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J Mass Spectrom

Title:		Online monitoring of higher alcohols and esters throughout beer fermentation by commercial Saccharomyces cerevisiae and Saccharomyces pastorianus yeast
Author(s):		Roberts R; Khomenko I; Eyres GT; Bremer P; Silcock P; Betta E; Biasioli F;
Address:		"Department of Food Science, University of Otago, Dunedin, New Zealand. Sensory Quality Unit, Research and Innovation Centre, Fondazione Edmund Mach, Trento, Italy"
Journal Title:		J Mass Spectrom
Year:		2023
Volume:		20230725
Issue:
Page Number:		e4959 -
DOI:		10.1002/jms.4959
ISSN/ISBN:		1096-9888 (Electronic) 1076-5174 (Linking)
Abstract:		"Higher alcohols and esters are among the predominant classes of volatile organic compounds (VOCs) that influence the quality of beer. The concentrations of these compounds are determined through a specific yeast strain selection and fermentation conditions. The effect of yeast strains on the formation of higher alcohols and esters throughout fermentations (at 20 degrees C) was investigated. Flavour-relevant esters (ethyl acetate, isoamyl acetate, ethyl hexanoate and ethyl octanoate) and higher alcohols (isoamyl alcohol, isobutyl alcohol and phenylethyl alcohol) were monitored throughout the fermentation using proton transfer reaction-time of flight-mass spectrometry (PTR-ToF-MS) coupled with an automated sampling system for continuous measurements. Compound identification was confirmed by analysis of samples using gas chromatography-mass spectrometry (GC-MS). Results demonstrated the specific time points where variation in higher alcohol and ester generation between yeast strains occurred. In particular, the concentrations of isoamyl acetate, ethyl octanoate and isoamyl alcohol between yeast strains were significantly different over the first 2 days of fermentation; whereas, after Day 3, no significant differences were observed. The two Saccharomyces pastorianus strains produced comparable concentrations of the key higher alcohols and esters. However, the key higher alcohol and ester concentrations varied greatly between the two S. cerevisiae strains. The use of PTR-ToF-MS to rapidly measure multiple yeast strains provides new insights on fermentation for brewers to modify the sensory profile and optimise quality"
Keywords:		brewing higher alcohols and esters proton transfer reaction-time of flight-mass spectrometry yeast;
Notes:		"PublisherRoberts, Rebecca Khomenko, Iuliia Eyres, Graham T Bremer, Phil Silcock, Patrick Betta, Emanuela Biasioli, Franco eng University of Otago/ Fondazione Edmund Mach/ England 2023/07/26 J Mass Spectrom. 2023 Jul 25:e4959. doi: 10.1002/jms.4959"