Impact of Grape Temperature at Pressing on Organic Acids and Oenological Characteristics of Méthode Cap Classique Wines
B.S. Chidi1*, M. Mafata2, N.Z. Notshokovu1, F. van Jaarsveld1
Maintaining the chemical composition of a wine is essential for the wine industry. Although the sugar-acid balance of a wine is of primary sensory importance, individual acids and oenological variables are equally important. The main focus of this study was to investigate the impact of grape temperature at harvest on the volatile acidity (VA), titratable acidity (TA), pH and alcohol levels, and the organic acid (citric, malic, pyruvic and succinic) characteristics of Méthode Cap Classique (MCC) wines produced from grape cultivars obtained from two regions in South Africa. Chardonnay and Pinot noir grapes were obtained from the Robertson (warm) and Elgin (cool) regions and were subjected to different temperature treatments, viz. 0°C, 10°C, 25°C and 30°C, before further processing, including pressing, primary fermentation, blending, tirage, secondary fermentation, riddling and disgorging. The grape temperature was mostly responsible for the higher pH of the Robertson (0°C and 10°C) and lower pH (0°C) of the Elgin post-tirage wines. Chardonnay-base wines from both regions that were vinified from grapes at lower temperatures (0°C and 10°C) were richer in malic and succinic acid, while Pinot noir wines from both regions were characterised by higher malic, citric and pyruvic acid. Pyruvic acid was only detected after the secondary fermentations in wines from both regions. To our knowledge, this study is the first to investigate the influence of grape temperature on the oenological and organic acid characteristics of MCC wines in different regions and throughout different production stages.
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