Exploitation of Three Non-Conventional Yeast Species in the Brewing Process

Consumers require high-quality beers with specific enhanced flavor profiles and non-conventional yeasts could represent a large source of bioflavoring diversity to obtain new beer styles. In this work, we investigated the use of three different non-conventional yeasts belonging to , , and species in pure and mixed fermentation with the commercial starter US-05. All three non-conventional yeasts were competitive in co-cultures with the , and they dominated fermentations with 1:20 ratio ( /non-conventional yeasts ratios). Pure non-conventional yeasts and co-cultures affected significantly the beer aroma. A general reduction in acetaldehyde content in all mixed fermentations was found. and in mixed and in pure cultures increased higher alcohols. led to a large reduction in pH value, producing, in pure culture, a large amount of lactic acid (1.83 g/L) while showing an enhancement of ethyl butyrate and ethyl acetate in all pure and mixed fermentations. decreased the main aroma compounds in comparison with the but showed a significant increase in ethyl butyrate and ethyl acetate. Beers produced with were characterized by an increase in the isoamyl acetate and α-terpineol content.