Citric acid is one of the most versatile ingredients in modern manufacturing, showing up in everything from soft drinks and skincare products to kidney stone treatments and household cleaners. Global production hit 2.39 million tons in 2020, and roughly 80% of it comes from fermenting sugars with a common mold called Aspergillus niger rather than squeezing it from citrus fruits. Here’s how it’s actually used across industries and in daily life.
Food and Beverages
The food industry is the single largest consumer of citric acid. Its appeal comes down to three properties: high solubility, extremely low toxicity, and a clean sour taste that complements fruit and berry flavors. In carbonated drinks and syrups, citric acid serves as an acidulant, typically added at concentrations between 1.5% and 5% depending on the flavor profile. It’s also the principal acid in jams, jellies, candy, desserts, wines, and frozen fruit products.
Beyond flavor, citric acid acts as a preservative by lowering pH. Many harmful bacteria, including the one responsible for botulism, cannot survive in acidic environments. Citric acid also binds to metal ions like copper and calcium, a process called chelation. This is what keeps cut fruits and vegetables from browning: the acid latches onto the copper that an enzyme called polyphenol oxidase needs to trigger discoloration, effectively disabling it. In fats, oils, and fat-containing foods, tiny amounts (0.005% to 0.02%) boost the performance of antioxidants and help maintain quality in frozen products by inactivating enzymes that cause spoilage.
The FDA classifies citric acid as “generally recognized as safe” (GRAS) with no specific concentration limits beyond standard good manufacturing practice. That’s a reflection of how well-studied and low-risk it is as a food additive.
Cleaning and Descaling
Citric acid’s chelating ability makes it a natural descaler. Limescale, the white crusty buildup inside kettles, coffee makers, and showerheads, is primarily calcium carbonate. Citric acid dissolves it by binding to the calcium ions and pulling them away from the deposit, breaking the mineral structure into a soluble complex that rinses away with water.
This same mechanism works on hard water stains, soap scum, and rust. Because it’s biodegradable and far less corrosive than hydrochloric or sulfamic acid, citric acid has become a popular ingredient in “green” cleaning products. You can buy it as a pure powder for DIY cleaning solutions, and it’s already in many commercial dishwasher rinse aids, bathroom sprays, and appliance descalers.
Kidney Stone Prevention
Citrate, the form citric acid takes once it enters your bloodstream, plays a critical role in preventing calcium-based kidney stones. It works through two mechanisms. First, citrate binds to calcium in urine, forming soluble complexes that keep calcium from crystallizing into stones. Second, it acts as a base equivalent, helping your kidneys excrete alkali without pushing urine pH dangerously high. Together, these effects make citrate one of the body’s built-in defenses against stone formation.
When urine citrate levels are too low, a condition called hypocitraturia, the risk of calcium stones rises significantly. Doctors often prescribe potassium citrate supplements to restore those levels. The compound works by creating a mild systemic alkalinization, which signals the kidneys to pull less citrate back from urine, leaving more of it available to bind calcium. People prone to recurrent kidney stones are sometimes also encouraged to increase dietary citrate through lemon water or other citrus-rich drinks, though supplemental forms deliver more predictable doses.
Skincare and Cosmetics
Citric acid belongs to the alpha hydroxy acid (AHA) family, a group of water-soluble acids used in skincare for surface-level exfoliation. Applied topically, it helps loosen the bonds between dead skin cells, promoting turnover that can reduce fine lines, smooth texture, and improve skin tone over time. It’s a milder AHA compared to glycolic acid, which makes it common in products designed for sensitive skin or as a supporting ingredient rather than the primary active.
Cosmetic formulators also rely on citric acid as a pH adjuster. Many active ingredients in serums, cleansers, and creams only work within a specific pH range, and small amounts of citric acid bring the formula into that window. You’ll find it on the ingredient list of products that don’t advertise any exfoliating benefit at all, simply because it’s there to keep the pH stable.
Pharmaceuticals
If you’ve ever dropped an effervescent tablet into a glass of water and watched it fizz, you’ve seen citric acid at work. Those tablets contain citric acid alongside sodium bicarbonate (baking soda). When water hits the tablet, the acid reacts with the bicarbonate to release carbon dioxide gas, which rapidly breaks the tablet apart and disperses the medication into solution. This design is especially useful for drugs that are hard to swallow in large doses, medications that irritate the stomach lining (like aspirin), or formulations where rapid absorption matters, such as pain relievers.
Citric acid also shows up as a stabilizer and pH buffer in liquid medications, IV solutions, and anticoagulant formulas used in blood banking. Its chelating properties help maintain drug potency by binding trace metals that could otherwise degrade active ingredients over time.
How It’s Made
Although citric acid occurs naturally in citrus fruits, lemons contain about 5% to 8% by weight, virtually all commercial citric acid is produced through industrial fermentation. The workhorse organism is Aspergillus niger, a black mold that converts sugars (usually from corn or sugarcane molasses) into citric acid under carefully controlled conditions. About 80% of global production uses submerged fermentation, where the mold grows in large liquid tanks. The resulting acid is chemically identical to what you’d find in a lemon, and the final product is purified to food-grade or pharmaceutical-grade standards.
Some people wonder whether “natural” citric acid from fruit differs from the fermented version. Chemically, the molecule is the same regardless of its source. The distinction matters mainly for organic certification or labeling purposes, where some standards require citric acid derived from non-GMO feedstocks or specific production methods.