Increasing Dimethylsulfide and Polyfunctional Thiols, an Opportunity to Enhance the Fruity Flavors of NABLABs

Abstract

At present, non-alcoholic beers and low-alcoholic beers (NABLABs) suffer from premature oxidation when fresh, and from a lack of fruity fermentation aromas. In wines, dimethylsulfide (DMS) is known to enhance truffle nuances and the fruity character. This offers an opportunity to improve the flavor of NABLABs. In this work, levels of free DMS and its potential precursors (S-methylmethionine/SMM and dimethylsulfoxide/DMSO) were assessed in eleven commercial NABLABs, in parallel with their amounts of fruity esters and polyfunctional thiols. Except in two dry-hopped samples and a fruity beer, free DMS was detected at very low levels in all fresh NABLABs (four samples even displayed no detectable GC peak), likely because of dealcoholization or too-short fermentation. Through NABLABs aging, the free DMS concentration increased (+63% on average after two years), at a degree correlated with the initial SMM level (2–118 µg/L DMS eq.; R2 = 0.79). This SMM amount revealed to be also correlated with the group I amino acid residual content (more consumed through traditional fermentations). Unlike DMSO, SMM showed significant release of free DMS after aging in spiking experiments (4% degradation after 30 days at 20 °C). As fruity fermentation esters are found in NABLABs at much lower concentrations than in conventional lagers, increasing both DMS and polyfunctional thiols by dry hopping (or DMS-enriched extracts) emerges as an opportunity to improve them.