CONICET | Buscador de Institutos y Recursos Humanos

The aim of this work was to study the protective effect of sucrose, trehalose and glutamate duringfreezing and freeze-drying of three oenological Lactobacillus plantarum strains previously acclimated inthe presence of ethanol. The efficiency of protective agents was assessed by analyses of membraneintegrity and bacterial cultivability in a synthetic wine after the preservation processes. No significantdifferences in the cultivability, with respect to the controls cells, were observed after freezing at 80 Cand 20 C, and pre-acclimated cells were more resistant to freeze-drying than non-acclimated ones.The results of multiparametric flow cytometry showed a significant level of membrane damage afterfreeze-drying in two of the three strains. The cultivability was determined after incubation in wine-likemedium containing 13 or 14% v/v ethanol at 21 C for 24 h and the results were interpreted usingprincipal component analysis (PCA). Acclimation was the most important factor for preservation,increasing the bacterial resistance to ethanol after freezing and freeze-drying. Freeze-drying was themost drastic method of preservation, followed by freezing at 20 C. The increase of ethanol concentrationfrom 6 to 10% v/v in the acclimation medium improved the recovery of two of the three strains. Inturn, the increase of ethanol content in the synthetic wine led to a dramatic decrease of viable cells in thethree strains investigated. The results of this study indicate that a successful inoculation of dehydratedL. plantarum in wine depends not only on the use of protective agents, but also on the cell acclimationprocess prior to preservation, and on the ethanol content of wine.