The Effect of DL-Malic Acid on the Metabolism of L-Malic Acid during Wine Alcoholic Fermentation
Fabio Coloretti1, Carlo Zambonelli1*, Lorena Castellari2, Vincenzo Tini1 and Sandra Rainieri1,**
1Dipartimento di Protezione e Valorizzazione Agroalimentare (DIPROVAL), Università di Bologna, Villa Levi, Reggio Emilia, Italy
2Centro di Assistenza Tecnicologica in Enologia e Viticoltura, Tebano, Faenza, Italy
**Present address: Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 Japan
Article history:
Received June 10, 2002
Accepted November 7, 2002
Key words:
D-malic acid; DL-malic acid; L-malic acid; malo-alcoholic fermentation; yeast
Summary:
Insufficient wine acidity can affect wine quality and stability. To overcome this problem, DL-malic acid can be added to the grape juice prior to fermentation. We have investigated the effect of DL-malic acid on wine fermentations and its influence on the final concentration of L-malic acid, naturally present in grape juice. To this end yeast strains that metabolise L-malic acid in different ways were tested and compared; namely, Schizosaccharomyces pombe (efficient L-malic acid degrader), Saccharomyces cerevisiae (non-degrader), hybrid strain S. cerevisiae x S. uvarum (intermediate degrader) and Saccharomyces uvarum (promoting L-malic acid synthesis). In all cases, D-malic acid passively entered the yeast cells and did not undergo malo-alcoholic fermentation. However, its presence in the juice, as a component of the mixture of D- and L- malic acid (DL-malic acid), reduced the amount of L-malic acid that can be degraded or synthesised by yeasts during malo-alcoholic fermentation.
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