A fast and simple method for wild yeast flora detection in winemaking

Francesca Comitini, Mariza Stringini, Manuela Taccari, Maurizio Ciani

Dipartimento S.A.I.F.E.T. sez. di Microbiologia Alimentare, Industriale e Ambientale, Università Politecnica delle Marche, Ancona, Italy

Abstract: An easy technique for a fast determination of wild yeast population-colonizing grape must before fermentation is described. The mathematical relationship between viable cell number and oxygen consumption rate was determined using a simple pO₂ electrode chamber. This relation was determined in pure cultures belonging to six yeast species related to wine environment and in natural samples of grape must collected at the time of the grape delivery in the wineries. Results indicated a significant relationship between oxygen consumption rate and viable cell count of the wine yeast species tested. The evaluation of natural grape must samples indicated that the presence at pre-fermentative of wide contaminant yeast flora at a level commonly believed responsible for uncontrolled microbiological process in winemaking (>10⁶ CFU ml⁻¹), was easily detected. Since the results are available in a short time, this method could be profitable used to detect the presence of contaminant level of wild yeasts reducing the risk of uncontrolled start fermentation that could compromise the quality of final product.

Keywords: wild yeasts contamination, oxygen consumption, O₂ probe