Citric acid is a common compound in many products, from beverages to cleaning supplies. A frequent question concerns its production, specifically the idea that it comes from “black mold.” This misunderstanding often arises from a lack of awareness about modern industrial processes. This article clarifies how citric acid is produced, emphasizing the precision and safety of contemporary manufacturing.
The Truth About Citric Acid Production
While citric acid is naturally present in citrus fruits, industrial production has shifted from direct fruit extraction. Early commercial production isolated citric acid from lemon juice, but this became economically unfeasible for large-scale demand. Today, most citric acid is produced through microbial fermentation.
This process involves feeding specific microorganisms a sugar-rich medium, such as molasses or corn starch. The microorganisms metabolize these sugars, converting them into citric acid. This controlled industrial process occurs in large bioreactors under optimized conditions of temperature, pH, and aeration. The resulting citric acid is then extracted and purified.
Understanding Aspergillus niger
The microorganism predominantly used in industrial citric acid production is a specific strain of filamentous fungus called Aspergillus niger. This fungus is indeed responsible for what is colloquially known as “black mold” when it appears on certain fruits or in damp environments. However, the Aspergillus niger strains used industrially are selected and cultivated to be non-pathogenic and efficient citric acid producers.
Aspergillus niger is chosen for its high citric acid yields and tolerance for acidic conditions, which prevents contamination during fermentation. The fungus metabolizes sugars, excreting citric acid into the surrounding liquid. After fermentation, the fungal biomass is separated through filtration. The remaining liquid then undergoes extensive purification, including precipitation, crystallization, and drying, to yield pure citric acid without mold residue.
Safety and Common Uses of Citric Acid
Manufactured citric acid is widely recognized as safe for consumption and use across various industries. Regulatory bodies, such as the U.S. Food and Drug Administration (FDA), affirm citric acid as “Generally Recognized As Safe” (GRAS) for use as a direct human food ingredient. This designation indicates experts consider it safe under its intended conditions of use. The purification process ensures the final product is a pure chemical compound, identical in molecular structure to natural citric acid.
Citric acid serves many functions due to its acidic and chelating properties. In the food and beverage industry, it acts as a flavoring agent, providing a tart taste, and as a preservative by inhibiting microbial growth and preventing oxidation. It is commonly found in soft drinks, candies, canned goods, and dairy products. Beyond food, citric acid is used in pharmaceuticals for stabilization and to enhance medicine taste, in cosmetics, and as a cleaning agent for mineral deposit removal. Approximately 70% is used in food and beverages, 20% in pharmaceuticals and dietary supplements, and 10% in cleaning agents and other industrial applications.