Abstract
Foodstuffs, including beverages like beer and wine, often undergo chemical changes during storage that alter their sensory properties. In the brewing process, fermentable sugars are converted by yeast into ethanol and carbon dioxide, along with by-products such as higher acyclic and aromatic alcohols, multivalent alcohols, esters, carbonyl compounds, organic acids, and sulphur-containing compounds, all of which affect the flavour of the beer. Beer's chemical composition is unquestionably determined by the nature of the raw materials and the production process.
This study investigated the impact of commercial glutathione (GSH) enriched winemaking Inactive Dry Yeast (G-IDY) preparations on preserving beer's sensory properties during storage. While these preparations have been effective in preserving wine, the study found no significant impact of G-IDY preparations on yeast fermentation activity or beer storage. In fact, a higher G-IDY dosage (0.8 g/L) negatively affected fermentation, resulting in an apparent attenuation of 56% as compared to approximately 80% for the control sample and the sample with the recommended G-IDY dosage. Although there was a slight positive effect on colour preservation at non-optimal storage temperatures (40°C for 5 days) and a minor reduction in bitterness decline (2% for the G-IDY recommended dosage sample vs. 23% and 25% for the sample with the highest G-IDY dosage and control sample, respectively), G-IDY generated unpleasant sulphurous off-flavours and increased beer haze (35 FTU compared to 95 FTU for the control sample and the sample with the recommended G-IDY dosage, respectively). G-IDY was ultimately found to be ineffective and inappropriate for maintaining beer's overall sensory properties during storage.