Acids in wine ripened grapes. While concentration varies among grape varieties, it is usually found in higher levels with red wine grapes. The acid is created as a byproduct of the metabolization of nitrogen by yeast cells during fermentation. The combination of succinic acid with one molecule of ethanol will create the ester mono-ethyl succinate responsible for a mild, fruit aroma in wines. Acidity is highest in wine grapes just before the start of "veraison", which ushers in the ripening period of the annual cycle of grape vines. As the grapes ripen, their sugar levels increase and their acidity levels decrease. Through the
Wine Grapes to a connection between the Italian variety Primitivo and the Croatian wine grape Crljenak Kaštelanski. After years of research and DNA testing of vines from vineyards across the globe, a single 90-year-old grape vine from the garden of an elderly lady in Split, Croatia provided the evidence to show that Zinfandel was originally a Croatian grape known as "Tribidrag" that had been cultivated in Croatia since the 15th century. Other findings reported in "Wine Grapes" include the discovery of several species of Malvasia grapes growing in central and southern Italy are actually the Spanish wine grape Tempranillo and that Cabernet