Odorant polyfunctional thiols issued from bottle beer fermentation
(2011) XII Weurman flavour research symposium — Location: Zaragoza, Espagne (27.September.2011)
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- Bottle refermentation which imparts beer effervescence and resistance against infection and oxidation is also known to improve flavor profile and stability. By this process, some stale off-flavors exhaled by aldehydes (trans-2-nonenal, 3-methylthiopropionaldehyde, 3- methylbutanal ..) are reduced into alcohols (1, 2). Unfortunately, yeast esterases can also strongly affect the beer fruity character by hydrolyzing isoamyl acetate, ethyl hexanoate and ethyl octanoate (1, 2). Thiols are known to have a strong impact on the overall aroma of fermented beverages (3). More than ten polyfunctional thiols were detected in fresh lager beers (4). The thiols profile of refermented beer has been little studied. In this work, the polyfunctional thiol contents of commercial and pilot beers submitted or not to bottle refermentation were compared. A strong organoleptic impact of the bottle refermentation process was evidenced in all samples by a training panel (70%). A specific pHMB thiols extraction (5) was applied and the extracts analyzed by GC-MS, GC-PFPD and GColfactometry (AEDA). A large number of sulfanylalcools, sulfanylacetates and sulfanylcarbonyles revealed produced during the refermentation process, especially after three weeks. Among them, 3-sulfanylpropanol reached a FD olfactometric values up to 32768. According to their beta-sulfanyl structures, hop cystein adducts are suspected to be hydrolyzed by refermentation yeast-derived lyases. Therefore, a better control of the refermentation process requires both an excellent control of yeast vitality and a strict selection of the hop varieties.
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Nizet, S., Gros, J., & Collin, S. (2011). Odorant polyfunctional thiols issued from bottle beer fermentation. XII Weurman flavour research symposium, Zaragoza, Espagne. https://hdl.handle.net/2078.5/158732