The diversity of the indigenous yeast strains present in the product of spontaneous vinification (5-day fermentation period) of the red grape variety Avgoustiatis Zakynthou (Ionian Islands, Greece) was explored, followed by determination of the alcohol tolerance of all identified strains. The non-Saccharomyces yeast species found were Kloeckera sp., Rhodotorula glutinis, Candida famata and Candida lusitaniae with frequencies 29%, 16.2%, 15.7%, and 9.1% respectively. In addition, the yeast species Saccharomyces cerevisiae 1 and 2 were encountered with the same frequency equal to 14.8%. Candida famata, Candida lusitaniae and Kloeckera sp. were the non-Saccharomyces yeast species which exhibited the highest endurance in alcohol, with some of their strains reaching tolerances up to 10% v/v. The large majority of the Saccharomyces cerevisiae strains were shown to tolerate up to 17% v/v alcohol. A total of thirty Saccharomyces cerevisiae strains were selected and employed for the production of an equal number of Avgoustiatis Zakynthou wines via small scale vinifications. Subsequently, the antioxidant activity of all wine samples was determined via measurement of their capacity to scavenge the DPPH (2, 2-diphenyl-1-picrylhydrazyl) free radical. The antioxidant activity of the 30 wine samples had a mean value of (0.81 ± 0.09) mmol Trolox/L (Min: 0.64 – Max: 0.95). Statistical analysis provided evidence for a weak dependence of the observed antioxidant activity on the yeast strain employed during fermentation. To our knowledge, this is the first study on the indigenous yeast diversity associated with the red grape variety Avgoustiatis, which grows on the island of Zakynthos (Ionian Islands, Greece), and of the antioxidant activity of the produced wine.

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