Maria Gilda Stivala, Margarita Beatriz Villecco, and Pedro Aredes Fernandez*
*Universidad Nacional de Tucuman, Ayacucho 471, 4000, Argentina 
(pedro.aredes@fbqf.unt.edu.ar)

During winemaking, the presence of lactic acid bacteria (LAB), principally Lactobacillus genera, can cause wine deterioration. This work examined the effect of wine low molecular weight (LMF) phenolic fraction on the viability of enological LABs. The LMF were extracted from a young (Y) and aged (A) Tannat wine varietal produced in the same wine cellar located at Tucumán, Argentina. LMF was obtained by successive extractions with ethyl acetate. The phenolic compound (PC) content of the LMF extract was characterized qualitatively and quantitatively by LC-DAD-FLD. Three strains of L. hilgardii (5w, 6F, and X1B) and two strains of Oenococcus oeni (m and VP41) were cultured in synthetic wine-like medium (SWM), pH 4.5, supplemented with LMF-Y and LMF-A at identical concentration as present in wine. In the LMFs, 20 PCs were identified and quantified. The total concentration of PCs was greater in LMF-Y (95.1 mg/L) than in LMF-A (61.4 mg/L). After 72 hrs incubation, all LAB studied increased the viable cell concentration in SWM (control), except for O. oeni m, which maintained its viability. In the presence of LMF-Y, L. hilgardii 5w and 6F stopped growing with respect to control medium, and L. hilgardii X1B, O. oeni m, and VP41 decreases their viability by 0.17, 0.34, and 0.12 log cfu/mL, respectively. The addition of LMF-A to SWM decreased microbial viability in all strains studied, but O. oeni VP41 was the most sensitive strain, with a strong decrease in cell concentration of 3.06 log cfu/mL. These results constitute an important contribution to elucidate, at least in part, the effects of wine aging on LMF composition and their influence on viability of enological LABs. In addition, a quali-quantitative characterization of PC composition was performed for the first time in Tucuman wines.

Funding Support: CONICET