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

BÁRBARA MERCEDES BRAVO-FERRADA, NATALIA BRIZUELA, ESTEBAN GERBINO, ANDREA GÓMEZ ZAVAGLIA, LILIANA SEMORILE, E. ELIZABETH TYMCZYSZYN.

Ostrava

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

Society for Cryobiology

Lactobacillus plantarum is one of the species most widely used for malolactic fermentation in winemaking. Most of the strains are able to grow in the harsh wine environment, producing different metabolites that improve the organoleptic properties of wine. For this reason, optimizing the preservation conditions of oenological Lactobacillus plantarum strains is essential in winemaking. The exposure of microorganisms to sub-lethal ethanol concentrations prior wine inoculation (acclimation) is a usual step to improve bacterial viability. However, the effect of acclimation on bacterial preservation and on their technological properties has not been addressed hereto. The aim of this work was to investigate the effect of freezing and freeze-drying on three strains of L. plantarum, previously acclimated in 6 and 10% v/v ethanol. For each condition assayed, the protectant capacity of three agents (sucrose, trehalose and glutamate) was also evaluated. After freezing or freeze-drying, microorganisms were grown in synthetic wine containing 14 % v/v ethanol and pH 3.5. Acclimation increased the resistance to ethanol after freezing and freeze-drying. In addition, sucrose, trehalose and glutamate showed an adequate protective capacity as determined by plate counting and multiparametric flow cytometry. The combination of acclimation treatment and protective agents appears as a useful strategy to overcome the detrimental effects of these preservation processes, with promissory industrial applications as dehydrated malolactic starters.