Fizzy Drink With a Fuzzy Fungus

Carbonated (fizzy) drinks are a mixture of water, fruit juice, flavorings, and preservatives such as benzoic or citric acid. If the drink has citric acid then it is probably a microbial product. Most citric acid is made by fermenting a sugar, like molasses, with the mold called Aspergillus niger. The specific strain of the fungus used by soda companies is kept secret. Having a precise combination of sugar type and convention, pH, trace metal content, aeration, and salt concentration, can produce the perfect amount of citric acid. The easiest fermentation method used is called the submerged process. Fermintation is carried out in to towers made of stainless steel. The hairy part of the fungus (mycelium) develops into small pellets. This process takes about 7-10 days. The culture broth is then filtrated and the citric acid is extracted and crystallized out and sent to beverage industries to produce your favorite soda!