Trisodium citrate

Trisodium citrate is a chemical compound with the molecular formula Na3C6H5O7. It is often called sodium citrate, though that name can describe any of the three sodium salts of citric acid. This substance has a saline and mildly tart taste. It also functions as a mild base. A base is a substance that is the opposite of an acid.

This compound is highly versatile. It plays important roles in food science, medicine, and industrial cleaning.

In the food industry, trisodium citrate is a common additive known as E331. It serves as a flavoring agent or a preservative. You might taste its tartness in club soda, wine, or various drink mixes. It is also found in many dairy products like yogurt, ice cream, and milk powder. It appears in many other foods too, such as jams, sweets, gelatin mix, and even butter chicken.

It is even an ingredient in bratwurst.

One of its most important roles in food is as an emulsifying stabilizer. This is especially useful when making processed cheese. When cheese melts, the fats often try to separate, which makes the cheese feel greasy. Trisodium citrate stops this separation. It allows the cheese to melt smoothly, which makes it a great topping for nachos. This chemical process also helps maintain the physical gel microstructure in many dairy products.

Trisodium citrate also acts as a buffering agent. A buffer is a substance that resists changes in pH, which is the measure of how acidic or basic a liquid is. As a conjugate base of a weak acid, the citrate ion can regulate acidity. For example, it is used to control acidity in gelatin desserts. In a solution of 5 g/100 ml of water at 25 °C, the pH range is between 7.5 and 9.0. This ability to regulate pH is why it is found in milk containers used with coffee machines.

In medicine, trisodium citrate has a very important history. In 1914, the Belgian doctor Albert Hustin and the Argentine physician Luis Agote used it as an anticoagulant. An anticoagulant is a substance that prevents blood from clotting. This was a major step for blood transfusions. In 1915, Richard Lewisohn determined the correct concentration needed to make this safe.

Today, it is still used in blood banks and in tubes used to collect blood.

This compound works in the blood through a process called chelation. The citrate ion chelates calcium ions by forming calcium citrate complexes. This process disrupts the mechanism that causes blood to clot. Recently, it has been used as a locking agent in hemodialysis lines. This is done instead of using heparin because it has a lower risk of systemic anticoagulation. Researchers also studied its effects on physical performance. In 2003, Ööpik et al. showed that using 0.5 g/kg of body weight improved 5 km running times by 30 seconds.

Trisodium citrate is also used to treat various health issues. It can relieve discomfort from urinary-tract infections like cystitis. It can also reduce acidosis in cases of distal renal tubular acidosis. It serves as an osmotic laxative and is a major component of the WHO oral rehydration solution. Doctors also use it as an antacid. This is often done before anesthesia for caesarian section procedures to reduce risks from gastric contents. You can even find it in your home when you dissolve antacids like Alka-Seltzer in water.

Beyond food and medicine, this chemical is useful for cleaning. It is an effective agent for removing carbonate scale from boilers. A major benefit is that it can do this without taking the boilers out of operation. It is also used to clean automobile radiators. In a laboratory setting, it is a component in Benedict's qualitative solution. This solution helps scientists detect reducing sugars like glucose during organic analysis. It can also be used to prepare inorganic metal citrates, such as copper citrate.