Influence of a malolactic starter on the quality of the cider produced on an industrial scale

The application of starter culture technologies to induce the malolactic fermentation in cidermaking are not yet established, as is already the case in winemaking. In this work, a selected indigenous cider malolactic strain was tested as a starter culture to assess its implementation and its influence on cider production on an industrial scale (10,000 l). The results showed that the culture, under the fermentation conditions tested, allowed successful achievement of the malolactic fermentation. Analysis of L-malic acid in the fermenting apple must medium revealed a highly significant difference in the rate of consumption of this acid from the moment of bacterial inoculation when compared with that of the control. The concentration of the malolactic starter culture maintained the inoculation level (106 cfu/ml) during the process, the level necessary to ensure the malolactic fermentation. Thus, the cider malolactic starter culture showed good adaptation to the harsh environmental conditions found in the fermenting apple must, such as low temperature and the presence of SO2 and ethanol. Several parameters were monitored during the process (specific gravity, temperature, pH, free SO2 content, microbiological count, malic acid degradation rate, lactic acid formation, other major organic acids and volatile compounds) under inoculated and not inoculated conditions.