The basics

According to the Free Online Dictionary, phosphate is salt or ester of phosphoric acid, which is any one of three chemical compounds made up of phosphorus, oxygen, and hydrogen. The two beneficial effects of phosphates in meat and poultry products are moisture retention and flavor protection. An example is the use of phosphates in the curing of ham where approved additives are sodium or potassium salts of tripolyphosphate, hexametaphosphate, acid pyrophosphate, or orthophosphates, declared as “phosphates” on labels.

USDA’s Food Safety and Inspection Service allowed the use of selected potassium phosphates and expanded use of all approved phosphates and sodium hydroxide in a wider range of poultry and red meat products in a 1982 ruling. The measure included, for the first time, the direct addition of phosphates during the processing of cooked sausages. Selected inorganic phosphates are approved for use in many whole-muscle and sausage products, at a level of addition of 0.05 percent, asserts Lynn Knipe, processed meats extension specialist at Ohio State University.

The nomenclature applied to phosphates can be quite confusing as a particular phosphate may be described by several different names, Knipe reports (see chart).

“Phosphates are quite different from other ingredients conventionally added to meat products,” Knipe adds. “There are 11 different phosphates, which have been approved for use in meat products and each one is somewhat different from the rest in its functional properties in meat.”

Meat of the matter

Noting that the way phosphates act in meat can be explained in several ways, Knipe identifies the chemical’s water-holding capacity (WHC) of post-rigor muscle as a key benefit. The substance increases the pH of the muscle, which increases its net negative charges.

“These negative charges increase the electrostatic repulsion between fibers and ultimately increases the hydration of the muscle,” Knipe explains. “Most of the food-grade phosphates raise the pH of meat, yet the relationship between their effect on pH and WHC varies with the different phosphates.”

The result, Knipe continues, is that alkaline phosphates are very forgiving in relation to cooking loss in meat products. They will enhance the stability of emulsion products and improve the binding of meat chunks in sectioned and formed meat products. Phosphates also protect emulsion products from variations in emulsifying and cooking temperatures, and would be extremely valuable in the production of low-sodium meat products.

The emulsion stabilizing action of alkaline phosphates is due to a number of functional properties of phosphates. Alkaline phosphates raise the pH of meat products. These phosphates exhibit a high pH in water, but since meat is a buffer itself, phosphates’ effect on meat pH is considerably less than in water.

“Even the limited increase in pH (approximately 0.6 unit maximum) increases WHC and protein solubility,” Knipe says. “On the negative side, this increase on pH will reduce the rate of cured color development.”

The other side

The use of phosphates in comminuted meat products is not without some problems, notes Knipe explaining that the addition of phosphates such as tripoly- and pyrophosphates reduce cured color development. “The cured color of phosphate-treated meat can be improved by adding the phosphate later in the chopping process or by holding the product 30-60 minutes prior to cooking,” he advises.

Another potential problem may be the combination of phosphates with high collagen meat. “It appears as though the addition of salt and phosphates to high collagen meat reduces the emulsion stability to a level below that of high collagen meat treated with salt alone,” Knipe reports.

Henk Hoogenkamp, food scientist, author and lecturer, says sodium acid pyro phosphate (SAPP) is another useful substance in meat and poultry processing.

“Over the course of a great many years the inclusion level of lean meat in sausage and hot dogs have declined,” notes Hoogenkamp, who has developed a range of functional ingredients based on dairy and vegetable protein. “Increasing quantities of mechanically deboned meat and soy protein have also contributed to the decline in the meat flavors consumers prefer. Significantly higher levels of soy protein concentrate or soy protein isolate in combination with mechanically deboned chicken does increase pH and subsequently reduce meat flavor. To offset this, it is helpful to somewhat reduce the pH by adding 0.2 percent SAPP.”

Higher pH levels also give lighter curing colors especially when soy protein isolate is used, Hoogenkamp concludes, pointing out that this can be offset by adding ‘red color’ and slightly increasing salt and spices.

Inorganic Phosphates Approved by USDA FSIS for Use in Meat Products

NaH2PO4

• MSP

• Monosodium dihydrogen

crthophosphate

• Sodium phosphate monobasic

• Sodium biphosphate

Tetrasodium pyrophosphate

Na4P2O7

• TSPP

• Sodium pyrophosphate

• Tetrasodium diphosphate

• Sodium diphosphate

Sodium hexametaphosphate

(NaPO3)13

• HMP

• Sodium polyphosphate

• Graham’s salt

Monopotassium phosphate

KH2PO4

• MKP

• Potassium dihydrogen

orthophosphate

• Potassium phosphate monobasic

Tetrapotassium pyrophosphate

K4P2O7

• TKPP

• Potassium pyrophosphate

• Tetropotassium diphosphate

Disodium phosphate

Na2HPO4

• DSP

• Disodium monohydrogen

orthophosphate

• Sodium phosphate dibasic

Sodium Tripolyphosphate

Na5P3O10

• STPP, STP

• Pentasodium tripolyphosphate

• Sodium triphosphate

Sodium acid pyrophosphate

Na2H2P2O7

• SAPP

• Disodium dihydrogen

pyrophosphate

• Acid sodium pyrophosphate

Dipotassium phosphate

K2HPO4

• DKP

• Dipotassium monohydrogen

orthophosphate

• Potassium phosphate dibasic

Potassium tripolyphosphate

K5P3O10

• KTPP

• Pentapotassium triphosphate

Source: Lynn Knipe, associate professor, meat science, Ohio State University