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
The Grapes of Wrath sums up the book's influence: ""The Grapes of Wrath" may well be the most thoroughly discussed novel – in criticism, reviews, and college classrooms – of 20th century American literature." "The Grapes of Wrath" is referred to as a Great American Novel. At the time of publication, Steinbeck's novel "was a phenomenon on the scale of a national event. It was publicly banned and burned by citizens, it was debated on national radio; but above all, it was read." According to "The New York Times," it was the best-selling book of 1939 and 430,000 copies had been printed by February