Fermentation Performance of Selected Microorganisms in Malbec Musts under Two Different Wine Making Conditions

Abstract

This work evaluates the fermentation performance of simultaneous cultures of selected indigenous Saccharomyces cerevisiae mc2, Kloeckera apiculata mF and Oenococcus oeni X2L in Malbec musts. Fermentations (3 l) were carried out at the pilot plant under two conditions: 1-initial pH 5.5, 60.24 mg/l SO2, 26°C) and 2-initial pH 3.8, 125 mg/l SO2, 28°C), using different culture combinations and S.cerevisiae IOC 18-2007 as control. The final wine densities were 0.992-0.997 g/l (10 days). Microorganisms grew in all conditions. Yeasts prevailed, especially S. cerevisiae (108 CFU/ml) while O. oeni reached 107 CFU/ml. Total reducing sugars consumption was >80% and full malate consumption was observed in all musts inoculated with O. oeni. Ethanol formation corresponded to Malbec variety (310-342 mM), while total acidity did not exceed organoleptic quality limit (4.6-6.49 g/l). Glycerol production was ~84.3-95.1 mM. Among tested esters, ethyl acetate/2-phenyl ethyl acetate showed highest concentration. The sensoryanalysis showed the highest scores for visual descriptors (fluency, color intensity and tonality), olfactory intensity, taste descriptors and general harmony. Thus, we propose an inoculation condition using a mixed yeasts-O.oeni culture and an optimal statistical point to improve microbial performance to obtain quality Malbec wines enhancing body and sensorial properties.