In vitro potential antioxidant activity of indigenous yeasts isolated from virgin olive oil

AIM: The aim of the present study was to investigate the in vitro antioxidant activity of yeast strains isolated from virgin olive oil. METHODS AND RESULTS: The 2,2-diphenyl-1-picryl-hydrazyl (DPPH) free-radical scavenging activity of single cultures of 24 yeast strains belonging to eight species isolated from virgin olive oil was evaluated and compared with that of the reference yeast Saccharomyces boulardii. All the yeasts studied in vitro showed antioxidant activity similar to or superior to that of the reference yeast. The highest antioxidant activity was observed in Nakazawaea wickerhamii, which exceeded the value reached by the reference strain S. boulardii, while the significantly lowest values were observed in the Candida adriatica, Candida diddensiae and Barnettozyma californica strains. Tests performed with virgin olive oil enriched with Wickerhamomyces anomalus and S. boulardii yeast biomasses showed a positive correlation between the microbial biomass used and the percentage of antioxidant activity observed during 60 days of storage. Survival in virgin olive oil was also significantly higher for W. anomalus compared to S. boulardii. CONCLUSIONS: All the oil-borne yeasts studied showed DPPH free-radical scavenging activity in both aqueous and oily media. SIGNIFICANCE AND IMPACT OF THE STUDY: For the first time, the antioxidant activity of the microbiota of virgin olive oil is reported. This activity may indicate the probiotic characteristics of the microbiota.