Ripeness is the physiologic state when the grapes accumulate sugars and their acidity drops, making it the ideal moment to pick the grapes to make wine.
Grapes are considered to be at optimal ripeness for picking when the sugar concentration is between 250 and 330 grammes of sugar per litre, and the acidity has dropped.
Grapes ripen between the veraison and physiological ripeness. Before veraison, the grape berries behave like leaves and undergo photosynthesis. After veraison the berries change colour, they gain weight, accumulate sugars and aromas and their acidity starts to fall. The sugars are developed mostly through the photosynthesis of the plant’s leaves and partly from the vine’s own reserves. These sugars are mostly glucose and fructose. The acidity is made up of two acids: Malic and Tartaric acid. During the ripening process it is the malic acid that is reduced; the absolute tartaric acid content remains the same, but is diluted as the grapes gain weight.
Other curiosities in the category: Vineyard