Modulation of the Sulfanylalkyl Acetate/Alcohol Ratio and Free Thiol Release from Cysteinylated and/or Glutathionylated Sulfanylalkyl Alcohols in Beer under Different Fermentation Conditions.

The occurrence of a substantial pool of cysteinylated and glutathionylated forms of polyfunctional thiols has been evidenced for several dual-purpose hop varieties, and so is the ability of yeast to release free thiols from these forms through fermentation. The present work aimed to investigate the effect of temperature, wort density, maturation time, and strain on the efficiency of free thiol release by yeasts. Model media at 12, 15, or 17°P were spiked with three cysteinylated (Cys-) or three glutathionylated (G-) sulfanylalkyl alcohols (Cys- or G-3-sulfanylpentan-1-ol, 3-sulfanyl-4-methylpentan-1-ol, and 3-sulfanylhexan-1-ol), fermented for 7 days at 18, 24, and 28 °C, and kept at 4 °C for varying number of days.