 8.24% and an essential oils value of (1.16ml/ 100g) had values\nwhich were significantly different from those of hops. The other three\nhad values comparable to those for hops. Bitterness levels were high\nwhen the vegetables were extracted with organic solvents, than with\ndistilled water. These values however decreased, the longer the storage\nperiod. Losses in bitterness were more when the vegetables were stored\nat ambient temperature than when they were stored at refrigeration or\nfreezing temperatures. Losses in bitterness were more for water\nextracts than for organic solvent extracts.