Dionysios Koulougliotis, Nikolaos Kopsahelis, Chrysanthi Pateraki, Iliada Lappa, Dimitra Alimpoumpa, Vasiliki Diamanti, Alexandros Laggis, Adamantia Kampioti and Effimia Eriotou
The chemical composition of wine is affected by many factors among which grape microbial ecology and the fermentation process.Very few wineries of Lefkada island employ spontaneous fermentation, using wild yeasts found on the grapes, to ensure “local and distinguished bouquet ” in their wines. Our aim was to explore the indigenous yeast microbiota of the local red grape variety Vertzami, select indigenous Saccharomyces cerevisiae strains and determine the antioxidant activity of the produced wine.In total, 231 yeast strains were isolated from wine lees at the end of spontaneous fermentation and identified via the API 20C AUX system.Alcohol resistance was determined by growing cells onto YEPD plates at 0-17%v/v ethanol. Sulfite tolerance was examined by growing strains in YEPD broth containing 100 mg/L SO2. Thirty yeast isolates were selected and used in small scale vinifications. The antioxidant activity of each wine product was determined spectrophotometrically (DPPH absorbance at 517 nm).The yeast species identified included S. cerevisiae (75.7%), Candida lusitiniae (11.3%) and Candida famata (9.1%) (3.9% not identified). 78.8% of the yeast strains tolerated 12% ethanol whereas only 22.1% grew at 17%. All S. cerevisiae strains were sulfite-resistant whereas all other yeasts were sulfite-intolerant. The thirty wine samples exhibited a mean antioxidant activity of 1.38 mmol Trolox/l. Statistical analysis provided evidence for two distinct clusters A (11 samples) and B (19 samples) with different mean antioxidant activities (1.53 and 1.28 mmol Trolox/l, respectively).The authors acknowledge support from the Operational Programme “Ionian Islands 2014-2020” (Project: MIS 5006342)
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