Evaluarea efectului de inactivare prin tratament PEF a germenilor de alterare a vinurilor

Abstract

The treatment in Pulsed Electric Field (PEF) represents an application of PEF technology to feeding liquids in order to render them sterile. The present study was initiated due to the fact that this treatment is of utmost importance for the enological area. The objective which was followed consisted in evaluating the inactivation effects produced by PEF treatment applied to the germs responsible for wine damaging. Two experiments were carried out, one of them being under specialized control, the other one concerning the natural development of the germs in wines. The variable factor of the controlled experiment was represented by the type of germs (yeast strains and, respectively stems of bacteria), and in case of the natural experiment, the level of wine stability. The studied germs were Saccharomyces fermentati, Leuconostoc oenos (P+) 149, Leuconostoc oenos (X+), Lactobacillus plantarum 36, Acetobacter vini VR1 and Acetobacter vini VA1. The level of wine stability was of 5, 4 and 3 in case of the wines taken into study. The results obtained emphasized the fact that PEF treatment significantly influences the viability of the germs responsible for wine damaging, their sensitivity being however specific to the group and species of microorganisms. The strongest bactericide effect was registered in case of the lactic bacteria belonging to Leuconostoc oenos (P+) species to which the diminution rate was of 3.45. Saccharomyces fermentati had the diminuation rate value of 2.95. Leuconostoc oenos (X+) and Lactobacillus plantarum 36 revealed an average resistance to PEF treatment, their diminution rate registering 2.47. The acetic bacteria proved to be the most resistant, maybe because of the tiny dimensions of their cells. The PEF treatment applied to the wines contaminated by damaging germs significantly diminished their microbial load. The germ diminution rate oscillated according to the nature of the contaminating agent and to the 19 Universitatea de Ştiinţe Agricole şi Medicină Veterinară Iaşi treatment length of time. Between the level of wine stability and the diminuation rate of the microorganisms, a direct relationship of 1st grade was registered. The study which was carried out proved that the PEF treatment represents a real potential for accomplishing wine sterilization.