The composition of the endogenous yeast population present in grapes and must solids of Mavrodafni Kefalonias was studied and the alcohol tolerance of each strain was determined. The most frequently encountered species on the grapes were Rhodotorula glutinis, Candida lusitiniae, Cryptococcus laurentii, Candida famata and Kloeckera species with frequencies 28.6%, 19%, 13.9%, 12.6% and 9.1% respectively. Saccharomyces cerevisiae was the sole species detected in must solids. The most alcohol

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... nt non-Saccharomyces yeast species found were Candida guilliermodii and Kloeckera species with some strains (3 and 16 respectively) tolerating up to 10% v/v ethyl alcohol. S. cerevisiae strains were found to tolerate up to 17% v/v alcohol. Mavrodafni Kefalonias red wine was produced in small scale vinifications from fifteen highly alcohol tolerant strains. The antioxidant activity of the must material and the fifteen wine samples was determined via measurement of their ability to scavenge the DPPH (2,2diphenyl-1-picrylhydrazyl) radical. All wine samples showed similar radical scavenging capacity with an average value of (6.9 ± 0.3) mmol Trolox/L while the must material showed increased antioxidant activity by ca 60%. To our knowledge, this is the first report on the endogenous yeast flora of the Mavrodafni Kefalonias grape variety and the antioxidant activity of the corresponding red wine and must.