Malolactic fermentation induced by Lactobacillus plantarum in Malbec wines from Argentina

Abstract

The current market requirements to obtain wines with enhanced complexity and varietal character propose the finding of new microorganisms capable to dominate at an early stage of the vinification, to drive the malolactic fermentation (MLF) and to contribute to new and distinctive sensory profiles of the wines. During MLF malic acid naturally present in must is converted into lactic acid by a decarboxylation reaction driven by lactic acid bacteria, mainly Oenococcus oeni. Although inoculation with O. oeni is widely used, this microorganism presents some limitations. Recently, a new strain of Lactobacillus plantarum suitable for MLF in high pH wines has been selected. This study evaluates the capacity of L. plantarum V22 starter culture to complete MLF at laboratory and semi-industrial scale in Malbec musts from Argentina. Malbec musts were co-inoculated with S. cerevisiae D254 and L. plantarum V22 to conduct alcoholic fermentation and MLF respectively. In semi-industrial experiments sequential inoculation with O. oeni VP41 was performed, as the reference MLF procedure used in the industry, to allow a comparison for the efficiency of malic acid degradation. The alcoholic fermentation was not affected by the co-inoculation strategy. Malic acid was partially or totally consumed in spite of a gradual decrease in L. plantarum viability in all conditions assessed. This study demonstrated the feasibility to use L. plantarum as a starter culture to conduct MLF in Malbec musts, additionally suggesting that the successful completion of MLF may be associated with pH evolution during the fermentation process, rather than to initial must pH.