Occurrence of the ribes odorant 3-sulfanyl-3-methylbutyl formate in aged beers

• Published in: Flavour and fragrance journal 2013-05, Vol.28 (3), p.174-179
• Main Authors: Tran, Thi Thu Hang, Nizet, Sabrina, Gros, Jacques, Collin, Sonia
• Format: Article
• Language: English
• Subjects: beer ageing; formate; polyfunctional thiols; ribes
• ISSN: 0882-5734; 1099-1026
• DOI: 10.1002/ffj.3152

ABSTRACT 2‐Sulfanyl‐3‐methylbutyl formate and acetate were synthesized without purification steps, quantified with a pulsed flame photometric equimolar detector, and characterized by comparison with commercially available 3‐sulfanyl‐3‐methylbutyl formate and acetate (retention indexes, mass spectra, odour descriptors, and intensities). Both formates exhibited a typical ribes flavour, in contrast to both acetates, which were much more piquant. The sensorial threshold of 3‐sulfanyl‐3‐methylbutyl formate was much lower (57 ng/l in beer, BE‐GC‐LoADS = 0.0006 ng) than those measured for the three other esters. Only 3‐sulfanyl‐3‐methylbutyl formate was perceived at the sniffing port in beer extracts. Concentrations up to 1230 ng/l were measured in pilot beers after 1 month at 20°C, although the compounds are rarely detected in commercial beers with highly oxygen‐protected bottling. Accelerated ageing in the presence of oxygen confirmed the key role of oxygen. Copyright © 2013 John Wiley & Sons, Ltd. 2‐Sulfanyl‐3‐methylbutyl formate and acetate were synthesized, and characterized by comparison with commercially available 3‐sulfanyl‐3‐methylbutyl formate and acetate (retention indexes, mass spectra, odour descriptors, and intensities). Only 3‐sulfanyl‐3‐methylbutyl formate was perceived at the sniffing port in beer extracts and concentrations up to 1230 ng/L were measured in pilot beers after one month at 20°C, although the compounds are rarely detected in commercial beers with highly oxygen‐protected bottling. Accelerated ageing in the presence of oxygen confirmed the key role of oxygen.