Co-fermentation of non- yeasts with FST 1.7 for the production of non-alcoholic beer.

The non-alcoholic beer (NAB) sector has experienced steady growth in recent years, with breweries continuously seeking new ways to fulfil consumer demands. NAB can be produced by limited fermentation of non- yeasts; however, beer produced in this manner is often critiqued for its sweet taste and wort-like off-flavours due to high levels of residual sugars and lack of flavour metabolites. The use of in limited co-fermentation with non- yeasts is a novel approach to produce NABs with varying flavour and aroma characteristics. In this study, lab-scale fermentations of KBI 12.1 and C6.1 with FST 1.7 were performed and compared to a brewer's yeast, WLP001. Fermentations were monitored for pH, TTA, extract reduction, alcohol production, and microbial cell count. The final beers were analysed for sugar and organic acid concentration, free amino nitrogen content (FAN), glycerol, and levels of volatile metabolites. The inability of the non- yeasts to utilise maltotriose as an energy source resulted in extended fermentation times compared to WLP001. Co-fermentation of yeasts with lactic acid bacteria (LAB) resulted in a decreased pH, higher TTA and increased levels of lactic acid in the final beers. The overall acceptability of the NABs produced by co-fermentation was higher than or similar to that of the beers fermented with the yeasts alone, indicating that LAB fermentation did not negatively impact the sensory attributes of the beer. C6.1 and FST 1.7 NAB was characterised as fruity tasting with the significantly higher ester concentrations masking the wort-like flavours resulting from limited fermentation. NAB produced with KBI12.1 and FST1.7 had decreased levels of the undesirable volatile compound diacetyl and was described as 'fruity' and 'acidic', with the increased sourness masking the sweet, wort-like characteristics of the NAB. Moreover, this NAB was ranked as the most highly acceptable in the sensory evaluation. In conclusion, the limited co-fermentation of non- yeasts with LAB is a promising strategy for the production of NAB.