With the capability of maintaining water, the primary uses of food grade sodium tripolyphosphate are to improve the eating quality in food processing, especially in meat and fish products. It is also applied in pet food (e.g. cat and dog food) for the purpose of binding water and keeping the animal feed fresh.

It may also be used as a food starch modifier.

With the functions of chelating metal ions, suspending, dispersing, emulsifying, pH buffering, and etc, technical grade STPP is widely used in the production of laundry detergents & dishwashing detergents, industrial water softener, industrial cleaner, a grease remover, leather pre-tanning agent, dyeing auxiliary agent and so on.

Let’s see its detailed uses in fish and meat.

Fish
STPP is a common ingredient added to fish (e.g. salmon) before frozen and its primary purpose is to reduce the amount of thaw water (or maintain water) and make seafood look firmer and smoother. You may also find it in other frozen seafood, such as scallops, shrimp, and lobster.

The taste, odor, texture, and juiciness are important properties of seafood but most seafood is easily damaged caused by ice crystals and the protein denaturation during the freezing storage.

It is the protein in fish meat that determines the water retention performance. Polyphosphate is a widely used water-retaining agent for seafood to prevent protein denaturation during freezing.

In the production of frozen fish fillets, the fish fillets are soaked in a solution of sodium tripolyphosphate with a certain concentration before freezing.

The level of water retention performance is closely related to the quality of fish products such as texture, tenderness, sliceability, elasticity, and taste. If without sodium tripolyphosphate, when thawed, most seafood is prone to lose weight (water) and generate a darker appearance and as well make the body fragile.

Meat
Phosphate is widely used in meat processing and its main purposes are as follows:

Water retention, emulsification stability, juiciness and tenderness
Delaying the rate of oxidative spoilage
Improving color and maintaining flavor
The phosphates commonly used in meat production include sodium polyphosphate, sodium pyrophosphate and sodium hexametaphosphate.

Polyphosphates are commonly used additives in meat processing. The addition of STPP to meat improves texture & color, reduces cooking loss, and increases product yield. Such a mechanism is believed through increasing pH, strengthening ionic power, and chelating metal ions.

STPP interacts with amino acids or hydroxyl groups in proteins, thus improving the water retention and gel strength of meat.

Meanwhile, its combination with sodium chloride can reduce the sodium content in meat compared with using sodium chloride only. NaCl contains 39.3% sodium, while in sodium tripolyphosphate (anhydrous) the sodium content is only 31.3%.