Trisodium citrate has the chemical formula of Na₃C₆H₅O₇. It is sometimes referred to simply as "

sodium citrate Sodium citrate may refer to any of the sodium salts of citric acid (though most commonly the third): * Monosodium citrate * Disodium citrate * Trisodium citrate The three forms of salt are collectively known by the E number E331. Applications ...

", though sodium citrate can refer to any of the three

sodium salts Sodium salts are salts composed of a sodium cation and the conjugate base anion of some inorganic or organic acids. They can be formed by the neutralization of such acids with sodium hydroxide. Categorization Sodium salts can be categorized in ...

citric acid Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. 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 ...

. It possesses a saline, mildly tart flavor, and is a mild

alkali In chemistry, an alkali (; from ar, القلوي, al-qaly, lit=ashes of the saltwort) is a basic, ionic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a ...

Applications

Foods

Sodium citrate is chiefly used as a

food additive Food additives are substances added to food to preserve Taste, flavor or enhance taste, appearance, or other sensory qualities. Some additives have been used for centuries as part of an effort to preserve food, for example vinegar (pickling), sal ...

, usually for flavor or as a

preservative A preservative is a substance or a chemical that is added to products such as food products, beverages, pharmaceutical drugs, paints, biological samples, cosmetics, wood, and many other products to prevent decomposition by microbial growth or b ...

. Its

E number E numbers ("E" stands for "Europe") are codes for substances used as food additives, including those found naturally in many foods such as vitamin C, for use within the European Union (EU) and European Free Trade Association (EFTA). Commonly ...

is E331. Sodium citrate is employed as a flavoring agent in certain varieties of

club soda Club soda is a manufactured form of carbonated water, commonly used as a drink mixer. Sodium bicarbonate, potassium sulfate, potassium bicarbonate, potassium citrate, or sodium citrate is artificially added to replicate constituents commonly fo ...

. It is common as an ingredient in

bratwurst Bratwurst () is a type of German sausage made from pork or, less commonly, beef or veal. The name is derived from the Old High German ''Brätwurst'', from ''brät-'', finely chopped meat, and ''Wurst'', sausage, although in modern German it is o ...

, and is also used in commercial

ready-to-drink Ready to drink (often known as RTD) packaged beverages are those sold in a prepared form, ready for consumption. Examples include iced tea (prepared using tea leaves and fruit juice) and alcopops (prepared by mixing alcoholic beverages with frui ...

beverages and

drink mix A drink mix is a processed-food product, designed to mix usually with water to produce a beverage resembling fruit juice or soda in flavor. Another type of drink mix is represented by products that are mixed into milk. It is traditionally made i ...

es, contributing a tart flavor. It is found in gelatin mix, ice cream, yogurt, jams, sweets, milk powder, processed cheeses, carbonated beverages, and wine, amongst others. Sodium citrate can be used as an emulsifying stabilizer when making cheese. It allows the cheese to melt without becoming greasy by stopping the fats from separating.

Buffering

As a

conjugate base A conjugate acid, within the Brønsted–Lowry acid–base theory, is a chemical compound formed when an acid donates a proton () to a base—in other words, it is a base with a hydrogen ion added to it, as in the reverse reaction it loses a ...

of a weak acid, citrate can perform as a

buffering agent A buffer solution (more precisely, pH buffer or hydrogen ion buffer) is an aqueous solution consisting of a mixture of a weak acid and its conjugate base, or vice versa. Its pH changes very little when a small amount of strong acid or base is ...

acidity regulator Acidity regulators, or pH control agents, are food additives used to change or maintain pH (acidity or basicity). They can be organic or mineral acids, bases, neutralizing agents, or buffering agents. Typical agents include the following acids ...

, resisting changes in pH. It is used to control

acid In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a se ...

ity in some substances, such as

gelatin dessert Gelatin desserts (also Jelly or Jello) are desserts made with a sweetened and flavoured processed collagen product (gelatin). This kind of dessert was first recorded as jelly by Hannah Glasse in her 18th-century book ''The Art of Cookery'', a ...

s. It can be found in the milk minicontainers used with coffee machines. The compound is the product of

antacid An antacid is a substance which neutralizes stomach acidity and is used to relieve heartburn, indigestion or an upset stomach. Some antacids have been used in the treatment of constipation and diarrhea. Marketed antacids contain salts of alu ...

s, such as

Alka-Seltzer Alka-Seltzer is an effervescent antacid and pain reliever first marketed by the Dr. Miles Medicine Company of Elkhart, Indiana, United States. Alka-Seltzer contains three active ingredients: aspirin (acetylsalicylic acid) (ASA), sodium bicarbo ...

, when they are dissolved in water. The pH of a solution of 5 g/100 ml water at 25 °C is 7.5 – 9.0. It is added to many commercially packaged dairy products to control the pH impact of the gastrointestinal system of humans, mainly in processed products such as cheese and yogurt, although it also has beneficial effects on the physical gel microstructure.

Chemistry

Sodium citrate is a component in Benedict's qualitative solution, often used in organic analysis to detect the presence of reducing sugars such as

glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...

Medicine

In 1914, the

Belgian Belgian may refer to: * Something of, or related to, Belgium * Belgians, people from Belgium or of Belgian descent * Languages of Belgium, languages spoken in Belgium, such as Dutch, French, and German *Ancient Belgian language, an extinct languag ...

doctor

Albert Hustin Albert Hustin (1882–1967) was a Belgian medical doctor. Hustin was born in Ethe and died in Uccle (Uccle Brussels – Belgium). In 1914, he was the first person to successfully practice non-direct blood transfusions with sodium citrate used ...

and the

Argentine Argentines (mistakenly translated Argentineans in the past; in Spanish (masculine) or (feminine)) are people identified with the country of Argentina. This connection may be residential, legal, historical or cultural. For most Argentines, ...

physician and researcher Luis Agote successfully used sodium citrate as an

anticoagulant Anticoagulants, commonly known as blood thinners, are chemical substances that prevent or reduce coagulation of blood, prolonging the clotting time. Some of them occur naturally in blood-eating animals such as leeches and mosquitoes, where t ...

blood transfusion Blood transfusion is the process of transferring blood products into a person's circulation intravenously. Transfusions are used for various medical conditions to replace lost components of the blood. Early transfusions used whole blood, but mo ...

s, with Richard Lewisohn determining its correct concentration in 1915. It continues to be used today in blood-collection tubes and for the preservation of

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the cir ...

blood bank A blood bank is a center where blood gathered as a result of blood donation is stored and preserved for later use in blood transfusion. The term "blood bank" typically refers to a department of a hospital usually within a Clinical Pathology laborat ...

s. The citrate ion

chelates Chelation is a type of bonding of ions and molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. These ligands ar ...

calcium ions in the blood by forming

calcium citrate Calcium citrate is the calcium salt of citric acid. It is commonly used as a food additive ( E333), usually as a preservative, but sometimes for flavor. In this sense, it is similar to sodium citrate. Calcium citrate is also found in some die ...

complexes, disrupting the blood clotting mechanism. Recently, trisodium citrate has also been used as a locking agent in vascath and haemodialysis lines instead of heparin due to its lower risk of systemic anticoagulation. In 2003, Ööpik et al. showed the use of sodium citrate (0.5 g/kg body weight) improved running performance over 5 km by 30 seconds. Sodium citrate is used to relieve discomfort in urinary-tract infections, such as

cystitis A urinary tract infection (UTI) is an infection that affects part of the urinary tract. When it affects the lower urinary tract it is known as a bladder infection (cystitis) and when it affects the upper urinary tract it is known as a kidney ...

, to reduce the acidosis seen in distal

renal tubular acidosis Renal tubular acidosis (RTA) is a medical condition that involves an accumulation of acid in the body due to a failure of the kidneys to appropriately acidify the urine. In renal physiology, when blood is filtered by the kidney, the filtrate p ...

, and can also be used as an osmotic

laxative Laxatives, purgatives, or aperients are substances that loosen stools and increase bowel movements. They are used to treat and prevent constipation. Laxatives vary as to how they work and the side effects they may have. Certain stimulant, lubri ...

. It is a major component of the WHO oral rehydration solution. It is used as an antacid, especially prior to anaesthesia, for

caesarian section Caesarean section, also known as C-section or caesarean delivery, is the surgical procedure by which one or more babies are delivered through an incision in the mother's abdomen, often performed because vaginal delivery would put the baby or ...

procedures to reduce the

risks In simple terms, risk is the possibility of something bad happening. Risk involves uncertainty about the effects/implications of an activity with respect to something that humans value (such as health, well-being, wealth, property or the environm ...

associated with the aspiration of gastric contents.

Boiler descaling

Sodium citrate is a particularly effective agent for removal of carbonate scale from boilers without removing them from operation and for cleaning automobile radiators.

References

{{reflist Food acidity regulators Citrates Organic sodium salts Chelating agents E-number additives