Utilization of the Dicarbonyl Compounds 3-Deoxyglucosone and 3-Deoxymaltosone during Beer Fermentation by <i>Saccharomyces</i> Yeasts

Abstract

In beer production, 1,2-dicarbonyl compounds such as 3-deoxyglucosone (3-DG) and 3-deoxymaltosone (3-DM) are formed via Maillard reaction or caramelization especially during malt kilning or wort boiling, resulting in substantial concentrations in wort. Consequences of dicarbonyl compounds for yeast metabolism are widely unknown. In the present study, the handling of 3-DG and 3-DM by Saccharomyces strains from different habitats in wort and during beer fermentation was investigated. We show that beer yeast strains induced a faster 3-DG degradation in Pilsner wort and were additionally more stress-resistant to 3-DG compared to yeasts isolated from natural habitats. In fermentation experiments comparing a light wort and a dark wort prepared from malt extracts, it could be shown that high levels of 3-DM in dark wort influence the utilization of 3-DG by yeasts, and thus higher levels of 3-DG remain in the wort. Beer yeast strains showed an increased formation of 3-deoxyfructose (3-DF) with up to 220 µM, which is possibly due to a preferred metabolization of 3-DM, as indicated by the low degradation rate of 3-DG. In contrast, yeasts isolated from natural habitats produced significantly lower amounts of 3-DF. This suggests an adaptation of technologically used yeasts to metabolization of dicarbonyl compounds, possibly as a result of beer yeast domestication.

Keywords

• Maillard reaction
• 3-deoxyglucosone
• 3-deoxymaltosone
• beer wort
• <i>Saccharomyces</i> yeasts
• metabolization