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 they provide solid evidence of wine making, they don't necessarily provide evidence of how the wine was made and if the modern concept of pressing (i.e. extracting juice from the skins and separating it from the skins and seeds) was used. Winemaking in ancient Egypt probably used people's feet for crushing and pressing the grapes, but tomb paintings excavated at Thebes showed that the ancient Egyptians developed some innovations to their wine presses-such as the use of long bars hanging over the treading basins and straps that the workers could hold onto while treading. Hieroglyph and paintings also showed the