Highly alkaline phosphates such as tetrasodium pyro and tripolyphosphate enhance protein's water-binding abilities. An increased water-holding capacity results in less moisture loss during cooking, and finished products with more tenderness and juiciness. In addition, alkaline phosphates improve binding in chopped and formed products by solubilizing actin and myosin proteins. Pyrophosphate and tripolyphosphate are best used for extracting soluble meat proteins for high-yield meats such as extended hams and turkeys. Adding sufficient salt (typically 1.5% to 2.0%) is important for achieving good yield during the phosphate extraction.
Polyphosphates inhibit warmed-over flavor and off-color caused by oxidation by sequestering or tying up iron and copper catalysts. Iron is present in meat as a component of the blood and muscle pigments hemoglobin and myoglobin, respectively, and copper is present in some seafood. These metals, released by cooking, accelerate flavor and color changes. Polyphosphates maintain fresh meat quality through extended storage by acting as metal-ion chelators.