Citric Acid

Until the 1920s, Italy held a virtual monopoly on the production of citric acid, accounting for 90 percent of the world's total production with low-grade lemons. When American chemists discovered that a common black mold, Aspergillus niger, secreted citric acid, they broke Italy's hold on the market by producing enough cheap citric acid to bring prices down from a dollar a pound to only about 25 cents.