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| citric acid | |
|---|---|
| Name | Citric acid |
| IUPAC name | 2-hydroxypropane-1,2,3-tricarboxylic acid |
| Other names | 2-hydroxy-1,2,3-propanetricarboxylic acid |
| Formula | C6H8O7 |
| Molar mass | 192.124 g·mol−1 |
| Melting point | 153 °C |
| Solubility | soluble in water |
citric acid
Citric acid is a weak organic acid widely found in Citrus fruits such as orange and Lemon. It functions as a key metabolite in the Krebs cycle and is a common additive in products regulated by agencies such as the Food and Drug Administration and the European Food Safety Authority. Major producers include firms competing in markets alongside Nestlé, Kraft Foods, Cargill, and Tate & Lyle, while industrial methods tie into processes developed by researchers at institutions like MIT and University of Illinois Urbana-Champaign.
Citric acid is a tricarboxylic acid with the systematic name 2-hydroxypropane-1,2,3-tricarboxylic acid. Its molecular geometry and stereochemistry have been characterized using techniques refined at laboratories such as Los Alamos National Laboratory and Lawrence Berkeley National Laboratory. Citric acid exhibits three pKa values measured by groups at National Institute of Standards and Technology and is commonly handled using buffers developed from salts like sodium citrate, prepared in facilities similar to those operated by BASF and Dow Chemical Company. Its chelating behavior for metal ions is comparable in discussions alongside ligands studied at Royal Society of Chemistry-supported projects.
Citric acid occurs naturally in Citrus species and other plants studied by botanists at institutions such as the Royal Botanic Gardens, Kew and the Smithsonian Institution. In cellular metabolism it is synthesized in the Krebs cycle in mitochondria, a pathway elucidated by researchers including Hans Krebs and taught in courses at Harvard University and University of Cambridge. Enzymes like citrate synthase and regulatory mechanisms characterized by laboratories at University of California, Berkeley mediate its production and turnover, which intersect with research on diseases investigated at the World Health Organization and Centers for Disease Control and Prevention.
Industrial production of citric acid is dominated by microbial fermentation using strains of Aspergillus niger and processes optimized in pilot plants run by companies such as ADM (company) and Cargill. Historical shifts from extraction from lemon and lime juices to fermentation were driven by innovations at firms like Hoffmann-La Roche and research at ETH Zurich. Downstream processing involves crystallization, evaporation, and purification techniques advanced in engineering departments at Massachusetts Institute of Technology and Imperial College London, with quality control guided by standards from ISO and pharmacopoeias like the United States Pharmacopeia.
Citric acid is used as a flavoring and preservative in foods produced by companies such as PepsiCo and The Coca-Cola Company, and as a chelating agent in formulations by Procter & Gamble and Unilever. It functions in pharmaceuticals approved by the European Medicines Agency and is a component in cleaning products marketed by Johnson & Johnson and industrial water treatment systems designed by firms like Veolia. In laboratories, it appears in buffers and reagent kits supplied by vendors such as Sigma-Aldrich and Thermo Fisher Scientific, and in biotechnology workflows at centers like Broad Institute.
Regulatory assessments by the Food and Drug Administration and European Food Safety Authority classify citric acid as safe at typical dietary levels, though occupational exposure controls adhere to guidelines from Occupational Safety and Health Administration and National Institute for Occupational Safety and Health. Allergic and irritant reports have been evaluated in clinical settings at hospitals like Mayo Clinic and Cleveland Clinic. Environmental considerations of large-scale production are addressed in sustainability initiatives by corporations such as Unilever and non-governmental organizations like Greenpeace, and life-cycle analyses have been published through collaborations with United Nations Environment Programme and academic groups at Yale University.
The acid was first isolated in crystalline form from lemon juice by the Swedish chemist Carl Wilhelm Scheele in the 18th century, with subsequent commercial extraction developed in Italy and Greece to supply apothecaries in cities like London and Paris. The transition to fermentation-based manufacture was pioneered by researchers collaborating with firms such as Hoffmann-La Roche and industrialized in regions including Midwest United States and Southeast Asia, shaping contemporary supply chains linked to ports like Rotterdam and Shanghai.
Category:Organic acids Category:Food additives