The most widely used method for synthesizing citric acid was discovered by an American chemist named James Currie in 1917 to address the lack of citrus imports caused by the First World War. This method requires the cultivation of the fungus “Aspergillus niger”. This mold is quite common in nature, but major citric acid companies use special strains to increase the fungus' production of citric acid. This method involves substances that contain glucose such as simple sugar or molasses being fed to the mushroom. The fungus uses glucose as food and produces citric acid and carbon dioxide as waste products. When the maximum concentration of citric acid is reached, the mold will be filtered out. A base solution, such as calcium hydroxide, would then be added to the solution to create a salt, in the case of calcium hydroxide, the salt, calcium citrate, will be produced. The formula of calcium citrate is Ca3(C6H5O7)2. The equation for the reaction of calcium hydroxide and citric acid is (3Ca(OH)2 + 2H3C6H5O7 -> Ca3(C6H5O7)2 + 3H2). After the salt has been filtered, the citric acid is regenerated from the salt by adding an acid. Sulfuric acid is commonly used in this process. The equation for reforming citric acid from the salt, calcium citrate, is (3H2SO4 + Ca3(C6H5O7)2 -> H3C6H5O7 + 3CaSO4). The additional product, calcium sulfate, is a precipitate and can be filtered out leaving an isolated citric acid as the only remaining product. The two widely used fermentation methods are submerged and surface fermentation. They are relatively similar with the only difference being that in surface fermentation the fungus would grow on top of the glucose fed to it. Submerged ferment...... in the center of the paper ......ar. 2012. “How to Extract Citric Acid from Citrus Juice.” Gomestic. 09 August 2010. Web. 03 March 2012. "Manufacturer and supplier of Guar | Thickeners | Gums | Gelling agents." Chemtotal Pty Ltd.Web. March 07, 2012. "pH Scale." Chemical book. Elmhurst. Network. 07 March 2012. Robinson, Allan. "How to make citric acid". EHow. Demand Media, July 19, 2009. Web. March 3, 2012. “Standardizing a Sodium Hydroxide Solution.” CSIP Student Information Request Projects. Cornell"Yeast". Gluten-free diet. Network. 03 March. 2012. .