Pentasodium triphosphate is the sodium salt of triphosphoric acid, designated E450, one of the most widely used polyphosphate additives in food processing. It functions as an emulsifier, stabiliser, sequestrant, and water-retention agent: in processed meats and poultry it raises pH and opens protein structures so they bind more water, improving yield and juiciness; in processed cheese it emulsifies fat and protein into a smooth melt; in seafood it reduces drip loss on thawing. The compound illustrates phosphates’ versatility across the processed food sector. Regulatory limits cap its use, and labels must declare it, which matters to consumers monitoring phosphate intake. Excessive phosphate consumption is discussed in connection with cardiovascular and bone effects in vulnerable groups, though evidence at typical intakes supports the safety of authorised uses.