Production of barley malt beer using Gesho (Rhamnus priniodes) in Ethiopia
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Date
2015-06
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Addis Ababa University
Abstract
Beer is widely brewed in Ethiopia. The quality may deteriorate by oxidation. Determination of profile of antioxidant activity in Beer, and bitterness of Gesho are important. Therefore, the objective was to evaluate the suitability of Rhamnus prinoides (Gesho) for beer production in Ethiopia. Beer fermentation was carried out using European-brewing technology methods.
Rhamnus prinoides L. Herit or Gesho in Amharic is a plant which grows up to 6m which cultivated in Ethiopia and is an important commodity which is sold in almost every traditional market place. It has a potential to serve as a raw material for Brewing Industries. In this work, the malt analysis, antioxidant activity of Gesho, Rhamnus prinoides and imported hops, effect of process variables in beer bitterness, physico-chemical analysis of finished beer and microbiological analysis of beer were done.
Bacteria almost disappeared at the end of the fermentation and pasteurization of the finished beer. Yeasts were dominated at the middle of phases. This phenomenon may be due to the synergic effect of Gesho antibacterial substance, alcohol concentration, reduction of pH (5.4 to 4.48) and antioxidant activity. Bitter taste value of 15.6Bu of Gesho being in the range of standard i.e.15-18Bu of hops was found to be comparable with the values of common varieties of hops. This should indicate that Gesho can serve as a substitute for hops used in the breweries.
Keywords: Antioxidant activity, Beer, Bitter taste, Herkule and Rhamnus prinoides.
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Keywords
Antioxidant activity; Beer; Bitter taste; Herkule and Rhamnus prinoides