Volatile organic metabolite profiling of a broad collection shows the brewing potential of non-conventional yeast

Modern brewing requires new yeast starters to meet consumer flavour preferences. The organoleptic characteristics of beer are the result of a complex mixture of numerous compounds, mostly volatile organic metabolites (VOMs) derived from yeast fermentation. In this study, the profile of VOMs produced by 184 yeast strains under ale brewing conditions was analysed. Yeasts of the genus Saccharomyces (S. cerevisiae, S. kudriavzevii, S. uvarum, S. eubayanus, S. paradoxus, S. mikatae, S. jurei, and S. arboricola), Saccharomyces hybrids (S. pastorianus, as commercial control, S. cerevisiae x S. kudriavzevii, S. cerevisiae x S. uvarum and S. eubayanus x S. uvarum) and non-Saccharomyces yeasts (Kazachstania, Naumovozyma and Nakaseomyces spp) were studied. Gas chromatography coupled to mass spectrometry (GC-MS) has been used to analyse 62 extracellular volatile compounds. The k-means cluster analysis classified the yeasts into four different clusters and curiously found that: Almost all of the Saccharomyces hybrids studied, regardless of their parental species or source of isolation, exhibit a metabolic profile similar to that of S. pastorianus and strains isolated from beer. This suggests that they exhibit similar metabolic behaviour and have an interesting profile for industrial use. In addition, specific strains of S. cerevisiae, S. uvarum and S. paradoxus have been found to produce valuable compounds for the brewing industry.