What is Sodium Tripolyphosphate (E451i)? Uses, Safe, Side effects

What is Sodium Tripolyphosphate (E451i)? Uses, Safe, Side effects


Table of Contents

Sodium tripolyphosphate (Na5P3O10) is a salt of phosphate ester and sodium, with the chemical formula Na5P3O10. The sodium salt of tripolyphosphate (STPP), one of the most important water-soluble polyphosphate compounds, is often used in detergents as builders to soften hard water, prevent the formation of limescale on household appliances, and improve both the whiteness and brightness of fabrics. (1)

What is sodium tripolyphosphate?

Sodium tripolyphosphate (STPP) is a sodium salt of tripolyphosphoric acid. It is a water-soluble, crystalline powder that is used as a food additive, pharmaceutical ingredient, and flame retardant.

STPP is produced by combining phosphoric acid with sodium hydroxide and carbon dioxide. The resulting precipitate is filtered, washed, and dried to produce the white powder.

STPP’s chemical formula is Na5[(PO3)4] or 3Na(PO4)2·8H2O. It contains sodium ions, phosphorus ions, and oxygen atoms in various proportions according to its source material. (2)

What is sodium tripolyphosphate used for?

What is maltodextrin

Sodium tripolyphosphate is used in foods as a preservative to keep them looking fresh.

It’s also used in the pharmaceutical industry as a thickening agent and buffer.

Sodium tripolyphosphate is also added to cleaning agents, laundry detergents, dishwashing liquids, and toothpaste. It may be used in personal care products such as toothpaste, hand soap, and mouthwash as an anti-irritant or mild abrasive agent.

In cheese making, sodium tripolyphosphate helps control moisture loss and prevents unwanted odors such as ammonia from developing during ripening.

Sodium tripolyphosphate may be used to increase the viscosity (thickness) of drilling fluids used in the oil industry.

Why is sodium tripolyphosphate used in food?

Sodium Tripolyphosphate (STPP) is used in the food industry as a leavening agent or dough conditioner. It can also be used as a buffering agent, emulsifier, and stabilizer. The Food and Drug Administration (FDA) has approved sodium tripolyphosphate for use in commercial food products.

Food manufacturers add sodium tripolyphosphate to foods such as baked goods, beverages, candy, and other snacks to enhance their texture, color, and flavor. The salt also helps to keep these items moist during storage.

Sodium tripolyphosphate is approved by the FDA as an indirect food additive that acts as an anti-caking agent, anti-foaming agent, firming agent, preservative agent, sequestrant and thickener in foods such as cheese spread; sausage casings; ice cream mix; frozen yogurt mix; powdered drink mixes; non-dairy creamers; peanut butter; salad dressing mixes; salad oils; mayonnaise dressings.

How is sodium tripolyphosphate made?

In sodium tripolyphosphate, three simple phosphate units are linked together to form a polyphosphate.

Here are the brief manufacturing processes:

  1. A mixture of monosodium phosphate and disodium phosphate is produced by neutralizing phosphoric acid with sodium hydroxide.
  2. After that, heat the mixture to 500-550°C. This is the reaction equation: NaH2PO4 + 2Na2HPO4 → Na5P3O10 + 2H2O

There are two types of food grade STPP, each with its own chemical formula:

  1. STPP Anhydrous: Na5O10P3
  2. STPP Hexahydrate: Na5O10P3 · 6H2O


Other names
  • Pentasodium tripolyphosphate
  • Sodium triphosphate
CAS number7758-29-4
AppearanceWhite powder or granular powder
SolubilitySoluble in water, insoluble in ethanol
PH9.1 to 10.2 (1 % solution)


Sodium tripolyphosphate structure

What is the application of sodium tripolyphosphate?

The primary use of food-grade sodium tripolyphosphate is to improve the eating quality of food products, particularly meat and fish. Additionally, it is used in pet food to keep the animal feed fresh and to bind water.

Additionally, it can be used to modify food starch.

The technical grade STPP is widely used in the production of laundry detergents and dishwashing detergents, industrial water softeners, industrial cleaners, grease removers, leather pre-tanning agents, dyeing auxiliary agents, and so on.

Here are its detailed uses in fish and meat.


The primary purpose of STPP is to reduce the amount of thaw water (or maintain water) and make seafood look more firm and smooth. It is often added to fish (e.g. salmon) before freezing. As well as scallops, shrimp, and lobster, which you may also find in frozen seafood.

Most seafood is easily damaged by ice crystals and protein denaturation during freezing storage, which damage taste, odor, texture, and juiciness.

Fish meat’s water retention performance is determined by its protein content. During freezing, polyphosphate prevents protein denaturation by retaining water.

A solution of sodium tripolyphosphate at a certain concentration is used in the production of frozen fish fillets.

A fish’s ability to retain water is closely related to its texture, tenderness, sliceability, elasticity, and taste. Without sodium tripolyphosphate, most seafood loses weight (water), turns darker, and becomes fragile when thawed.


The main purposes of phosphate in meat processing are as follows:

  1. Juiciness, tenderness, and water retention
  2. Reducing the rate of oxidative spoilage
  3. Maintaining color and flavor

Sodium polyphosphate, sodium pyrophosphate, and sodium hexametaphosphate are some of the phosphates commonly used and produced in the meat industry.

In the meat processing industry, polyphosphates are commonly used as additives. In addition to improving texture and color, STPP reduces cooking loss and increases product yield. Increasing pH, strengthening ionic power, and chelating metal ions are believed to be the mechanisms.

In meat, STPP interacts with amino acids or hydroxyl groups to improve water retention and gel strength.

Furthermore, combining it with sodium chloride can reduce meat’s sodium content compared with just using sodium chloride alone. Sodium tripolyphosphate (anhydrous) contains only 31.3% sodium, whereas NaCl contains 39.3% sodium.

Is sodium tripolyphosphate safe to use?

Sodium tripolyphosphate is a food additive that helps control acidity in foods. It’s also used as an emulsifier and stabilizer in many products, including baked goods, cheese spreads, canned meats, frozen desserts, and processed meats.

It’s considered to be generally safe by the Food and Drug Administration (FDA), but some people may be allergic to the ingredient or experience side effects from eating too much of it.

The FDA classifies sodium tripolyphosphate as “generally recognized as safe” (GRAS), meaning there is no evidence that supports its toxicity at low doses (less than 1 gram per day). However, you should avoid consuming more than 1 gram per day because it can cause side effects such as bloating, gas, diarrhea, and abdominal cramping when consumed in excess of this amount.

What is sodium tripolyphosphate used in water treatment?

Sodium tripolyphosphate is used in water treatment to remove phosphates from water. It is also known as STPP, which stands for sodium tripolyphosphate. This chemical is a white powder that is made up of sodium, phosphorus, and oxygen. It can be used to treat drinking water, wastewater, and industrial waste.

Sodium tripolyphosphate works by binding with phosphate ions in the water, which are responsible for causing eutrophication in water bodies. Eutrophication occurs when too many nutrients enter a body of water and cause excessive growth of algae and weeds. This process can lead to dead zones where no aquatic life can survive due to the lack of oxygen caused by the decomposition of organic matter by bacteria.

When STPP binds with phosphate ions, they form insoluble complexes, which settle out at the bottom of ponds or lakes where they cannot harm wildlife living there or affect the ecology of those bodies of water.

Sodium tripolyphosphate vs Trisodium phosphate

Sodium tripolyphosphate and trisodium phosphate are two types of sodium phosphates that are used as cleaning agents. Both these chemicals work by binding to the surface of dirt, grease and other contaminants. They then lift them off surfaces so they can be rinsed away.

Sodium tripolyphosphate (STPP) is a white powder that is used as a water softener. It is made by reacting phosphorus pentoxide with sodium hydroxide to form sodium salt. The reaction produces phosphoric acid that is neutralized by adding base to it. STPP is an effective cleaner of hard water because it attracts the calcium and magnesium ions present in the water and forms insoluble compounds with them. The hardness of the water decreases and its pH level increases due to this process.

Trisodium phosphate (TSP) is also known as trisodium orthophosphate or TSP-14. It is a white granular or powdery substance with a salty taste and chemical formula Na3PO4(OH)2. It dissolves easily in water, forming an alkaline solution. This solution has a cleaning action on surfaces such as concrete floors, paintwork and metal surfaces when it comes in contact with them for some time.

What does sodium phosphate do to your body?

Sodium phosphate is a type of salt that’s common in processed foods. It can be used as a preservative, an emulsifier, and a thickening agent. Sodium phosphate is also used in many prescription drugs, including over-the-counter medications like antacids and laxatives.

Your body needs some sodium to function properly. Sodium helps regulate your blood pressure and keeps you from getting dehydrated. Your kidneys regulate how much sodium is in your blood by removing excess amounts of it through urination. If you eat too much sodium, your kidneys aren’t able to keep up with all the excess fluids, resulting in water retention and bloating — especially around your face and hands.

If you have high blood pressure or kidney disease, sodium phosphate may increase your risk of heart attack or stroke because it increases the amount of fluid circulating throughout your body. High sodium intake may also increase your risk of diabetes because it causes insulin resistance (when cells lose their ability to respond to insulin).

If you’re taking a prescription drug containing sodium phosphate, talk with your doctor about how much sodium is safe for you to consume each day based on your medical history

What are the side effects of sodium tripolyphosphate?

Sodium tripolyphosphate is a safe chemical to use in food and drink. However, it can cause mild side effects such as diarrhea and nausea.

The most common side effects of sodium tripolyphosphate include:

Allergic reactions. Hypersensitivity reactions occur when you take an allergy medication with sodium tripolyphosphate. These reactions are rare but can be serious, causing hives and difficulty breathing (asthma). If you have any type of allergic reaction, stop taking this medicine and call your doctor immediately.

Gastrointestinal distress. Taking too much sodium tripolyphosphate can cause nausea, vomiting and diarrhea.

Low blood pressure (hypotension). This side effect can occur if you take too much sodium tripolyphosphate in combination with other medications that lower your blood pressure (antihypertensives). If you feel dizzy or lightheaded while taking this medicine or after stopping it, contact your doctor right away because it could be a sign of low blood pressure that needs treatment.

Where to buy sodium tripolyphosphate?

You can buy sodium tripolyphosphate from online retailers like Amazon and eBay, or from industrial chemical suppliers such as Sigma-Aldrich.

You should also be able to find it in the form of a solid powder at your local drugstore or grocery store.

If you want to buy a good price for sodium tripolyphosphate, you can consider purchasing from Grade Chemical. Which is one reliable food additives supplier in China. they can supply you much more competitive price than the local market price.

Frequently Asked Questions:

Is sodium tripolyphosphate natural?

Sodium tripolyphosphate is not a natural product. It is a synthetic chemical that has been created by humans. However, it is used in many products that are natural, such as detergents or toothpaste.

Is sodium tripolyphosphate vegan?

Sodium tripolyphosphate is a non-animal derivative, which means that it doesn’t come from animal products, such as bones or blood. As such, it’s vegan-friendly!

Is sodium tripolyphosphate halal?

According to the Islamic Food and Nutrition Council of America, sodium tripolyphosphate is not halal. The IFANCA states that “sodium tripolyphosphate (STPP) is not considered Halal because it is made from pork fat or pork by-products.”

Is sodium tripolyphosphate harmful?

No, sodium tripolyphosphate is not harmful.

Sodium tripolyphosphate is a chemical compound used to make laundry detergents, dishwashing liquids, and glass cleaners. It is made from phosphoric acid and sodium hydroxide. It can also be used as a food additive to add texture to processed cheese.

Sodium tripolyphosphate is non-toxic and safe for use in household products. It is also considered environmentally friendly because it breaks down easily.


The above information helps us to understand the health benefits and side effects of tripolyphosphate or sodium tripolyphosphate. In fact, there are various benefits of tripolyphosphate but in large quantities, it can cause some complications. For example, high blood pressure, frequent urination, and nausea. So remember to follow the prescribed dosage from your doctor.

if you have any questions or comments want to share with us, please leave them in the below comments

Sophie Feng

Sophie Feng

Sophie Feng is the author of gradechemical.com, she is the co-founder of the grade chemical network. She has been in grade chemical company since 2017, with a working knowledge of food chemical .

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