citric acid

Question

For what it's worth I found the following description of citric acid production at http://www.techno-preneur.net/timeis/andhra/invopp/ChemicaL/cCitric_acid.htm. It says something about wheat under "manufacturing process" but I am not sure if it is relevant to pesach? Here goes... CITRIC ACID --------------------------------------------------------- Citric acid is found in almost all plant and animal tissues. The citric acid cycle, also called the Krebs cycle or tricarboxylic cycle, is pivotal in the oxidation of sugars and acetates to carbon dioxide and water, releasing energy for physiological functions. Citrus fruits contain citric acid in large quantities, ranging from 5% in the fruit to about 9% in the juice. The sour taste of lemon juice is mainly due to the presence of citric acid (5 to 8 %) and partly due to the presence of vitamin C. Citric acid can be manufactured by three different processes: Extraction from citrus fruits Synthesis Fermentation It is also used in the manufacture of synthetic soft drinks, confectionery, other processed food products, drugs and pharmaceuticals, citrates and effervescent salts, etc. Fermentation is the most economical and widely used process for commercial production of citric acid since the 1920s. More than 90% of the citric acid produced in the world is obtained by fermentation. The widely used micro - organism used for citric acid production is Aspergillus niger. Manufacturing process In commercial production of citric acid based on this process, certain strains of Aspergillus niger, when grown on the surface of a sucrose and salt solution, produce significant amounts of citric acid. Variations of this surface culture technique still account for a substantial portion of citric acid production in the world. The surface fermentation methodology consists of inoculating with spore of Aspergillus niger, shallow aluminium or stainless pans containing sugar solution along with sources of assimilable nitrogen, phosphate, magnesium and various trace minerals. These pans are stacked vertically in a chamber. Growth of the mold occurs on the solution surface forming a rubbery, con - voluted mycelial mass. Air is passed over the surface which provides oxygen and controls temperature by evaporative cooling. Due to its relatively low cost, molasses has proven to be a preferred source of sugar for microbial production. Since it is a by-product of sugar refining, the quality of molasses varies considerably, and not all types are suitable for citric acid production. Beet molasses are preferred to sugarcane, but there are considerable yield variations within each type. Beet molasses must be treated prior to use to improve yield. Treatment may consist of ion exchange, chemical precipitation or chelation of metallic ions. Sugar syrup can also be used as substrate. Glucose syrups can be prepared from wheat, corn, potato or other starch. The sugar content of the syrup can vary from about 10 to 25, by percentage of weight. Fermentation can continue for about ten to 12 days. The theoretical yield from 100 kg of sucrose is 123 kg of citric monohydrate or 112 kg of anhydrous acid. However, the Aspergillus niger uses some sugar for growth and respiration, and the actual yield varies between 57 & 77% of the theoretical yield, depending on such factors as substrate purity, strain of organism used, and control of fermentation.