Abstract
Plant defense proteins (pathogenesis-related, or PR, proteins) have been implicated in allergenic reactions in humans. Grape PR-proteins are also known to be responsible for heat-induced haze and are susceptible to precipitation in the bottle. Changes in two defense proteins, a chitinase (CHV5) and a thaumatinlike (TL), were followed during the Champagne winemaking process, using Vitis vinifera L. cv. Pinot noir grape berries. Determination of chitinase activity indicated that the extraction yield of chitinases is at least 22% in the must with low pressing to make Champagne and that chitinase activity regularly diminishes during the winemaking process. SDS-PAGE electrophoresis of the must revealed that CHV5 and TL are the major proteins found in grape berries cv. Pinot noir. Using specific antibodies, changes in these two proteins during the Champagne winemaking process were followed. Western blotting indicated a regular disappearance of CHV5 and TL. TL did not seem to precipitate or hydrolyze but was absent in Champagne wine. CHV5 was likely fixed on the cell wall of Saccharomyces cerevisiae yeast (yeast lees) after alcoholic fermentation and on the cell wall of Oenococcus oeni bacteria after malolactic fermentation. Fragments of low molecular weight linked to CHV5 were observed, probably indicating that CHV5 had undergone proteolysis. This observation is in good agreement with the occurrence of an acid protease activity during the Champagne winemaking process.
- Vitis vinifera
- grape
- pathogenesis-related proteins
- chitinase
- thaumatin-like
- acid protease
- Saccharomyces cerevisiae
- yeast
- Oenococcus oeni
- Champagne
Acknowledgments: The authors wish to thank C. Hachet and A.M. Hamalian for their technical assistance and F. Mazeyrat-Gourbeyre for proofreading the manuscript. They also thank the Comité Interprofessionel du Vin de Champagne (CIVC, Epernay, France) for the generous gift of grape berries, musts and wines of Champagne. This work was supported by a grant from Europôl' Agro and Champagne Mumm Perrier-Jouët.
- Copyright 2003 by the American Society for Enology and Viticulture
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