Selecting a Zygosaccharomyces rouxii strain with high potential for concentrate grape juice spoilage

ROJO M.C; STURM M.E; MERCADO L.; TORRES A.; COMBINA M.

Puerto Madryn

Congreso; XLVI Reunión Anual de la SAIB; 2010

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Argentinas grape production is mainly devoted to the industry, where wine and grape juice concentrate are the two major types of commercial products. Because of its high sugar concentrations and low pH, juice concentrates are more stable than other juice products, and therefore they only support the development of a reduced number of microorganisms. Previous works have identified Zygosaccharomyces rouxii as the main spoilage yeast present in concentrate musts of Argentina. Nevertheless, using different strains of this same species, we have found a significant variation of the growth behaviour according to the strain analyzed. The aim of this work was to select a native strain of Z. rouxii that presents the proper growth parameters, in order to be used for future tests of concentrate grape must self life estimation. Three strains of Z. rouxii were evaluated in 68 Brix concentrate grape must. The yeast population was monitored by viable count and turbidity and growth parameters were estimated by the Baranyi model. We found differences for the three assayed strains with respect to the growth rate, lag phase as well as the starting point of the must spoilage (7, 11 and 15 days). Finally, the strain MC9 showed the proper growth parameters (absence of lag phase, and the fastest growth rate) and was therefore selected for the future assays of concentrate grape must self life estimation.