Influence of FLO1 and FLO5 genes on aroma profile of sparkling wines

This study investigated the influence of S. cerevisiae F6789A strain and its derivative mutants – harbouring FLO1 gene deletion (F6789A-ΔFLO1) and FLO5 gene deletion (F6789A-ΔFLO5) – on secondary fermentation, autolysis outcome and aroma compounds production. Data revealed differences in terms of metabolic behaviour leading to the production of sparkling wines with different characteristics. F6789A showed the best fermentation kinetic reaching a pressure of 5 bar inside the bottle, while F6789A-ΔFLO1 and F6789A-ΔFLO5 reached 4 bar and 3.8 bar, respectively. Cell viability was in agreement with fermentation kinetics. In fact, F6789A showed the highest number of cells. An early autolysis was observed for F6789A-ΔFLO5. Differences were observed especially for esters in terms of number and quantity of esters released. In particular, the parental strains produced 39 different esters while F6789A-ΔFLO1 and F6789A-ΔFLO5 27 and 35, respectively. F6789A-ΔFLO5 was the main ester producer with a total amount of about 89 mg/L. Sensory analysis showed that all the strains produced balanced sparkling wines with negative and positive attributes arranged in good proportions, showing good aroma descriptors. Obtained data suggested that FLO1 or FLO5 genes had a pleiotropic effect affecting not only flocculation ability but also other metabolic traits.