The effects of freezing and freeze-drying of Oenococcus oeni upon induction of malolactic fermentation in red wine

Abstract The use of Oenococcus oeni starter cultures for the induction of malolactic fermentation (MLF) in wine permits control over the timing of the process and the quality of the wine. Successful inoculation of bacterial starter cultures into wine depends on the selection of suitable strains and on the preparation and conservation of those cultures. Medium for Leuconostoc oenos (MLO) is the best medium for easy and rapid growth of O. oeni cultures under laboratory controlled conditions for isolation and identification. However, this study showed that O. oeni cells inoculated in MLO failed to induce MLF in wine while cells grown in Medium of Preculture (MP) or wine, stored at −20 °C or freeze-dried retained the ability to induce MLF when inoculated in wine. Our results suggest that the use of freeze-dried cultures of O. oeni previously grown in MP is the best choice for industrial application.