Malic acid distribution and degradation in grape must during skin contact : the influence of recombinant malo-ethanolic wine yeast strains
CITATION: Van Staden, J., et al . 2005. Malic acid distribution and degradation in grape must during skin contact : the influence of recombinant malo-ethanolic wine yeast strains. South African Journal of Enology & Viticulture, 26(1):16-20, doi:10.21548/26-1-2114.
The original publication is available at http://www.journals.ac.za/index.php/sajev
Wine acidity plays an important role in determining wine quality and ensuring physiochemical and microbiological stability. In high-acid wines, the L-malic acid concentration is usually reduced through bacterial malolactic fermentation, while acidulation in low-acidity wines is usually done during final blending of the wine before bottling. This study showed that skin contact did not influence the relative concentration of L-malic acid in the pulp and juice fractions from Colombard, Ruby Cabernet and Cabernet Sauvignon grape musts, with 32%-44% of the L-malic acid present in the pulp fraction. Four recombinant malo-ethanolic (ME) Saccharomyces wine yeast strains containing the malic enzyme (mae2) and malate transporter (mael) genes of Schizasaccharomyces pombe, effectively degraded the L-malic acid in both the juice and pulp fractions of all three cultivars, with a complete degradation of malic acid in the juice fraction within 2 days.