The impact of beer-spoiling yeast on flavour development in non-alcoholic beers.

No- and low-alcohol beverages reflect a commercially important and rapidly expanding market. These products represent a unique environment that differs nutritionally and environmentally from standard product types and are generally regarded as being at higher risk of spoilage. Beer-spoiling yeasts represent a particular risk within the brewing chain, typically impacting the sensorial properties of the final beverage. However, little is known about their effects in no- and low-alcohol products. This study aimed to determine the impacts of beer-spoiling yeasts on the flavour profiles of non-alcoholic beer. A total of 30 beer-spoiling yeast strains were analysed for their spoilage properties. Atmospheric-pressure chemical ionisation-mass spectrometry (APCI-MS) was employed to identify strains with the greatest impact on volatile flavour profiles. From this initial screening, 14 strains representing key beer-spoiling yeast species were selected, including Brettanomyces, Candida, Debaryomyces, Hanseniaspora, Kazachstania, Kluyveromyces, Pichia, Saccharomyces, Torulaspora, Wickerhamiella, Cyberlindnera and Zygosaccharomyces. The capacity of these yeast to impact concentrations of expected beer fermentation volatiles (targeted analysis) and produce atypical volatile compounds (non-targeted analysis) was assessed via head space-gas chromatography coupled with flame ionising detection (HS-GC-FID), and gas chromatography mass spectrometry (GC-MS), respectively. The data provides insight into the relative spoilage potential of beer-spoiling yeasts in relation to standard beer styles, indicating that the negative effects of contamination are exacerbated in non-alcoholic beer. Importantly, elevated alcohol production was also observed, with both commercial and legislative implications. This data is directly relevant for the global brewing industry, and other related sectors where the demand for no- and low-alcohol alternatives is prevalent.