Harvest (wine) of wine, winemakers would use the sugar and acid levels of the grape as a guide in determining ripeness. Early winemakers tasted the grapes to gauge ripeness. Modern winemakers use a refractometer to measure high sugar levels and °Brix or titration tests (using an indicator such as phenolphthalein) to determine the titratable acidity within the grape. In recent times there has been more of an emphasis on the "physiological" ripeness of the grape, usually in the form of tannins and other phenolics. Currently, tasting is the only way to measure tannin ripeness, which can take experience and skill to do
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