Petri dish method to select yeasts able to produce more pigmented table olives

Abstract

The study of pigment adsorption of yeasts used for table olive fermentation may allow the protection of olive colour, by excluding those strains adsorbing phenolic compounds responsible for the colour. Fifty-one table olive yeasts were grown on Petri dishes using two olive-based screening media - ‘olive pulp agar’ and ‘olive seed agar’; the red, green, and blue colour components of the yeast’s biomass were measured. Wide and significant differences among the yeasts were observed. Based on the statistical analysis, ten yeasts were selected, excluding all the strains exhibiting a too high pigment adsorption. The research proposes a simple analytical method to characterize yeasts for their pigment adsorption, thus allowing the enhancement of the table olive colour. The two media may be prepared using any olive cultivar, thus allowing a specific screening of the yeasts. The selection of those yeasts unable to adsorb olive pigments may allow the production of more pigmented table olives.