Biochemical comparison of two grape varieties differing in juice acidity

• P. DIAKOU ^[1] ; A. MOING ^[2] ; L. SVANELLA ^[2] ; N. OLLAT ^[2] ; D.B. ROLIN ^[3] ; M. GAUDILLERE ^[1] ; J.P. GAUDILLERE ^[4]
  1. [1] Station de PhysiologieVégétale. Institut National de la Recherche Agronomique
  2. [2] Unité de Recherches sur les Espèces Fruitières et la Vigne. Institut National de la Recherche Agronomique
  3. [3] Laboratoire Métabolisme et Développement des Plantes, Université Victor Segalen Bordeaux 2
  4. [4] Unité d'Agronomie. Institut National de la Recherche Agronomique

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• Localización: Australian journal of grape and wine research, ISSN 1322-7130, Vol. 3, Nº 3, 1997, págs. 31-40
• Idioma: inglés
• Texto completo no disponible (Saber más ...)
• Resumen

  • The winegrape cv. Cabernet Sauvignon and the tablegrape cv. Gora Chirine (both Vitis vinifera L.) differ in the acidity of their berry juice. The changes in pH, titratable acidity and the concentration of compounds of the berry juice were measured from 20–30 d before veraison to harvest on plants cultivated in the glasshouse. The difference in acidity between the juice of the two varieties appeared before veraison. At harvest, the berry juice of Gora Chirine had a pH of 5.2 and titratable acidity (TA) of 32 meq/L while that of Cabernet Sauvignon had a pH of 3.2 and TA of 150 meq/L. To evaluate cellular compartmentation in the berry pericarp, vacuolar pH was measured on intact berries at two growth stages, using 13C nuclear magnetic resonance (NMR). Vacuolar pH did not differ significantly between the two cvs. The lower TA of Gora Chirine juice could be attributed to lower concentrations of all three major acids, malic, tartaric and citric, and to a higher concentration of potassium. At veraison, the malic acid concentration in the berry juice of Cabernet Sauvignon was about seven times higher than that of Gora Chirine. The accumulation of hexoses, especially glucose, occurred earlier during the berry growth cycle in Gora Chirine than in Cabernet Sauvignon. The osmotic potential of the Gora Chirine juice, before veraison, was lower than could have been expected because of low acidity. This was due to the compensatory effect of early accumulation of glucose. Amino acid concentration was significantly higher in Gora Chirine than in Cabernet Sauvignon, especially just before veraison. The role of organic acids in berry acidity and osmotic potential, and various metabolic processes that may lead to the difference in organic acid concentration, are discussed.