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
History of the wine press from olives. This press would entail laying the grapes out underneath several planks of wood and then weighing the planks down with rocks to press the juice out from the grapes. The wine made from these rudimentary pressing wasn't held in high esteem by the Greeks, often tainted with impurities and having a short shelf life. Much more prized was the wine produced from "free run" juice that was released by the grapes under their own weight before any treading or pressing. This wine was believed to be the most pure and was often used for medicinal purposes. In the