Application of Phosphate in Food Processing

There are two main functions of phosphate in food processing: one is as a quality improver to improve the structure and taste of food; the other is to be used as a mineral nutrition fortifier.

The role of phosphates in food processing is mainly based on the following properties of phosphates:

1. Buffering effect: The pH value of phosphate ranges from moderately acidic (PH~4) to strongly alkaline (PH~12). When different phosphates are matched in different proportions, the pH value can be stabilized at PH4.5 - Different levels of buffer between 11.7. In the pH range of most foods (PH3.5-7.5), phosphates can be used as efficient pH regulators and pH stabilizers, making food more delicious. The strongest buffering effect is orthophosphate, and for polyphosphate, the buffering capacity will decrease as the chain length increases.

2. Water-holding effect: Polyphosphate is a highly hydrophilic water-retaining agent, which can well stabilize the water contained in food. The quality of its water holding capacity is related to the type of polyphosphate, the amount of addition, the pH value of the food, the ionic strength and other factors. For meat products and seafood, the best water-holding capacity is pyrophosphate, followed by tripolyphosphate. As the chain length increases, the water-holding capacity of polyphosphate will weaken.

3. Polyanionic effect: Polyphosphate is a polymeric dielectric and has the characteristics of inorganic surfactants, which can disperse insoluble substances in water or form a stable suspension to prevent the suspension from attaching and coagulating. Polyphosphates are widely used in the phosphorylation of starch, the dispersion of pigments, and the emulsification of food (emulsion) because the hydrosol of the protein can form a film on the fat globule, so that the fat can be dispersed in the water more effectively. products, ice cream, salads, sauces, etc.) and as a dispersion stabilizer for sausages, minced meat products, and surimi products. For linear polyphosphates, its emulsifying and dispersing ability increases with the increase of chain length.

4. Chelation: Polyphosphate is easy to form soluble complexes with metal cations in the solution, thereby reducing the hardness of water and inhibiting the oxidation, catalysis, discoloration and decomposition of vitamin C caused by metal cations such as Cu2+ and Fe3+. Prevent and delay fat oxidation, prevent meat, poultry, fish spoilage, maintain color and prolong the shelf life of food. The chelation of polyphosphates depends on chain length and pH. Generally speaking, long-chain polyphosphates have strong chelating ability for light metal ions, which increases with the increase of pH value; short-chain polyphosphates have strong chelating ability for heavy metal ions, but with the increase of pH value increased, chelation weakened.

5. Protein effect: Phosphate has a strengthening effect on protein and prion, so it can improve the hydration and water holding capacity of meat products, improve the permeability of water, promote the softening of food, improve the quality of food, and maintain the flavor of food. At the same time, phosphate in dairy products can prevent the coagulation of milk when heated, and prevent the separation of casein and fat moisture.

6. Leavening effect: Acidic phosphates (such as sodium acid pyrophosphate, calcium hydrogen phosphate) are usually used as the leavening acid of the leavening agent for baked products, and react with bicarbonate to provide the carbon dioxide gas required for the baking process.

7. Anti-caking effect: Tricalcium phosphate is commonly used as an anti-caking agent to improve the free-flowing properties of powdered or hygroscopic foods. Tricalcium phosphate has a large specific surface area and can bind more water; and its special spherical crystal structure can produce a "ball effect", so that the powder has good free-flowing properties.

8. Extend the shelf life of food: Polyphosphate can enhance the storage stability of food and prolong the shelf life of the product. This effect is mainly based on: (1) PH regulating effect; (2) bacteriostatic effect: microbial cell growth must depend on divalent metal cations, especially Ca2+ and Mg2+, and phosphate can chelate with these metal cations, and it It can reduce the stability of the cell wall during cell division, and also reduce the thermal stability of many cells, thereby effectively inhibiting bacterial growth. The antibacterial effect of polyphosphate is related to its type (chain length), content, pH value, salt content, nitrite content and other factors. In general, as the chain length increases, the bacteriostatic effect increases.

9. Mineral nutrition enhancement: Calcium phosphate, magnesium phosphate, iron phosphate, and zinc phosphate are often used as mineral enhancers in food processing. Adding iron phosphate and zinc phosphate to gastric juice can enhance the biopharmaceutical effect of gastric juice because of its better solubility, and will not promote the occurrence of natural oxidation.