There are many different polyphosphates with widely varying properties. To achieve the most effective additive for each use, the manufacturers produce combinations of polyphosphates that are tailored to the various foods.
Polyphosphate has been used in food since 1950. Polyphosphates are used for many purposes: in meat products, they are used to improve binding properties, to reduce moisture loss in cooking and thawing - and thereby reduce wastage - and to prevent the products becoming dry. This occurs for example with meat sandwich fillings that are cooked at a high temperature or in frozen chicken, which easily loses fluid when thawing. Polyphosphates also reduce rancidity and improve the appearance of meat products in the freezer cabinet. Polyphosphates also extend shelf life through their positive effect on chemical and microbiological deterioration.
Polyphosphates are safe additives in the concentrations used in food. There has been some speculation that polyphosphates can sequester minerals and prevent the body taking up calcium, for example. But a number of studies have shown that in practice polyphosphate has no effect on the take up of minerals in the intestine. We may add that various kinds of phosphates are found naturally in the body and are in fact essential.
Limits have been set for the amount that is permitted in different products. In the EU, the quantities have been set by the directive on food additives. The upper limit for polyphosphates in meat has been set at 0.5% in the finished product. Normal usage in meat products is 0.2-0.3%, or about half of what is permitted. If too much polyphosphate is added, the food gets a soapy aftertaste. In Norway, polyphosphates have been used in sandwich filling products for many years and they have also been permitted in meat pastes and stuffings since 1999.