Food Grade90-95%、98% Industrial grade90-95%、98%,Sodium polyacrylate CAS 9003-04-7

What is sodium polyacrylate? How does it work? What are the food-grade applications of it?

1. What is sodium polyacrylate? How does it work?

Sodium polyacrylate, also known as sodium polyacrylate, is a high molecular weight polymer of sodium acrylate, with the chemical formula (C3H3NaO2)n and CAS number 9003-04-7. It is a white powder that dissolves in water to form a highly viscous, transparent solution. It is a food thickener approved for use, serving as a gluten enhancer, water retainer, thickener, and gelling agent in noodle products, meat products, sauces, beverages, and frozen foods—this is its core role in the food industry.

Basic information : Chinese name: Sodium polyacrylate; English name: Sodium polyacrylate (abbreviation: PAAS); CAS number: 9003-04-7; Molecular formula: (C3H3NaO2)n (repeating unit: sodium acrylate); Molecular weight: thousands to millions (depending on degree of polymerization); Appearance: white powder, soluble in water to form a highly viscous liquid, aqueous solution pH: 6-9; Synonyms: Sodium 2-acrylate homopolymer, sodium polyacrylate, PAAS, etc.

Structurally , sodium polyacrylate is a linear polymer formed by the polymerization of sodium acrylate monomers: the main chain is a long chain connected by carbon-carbon single bonds, and each repeating unit has a sodium carboxylate group (-COONa) attached to its side, with the structural unit being -CH2-CH(COONa)-. The sodium carboxylate group ionizes in water to release sodium ions, giving the molecular chain a large amount of negative charge. The repulsion of like charges causes the chain segments to fully extend, resulting in an extended conformation of the molecular chain. The molecular weight ranges from several thousand to several million; the higher the molecular weight, the stronger the thickening and water-retaining capacity.

Physically , sodium polyacrylate is a white powder or granules, odorless and tasteless, with strong hygroscopicity; it slowly dissolves in water to form an extremely viscous, transparent liquid, with a 0.5% solution having a viscosity approximately 15-20 times that of sodium carboxymethyl cellulose or sodium alginate; it is insoluble in organic solvents such as ethanol; its density is approximately 1.32 g/cm³; it is heat-resistant, and does not decompose even when heated to approximately 300℃; its viscosity changes very little over long-term storage, and it is not easily spoiled.

Chemically , sodium polyacrylate is an anionic polyelectrolyte: when dissolved in water, it ionizes into sodium ions and polyacrylate anions, and the molecular chain carries a large number of negative charges; it is easily affected by acids and metal ions—it can form insoluble salts and undergo cross-linking and gelation when it encounters divalent or higher metal ions (such as calcium, magnesium, aluminum, and zinc); heating, neutral salts, and organic acids have little effect on its viscosity, while viscosity increases under alkaline conditions; it is chemically stable, does not easily spoil or deteriorate, and needs to be stored in a moisture-proof environment.

Why does sodium polyacrylate have these functions in food products like flour products, meat products, sauces and beverages? The mechanism of action mainly involves the following:

Mechanism of thickening of anionic polyelectrolytes: The molecular chain contains a high amount of sodium carboxylate groups. When ionized , the negative charges repel each other , and the chain segments can spread out completely , occupying more space . This can be observed macroscopically as a large increase of the viscosity of the solution, the viscosity of a 0.5% solution being 15-20 times that of sodium carboxymethyl cellulose or sodium alginate. It is the heart of its high efficiency thickener.

Protein adhesion enhancement mechanism: Sodium polyacrylate reacts with the proteins in the flour to improve the adhesion of the protein network, making the dough more compact and extensible, increasing the elasticity of noodles and reducing the likelihood of dumpling wrappers breaking.

Starch network binding mechanism: It is able to bind starch particles and disperse into the protein network structure to form a stable dough colloid, prevent soluble starch from leaking, and improve the taste and appearance of dough products.

Strong water retention mechanism: Abundant hydrophilic groups in the molecular chain evenly retain water in the food matrix, prevent the product from drying out, reduce the occurrence of freezing cracks, and reduce the oil absorption rate in fried food processing, saving oil.

Electrolyte gelation mechanism: as an electrolyte, it interacts with proteins, changes protein structure and improves the viscoelasticity of food; it can crosslink and gel when it meets divalent metal ions, and plays a role in gelation and preservation in minced meat and fish products.

II. All uses of food-grade sodium polyacrylate

1. Flour Products Sector

Noodles and rice noodles

Improve the texture of raw noodles, dried noodles, and fried noodles, making them more chewy and smooth; reduce the oil absorption rate during the processing of fried foods such as instant noodles.

Corresponding products: dried noodles, instant noodles, rice noodles, dried noodles, etc.

flour products

It enhances the adhesiveness of proteins in flour, making the dough more extensible, improving moisture retention, reducing freezing cracks, and improving the taste of bread and cakes.

Corresponding products: bread, cakes, dumpling wrappers, glutinous rice balls, steamed buns, etc.

vermicelli, rice noodles, rice sheets

When using starches from sweet potatoes, corn, oats, potatoes, etc. as raw materials, the product's gluten content is increased and its resistance to boiling is enhanced.

Corresponding products: vermicelli, rice noodles, rice sheets, etc.

2. Meat and aquatic product sector

Meatballs, fish balls and ham sausage

Adding the right amount will enhance the flavor and make the product more chewy and tender.

Corresponding products: meatballs, fish balls, ham sausages, etc.

Fish paste products and canned goods

As a surface gelling agent, it strengthens the texture, maintains freshness, and enhances flavor.

Corresponding products: surimi products, canned meat, canned seafood, etc.

Frozen foods and processed seafood

It acts as a surface gelling agent to preserve freshness and reduce moisture loss during the freezing process.

Corresponding products: frozen aquatic products, frozen prepared foods, etc.

3. Condiments and Sauces

Sauces and gravy

It is used as a thickener and stabilizer in sauces, ketchup, mayonnaise, jam, cream, soy sauce, etc., to improve texture and cling to the sides of the container.

Corresponding products: sauces, ketchup, mayonnaise, jams, soy sauce, etc.

4. Beverages and Confectionery

Fruit juice and alcoholic beverages

It acts as a dispersant to ensure that the fruit pulp particles and alcohol components are evenly dispersed, thus maintaining the stability of the system.

Corresponding products: fruit juice, fruit-flavored beverages, alcoholic beverages, etc.

Ice cream and caramel candy

It improves flavor and stability, slows down the coarsening of ice crystals, and maintains a delicate texture.

Corresponding products: ice cream, caramel, candy, etc.

Clarification of sugar solution and beverage

It is used as a clarifying agent (polymer coagulant) for the clarification of sugar solutions, brine, and beverages.

Corresponding products: sugar solution, beverages, salt water, etc.

III . Summary

Sodium polyacrylate (CAS 9003-04-7) is a linear polymer of sodium acrylate. The densely packed sodium carboxylate groups on its main chain ionize in water, allowing the chain segments to fully extend, making it a highly efficient food thickener with a thickening efficiency 15-20 times that of sodium carboxymethyl cellulose and sodium alginate. It makes noodles more chewy, dumpling wrappers more resistant to overcooking, meatballs more tender, sauces thicker, and frozen foods retain more moisture—protecting readily available processed foods in our daily meals with extremely low dosage. Understanding its polyelectrolyte structure and high-viscosity solution explains its enduring popularity in the processing of noodle products, meat products, sauces, and beverages.