Evolution of yeast biodiversity and volatile compounds during spontaneous fermentation of ‘Karasakiz’ grapes from different regions over two consecutive vintages

Spontaneous fermentation may produce complex and unique wines with geographical designations due to the region-specific yeast flora and variations in must characteristics. The current study focused on the yeast diversity and changes in volatile compounds during the spontaneous fermentation of ‘Karasakız’ grapes from three sub-regions of Çanakkale province, Turkey for two vintages (2019 and 2020). This is the first study on the diversity of autochthonous yeasts during wine fermentation of ‘Karasakız’ variety. In the present work, the strains belong to Hanseniaspora uvarum, Starmerella bacillaris, Pichia terricola, Metschnikowia pulcherrima and Zygoascus hellenicus by PCR-RFLP of the ITS region were identified . A total of 272 isolates were identified as S. cerevisiae. Yeast population and diversity changed related to the sub-region and the vintages. However, H. uvarum and S. bacillaris were common denominators of three regions evaluated. H. uvarum was dominant in the early stages of the fermentation, except for Bozcaada 2019 vintage. Bozcaada region also exhibited higher S. cerevisiae strain diversity compared to other regions. 1-Hexanol and 1-octanol gradually decreased during the fermentation of ‘Karasakız’ grapes, while the concentration of isoamyl alcohol, phenylethyl alcohol and ester compounds increased by the fermentation but with some fluctuation.