Study of a Sorghum Malt Wort Supplemented with Vernonia amygdalina Extract, a Substitute Hop Compound for Bitterness

Abstract

Malted sorghum wort, supplemented with Vernonia amygdalina extract during boiling, was fermented with a Saccharomyces strain for 192 h. This was a preliminary study to examine how use of this substitute hop compound affected alcohol production and yeast growth. Alcohol content was modelled as a 3-parameters Gompertz growth model. The three levels of extract of Vernonia amygdalina, which were added to sorghum malt wort, induced reductions in alcohol content of 3, 12, and 25% after 192 h of fermentation and reductions in optical density at 600 nm of 27, 33, and 48%, respectively, were obtained. Yeast growth curve peaked at around 60 h and alcohol decreased as the content of Vernonia amygdalina extract increased.