Citric acid is an organic compound with the formula C₆H₈O₇. It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in the metabolism of all aerobic organisms. Additional technical information: molecular weight 192.12 g mol, commonly encountered as the monohydrate crystalline solid, highly soluble in water and sparingly soluble in ethanol, and it has three carboxylic acid groups with pKa values near 3.13, 4.76 and 6.40 at 25 degrees Celsius. Citric acid is an effective chelating agent for divalent metal ions and functions as a buffering agent in weakly acidic systems; it participates in esterification and dehydration chemistry under acidic or thermal conditions and is produced industrially at large scale by fermentation of carbohydrate feedstocks and by chemical synthesis for specialty applications.
Parent: Citric Acid
Typical commercial specification ranges for high purity grades are expressed on a dry basis and vary by intended use; representative values are assay 99.0 to 99.9 percent, moisture content under 0.5 percent for anhydrous material and approximately 7.5 to 8.5 percent water for the monohydrate form, total ash below 0.05 percent, sulfate and chloride each commonly controlled to low ppm levels, and heavy metals limited to single digit parts per million with lead and arsenic limits often set at 5 ppm and 1 ppm respectively for food and pharmaceutical grades. Common organic related compounds and byproducts that may be present at trace to low percent levels depending on production and purification route include isocitric acid, aconitic acid, malic acid and residual sugars or fermentation metabolites; inorganic related species can include sodium, potassium or calcium citrate salts formed during neutralization steps. Final impurity profiles are governed by grade standards such as USP, EP or FCC and by customer specifications.
Citric acid is used as a food acidulant and flavor enhancer, preservative by pH control and metal chelation, buffering agent in beverages and pharmaceuticals, effervescence agent in tablet formulations, chelating and scale removal agent in cleaners, pH adjuster and stabilizer in cosmetic formulations, and as a raw material or intermediate in chemical processes.
At typical dietary and formulation concentrations citric acid is generally recognized as safe for consumption and topical use, though concentrated solutions can irritate skin, eyes and mucous membranes and excessive oral intake may cause gastrointestinal discomfort; products intended for medical or cosmetic use should follow regulatory limits and label guidance.
No, Lemon juice contains a high concentration of citric acid but it is a complex aqueous mixture that also contains water, sugars, other organic acids, vitamins, minerals and volatile flavor compounds; citric acid in lemon juice is a component rather than the sole constituent.
In skin care citric acid acts as a pH adjuster, chelating agent and mild alpha hydroxy acid that can promote exfoliation and improve product texture; it can increase cell turnover at controlled concentrations but may cause irritation or sensitization if used at high concentrations or without proper formulation and sun protection.
