MALOLACTIC FERMENTATION IN WINE BY DIRECT INOCULATION WITH FREEZE-DRIED LEUCONOSTOC-OENOS CULTURES

The identification of 850 bacterial isolates collected from French, Po rtuguese, Italian, and Spanish wines undergoing malolactic fermentatio n showed that 77% belonged to the species Leuconostoc oenos. Hybridiza tion of total bacterial DNA using phage DNA as probe indicated that 80 % of the L. oenos isolates were lysogenic. L. oenos strains were selec ted for growth in wine with low pH and high ethanol concentration by u se of a turbidostat and further screened for their ability to maintain the adaptation to the wine environment during propagation, freezing, and freeze-drying. Several of the selected freeze-dried strains surviv ed 100% the direct inoculation into commercial wines where they starte d to grow without a lag phase. The immediate survival and the lag phas e of the inoculated bacteria strongly influenced the total duration of the malolactic fermentation. Cultures for direct inoculation may subs tantially improve the management of malolactic fermentation in winemak ing.