Carbon dioxide All gas 'Contains added carbon dioxide' The writing on bottles of sparkling mineral water or drinks has never shocked anyone. For wine, however, things are different. Carbon dioxide (CO2) develops naturally in wine as a result of different fermentation processes and any 'external' addition must be declared on the label. CO2 is clearly evident in sparkling and semi-sparkling wines, but is also present in small doses in still wines and serves to balance the wines, while keeping the bouquet and tastes more alive and fresher. But in this case the old saying is still true 'too much is too much': the touch of carbon dioxide can be pleasant when tasting a sparkling or semi-sparkling wine and comes across as a note of freshness. But it becomes unpleasant if it is too noticeable, creating a sort of rejection and, what is more, making it difficult to drink the wine, exactly like drinking drinks which are too gassy.