Selection of a new Saccharomyces yeast to enhance relevant sorghum beer aroma components, higher alcohols and esters. (October 2019) - Tokpohozin, Sedjro Emile
Abstract: The selection of Saccharomyces yeast which is able to produce high amounts of relevant aroma components from sorghum wort has been scarcely explored. Furthermore, generating sorghum beer with low levels of vicinal diketones (VDKs) is a permanent concern of brewers because of the wort's low amino acid content. To address these challenges, a performant Saccharomyces cerevisiae yeast was selected based on the higher alcohols and esters it synthesizes, and conditions influencing the young beer's VDK content were studied. Our results confirm that the low amino acid content limits aromagenesis by industrial ale yeast. By contrast, the selected yeast is able to efficiently produce higher alcohols and esters and is well adapted to tropical temperatures (27 °C). The young beer obtained from 13 °P sorghum wort using the isolated strain is characterized by a higher amount of aroma-active components such as isoamyl alcohol (116.25 ± 0.38 mg/L), isoamyl acetate (1.81 ± 0.02 mg/L) and ethyl acetate (22.07 ± 0.74 mg/L). The VDK content, however, is not only yeast strain dependent; it is strongly reduced by high fermentation temperature (27 °C) and increased wort gravity. Highlights: The low sorghum wort amino acid content limits aromagenesis by industrial ale yeast during fermentation. Yeast isolated from African beer starter exhibits high production of relevant aroma components. The isolated yeasts are well adapted to tropical temperatures (27 °C). Biotic and abiotic factors of brewing strongly influence the beer's VDKs content.