What are the ingredients in sodium citrate?

Sodium citrate is a versatile compound found in countless products, from processed cheese to soft drinks. While its applications are diverse, its creation is quite simple, stemming from a neutralization reaction between citric acid and a sodium-containing base.

Quick Summary

Sodium citrate is a sodium salt of citric acid, commonly manufactured by neutralizing citric acid with a sodium base such as sodium hydroxide or sodium carbonate. The process results in a white, crystalline powder used as an emulsifier, preservative, and acidity regulator.

Key Points

• Core Components: Sodium citrate is made from a neutralization reaction between citric acid and a sodium-containing base, like sodium hydroxide.

• Natural Origin: The citric acid used in the process can be derived naturally from citrus fruits or produced commercially through microbial fermentation.

• Manufacturing Process: Industrial production involves fermenting a sugar source to get citric acid, which is then neutralized with a sodium base to form sodium citrate.

• Forms of the Salt: There are three types—monosodium, disodium, and trisodium citrate—with trisodium citrate being the most common.

• Versatile Functions: Its purpose varies from acting as an emulsifier in cheese to an anticoagulant in stored blood.

• Food Safety: The FDA has deemed sodium citrate as Generally Recognized As Safe (GRAS) for use in food.

Understanding the Core Components

Sodium citrate is not a single chemical but rather a group of sodium salts derived from citric acid. The most common form, trisodium citrate, has the chemical formula $Na₃C₆H₅O₇$. Its two main components are citric acid and a sodium-containing base, and it is the reaction between these two that defines the ingredients of sodium citrate.

The Role of Citric Acid

Citric acid ($C₆H₈O₇$) is a weak organic acid that occurs naturally in citrus fruits like lemons and oranges. It is also produced commercially through microbial fermentation, most often using the fungus Aspergillus niger to process sugar feedstocks like molasses. In the production of sodium citrate, this citric acid provides the citrate portion of the final salt.

The Sodium Source

The sodium component comes from a strong base, typically either sodium hydroxide ($NaOH$) or sodium carbonate ($Na₂CO₃$). The base reacts with the citric acid in a neutralization reaction, effectively replacing the hydrogen ions in the citric acid with sodium ions.

The Chemical Reaction Explained

During production, a sodium base is added to a solution of citric acid until a specific pH is reached, completing the neutralization. For the production of trisodium citrate, the reaction is as follows: $C₆H₈O₇ + 3NaOH → Na₃C₆H₅O₇ + 3H₂O$

This simple formula shows that the ingredients of sodium citrate are citric acid and a sodium base, which combine to form sodium citrate and water. The resulting sodium citrate is then isolated through a process of evaporation and crystallization.

Sodium Citrate: A Closer Look at the Manufacturing Process

While the core reaction is straightforward, the industrial manufacturing process involves several steps to ensure a high-purity, stable final product. The process often starts with the fermentation of a carbohydrate source to produce citric acid.

1. Fermentation: Microorganisms, like Aspergillus niger, ferment a sugar substrate to produce citric acid.
2. Purification: The crude citric acid solution is purified through filtration and crystallization.
3. Neutralization: The purified citric acid is reacted with a sodium compound, such as sodium hydroxide or sodium carbonate, to create sodium citrate.
4. Crystallization and Recovery: The sodium citrate solution is concentrated, and the resulting crystals are harvested, washed, and dried.

Types of Sodium Citrate

Based on the extent of neutralization, there are three types of sodium citrate, which fall under the food additive code E331:

• Monosodium Citrate ($NaH₂C₆H₅O₇$): Only one hydrogen ion is replaced by a sodium ion.
• Disodium Citrate ($Na₂HC₆H₅O₇$): Two hydrogen ions are replaced.
• Trisodium Citrate ($Na₃C₆H₅O₇$): All three hydrogen ions are replaced, making it the most common form.

Each type has a slightly different pH and taste, though trisodium citrate is the most widely used in the food and beverage industry.

What Sodium Citrate Is and Is Not

It's important to understand what sodium citrate is in relation to its source ingredient, citric acid, and its chemical nature as a salt.

Feature	Sodium Citrate	Citric Acid	Sodium Hydroxide	Sodium Bicarbonate
Chemical Nature	Salt	Weak Organic Acid	Strong Base	Weak Base
Appearance	White crystalline powder or granules	White crystalline powder	White solid/pellets	White powder
Taste	Mild saline, slightly tart	Strong sour/tart	Corrosive (DO NOT TASTE)	Saline, slightly bitter
Function	Emulsifier, buffer, preservative	Preservative, acidity regulator	Strong cleaning agent	Leavening agent (baking soda)
Use Case	Processed cheese, soft drinks	Jams, sodas, sour candies	Industrial cleaner, manufacturing	Baking, neutralization

Applications of Sodium Citrate Beyond Food

Beyond its well-known uses as a food additive, the composition of sodium citrate makes it valuable in several other industries due to its buffering and anticoagulant properties.

• Medical Field: Sodium citrate is used as an anticoagulant for stored blood during transfusions because it chelates (binds to) calcium ions, which are necessary for blood clotting. It is also used to treat metabolic acidosis by neutralizing excess acid in the blood and urine.
• Cosmetics and Personal Care: In personal care products like shampoos and moisturizers, sodium citrate acts as a buffering and chelating agent to stabilize formulations and maintain their shelf life.
• Detergents: Its ability to bind with metal ions makes it an effective water softener and cleaning agent, as it helps prevent the formation of hard water deposits.

Conclusion

In summary, the ingredients in sodium citrate are fundamentally simple: citric acid and a sodium-containing base, most commonly sodium hydroxide or sodium carbonate. The resulting salt, particularly the trisodium citrate form, is a white, crystalline powder prized for its functions as an emulsifier, preservative, and acidity regulator in a wide array of food, medical, and industrial applications. While the source of the citric acid can be natural (from fruit) or synthetic (from fermentation), the final chemical salt is produced through a controlled chemical reaction. This reliable and versatile compound is a testament to the power of a simple acid-base reaction.

References

• Abdul Sattar Sons. (n.d.). Food Grade Sodium Citrate, Buffering & Preserving Agent. https://abdulsattarsons.net/category/industrial-chemicals/product/sodium-citrate
• Green Llama. (n.d.). Sodium Citrate: A Comprehensive Overview. https://greenllamaclean.com/pages/sodium-citrate-a-comprehensive-overview
• Carbs Fuel. (n.d.). Sodium Citrate. https://carbsfuel.com/blogs/ingredients/sodium-citrate
• Shanghai Chemex. (2022, February 7). How to Neutralize Citric Acid?. https://shanghaichemex.com/how-to-neutralize-citric-acid/
• Vedantu. (2020, June 16). Sodium Citrate: Formula, Uses & Properties Explained. https://www.vedantu.com/chemistry/sodium-citrate
• Elchemy. (2025, April 12). Sodium Citrate Uses in the Food & Beverage Industry. https://elchemy.com/blogs/food-nutrition/sodium-citrate-uses-in-the-food-beverage-industry-a-functional-ingredient
• ChemicalBook. (2025, October 1). Sodium citrate | 68-04-2. https://www.chemicalbook.com/ChemicalProductProperty_EN_CB7360958.htm
• Wikipedia. (n.d.). Sodium citrate. https://en.wikipedia.org/wiki/Sodium_citrate
• Cleveland Clinic. (2025, February 27). Sodium Citrate & Citric Acid: Uses & Side Effects. https://my.clevelandclinic.org/health/drugs/20960-sodium-citrate-citric-acid-solution
• FoodAdditives.net. (2020, May 10). What is Sodium Citrate (E331) in food?. https://foodadditives.net/acidity-regulator/sodium-citrate/
• Study.com. (n.d.). What is the final product of citric acid combined with sodium hydroxide. https://homework.study.com/explanation/what-is-the-final-product-of-citric-acid-combined-with-sodium-hydroxide.html

Frequently Asked Questions

What is sodium citrate made from?

Sodium citrate is made from a simple acid-base neutralization reaction. The two main ingredients are citric acid, which is a weak organic acid, and a sodium-containing base, such as sodium hydroxide or sodium carbonate.

Is sodium citrate natural or artificial?

It can be both, depending on the source. The citric acid is often produced commercially through the fermentation of sugar by the fungus Aspergillus niger. However, the same salt can be created from naturally sourced citric acid found in citrus fruits.

What is the chemical formula for sodium citrate?

The most common form, trisodium citrate, has the chemical formula $Na₃C₆H₅O₇$. There are also monosodium and disodium forms, which have different formulas based on the degree of neutralization.

How is sodium citrate used in food?

In food, sodium citrate acts as an emulsifier, a preservative, and an acidity regulator. It is used in processed cheese to prevent fat separation, in beverages to balance tartness, and in jams to control gelling.

What is the difference between sodium citrate and citric acid?

Citric acid is a weak organic acid, while sodium citrate is the salt form created by neutralizing citric acid with a sodium base. Citric acid has a very sour taste, whereas sodium citrate has a milder, saline, and slightly tart flavor.

Why is sodium citrate used in medicine?

In medicine, sodium citrate is used as an anticoagulant for stored blood because it binds to calcium ions, which are essential for clotting. It is also used as an alkalinizing agent to reduce acidity in the body, which can help prevent kidney stones.

How does sodium citrate act as an emulsifier?

In products like processed cheese, sodium citrate's citrate ions bind with calcium, making the proteins more soluble and preventing the fats and liquids from separating. This results in a smooth, uniform texture.