Sodium tripolyphosphate (STPP), the sodium salt of the polyphosphate penta-anion, also known as pentasodium tripolyphosphate or sodium triphosphate (different with trisodium phosphate), is a synthetic ingredient mainly used for retaining moisture in fish.

The European food additive number for it is E451(i).

Both food and tech grade available.

In the food industry, widely used for lunch meat, cooked ham, canned meat and other meat products, such as water retention agents, instant noodle rehydration agents.

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.