DisplayTitle

​​​​Yeast Nutrition and Metabolism: Effects on Beer Flavor

 

Graham G. Stewart (1) and R. Alex Speers (1,2). 1. International Centre for Brewing and Distilling, Heriot-Watt University, Riccarton, Edinburgh, Scotland, EH14 4AS. 2. The Canadian Institute for Fermentation Technology, Dalhousie University, Halifax, Nova Scotia, Canada

 

Abstract
The primary metabolites of wort fermentation are ethanol, carbon dioxide, and glycerol. They do not directly affect beer flavor, but they collectively influence beer character. Beer flavor is largely (but not exclusively) influenced by other wort fermentation products (also called secondary metabolites). Flavor products from wort fermentation have been progressively characterized during the past 50 years or so. These developments have been assisted by the genesis of novel analytical instrumentation and our enhanced knowledge of overall yeast metabolism (both nature and nurture influences) during wort fermentation. This paper attempts to correlate the progress of fermentation metabolism that will influence beer flavor. The major focus here is a review considering the control of the metabolic production of higher alcohols, esters, carbonyls, sulfur compounds, and phenolics that contribute to beer flavor. In addition, because of its importance as a current brewing process, the question of high-gravity wort fermentation and its influence on beer flavor is considered.

Keywords: beer flavor, carbonyls, carbon dioxide, esters, ethanol, fermentation, glycerol, higher alcohols, high-gravity brewing, phenols, sulfur compounds