Influence of malolactic bacteria inoculation scenarios on the efficiency of the vinification process and the quality of grape wine from the Central European region

The aim of this study was to evaluate the efficiency of malolactic fermentation in the production of red and white wine from high-acid musts (up to 9.5 g/L malic acid), typical for cool-climate European wine zones. Four vinification scenarios were investigated: alcoholic fermentation only, simultaneous malolactic and alcoholic fermentation, malolactic fermentation induced at the end of alcoholic fermentation, and spontaneous malolactic fermentation. Our results, confirmed in three independent wine seasons, indicate that the best results, expressed as the greatest dynamics and efficiency in the deacidification, were observed when alcoholic and malolactic fermentation was simultaneous (83.97–94.84% reduction in malic acid). A total reduction in malic acid in such acid musts was not possible. In the co-inoculation scenario, fermentation time was significantly reduced, there was no increase in volatile acidity, and the lowest residual sugar concentrations were noted. Advantageously, the timing of the malolactic bacteria inoculation had no effect on the metabolism of such secondary metabolites as citric and acetic acids as well as on the final ethanol and glycerol concentration. It was suggest that co-inoculation of yeast and bacteria can be a very useful technique in the process of cool-climate grape wine production and also can be regarded as being applicable on industrial scale specially for very high-acid grape must.