White wine the death knell of northern viticulture. The vine disappeared from northern Germany and Baden, and the maximum altitude for viticulture descended to 220 metres. Hans-Jürgen Otto noted that: "all the vineyards suffered and decreased in area". In England the vine also disappeared. The less early vineyards preferred to select white varieties of grapes because, even if unripe, white grapes allowed wine that was a little sour to still be consumable, while red grapes do not give enough colour and green tannins make the wine bitter. The interruption of the fermentation by a cold winter led to the discovery of the
White wine salts with the tartaric acid: Potassium bitartrate and the neutral calcium tartrate at the pH of the wine. For these, when their solubility threshold is reached, they settle and contribute to de-acidify the wort. In the southern regions where acidity is sometimes a little lacking this may be a cause of failure of extra acidity. White wine is made from white or black grapes (but always with white flesh, the grapes with coloured flesh are called "Teinturier" meaning coloured juice). Once harvested, the grapes are pressed and only the juice is extracted which is called wort. The wort is put