Effect of sucrose, trehalose and glutamate on the resistance to ethanol of frozen and freeze-dried acclimated oenological Lactobacillus plantarum strains

BÁRBARA MERCEDES BRAVO-FERRADA1; NATALIA BRIZUELA; ESTEBAN GERBINO; ANDREA GOMEZ-ZAVAGLIA; LILIANA SEMORILE; E. ELIZABETH TYMCZYSZYN

Ostrava

Congreso; CRYO 2015 - the 52nd Annual Meeting of the Society for Cryobiology; 2015

Lactobacillus plantarum is one of the species most widely used for malolacticfermentation in winemaking. Most of the strains are able to grow in the harshwine environment, producing different metabolites that improve the organolepticproperties of wine. For this reason, optimizing the preservation conditions ofoenological L. plantarum strains is essential in winemaking.The exposure of microorganisms to sub-lethal ethanol concentrationsprior wine inoculation (acclimation) is a usual step to improve bacterialviability. However, the effect of acclimation on bacterial preservation and ontheir technological properties has not been addressed hereto.The aim of this work was to investigate the effect of freezing andfreeze-drying on three strains of L. plantarum, previously acclimated in6 and 10% v/v ethanol. For each condition assayed, the protectant capacity ofthree agents (sucrose, trehalose and glutamate) was also evaluated.After freezing or freeze-drying, microorganisms were grown in syntheticwine containing 13 or 14% v/v ethanol and pH 3.5. Acclimation increased theresistance to ethanol after freezing and freeze-drying. In addition, sucrose, trehalose and glutamateshowed an adequate protective capacity as determined by plate counting andmultiparametric flow cytometry.The combination of acclimation treatment and protective agents appearsas a useful strategy to overcomethe detrimental effects of these preservation processes, with promissoryindustrial applications as dehydrated malolactic starters.