Phosphates used in food processing are usually sodium salts, calcium salts, potassium salts, iron salts, and zinc salts as nutritional fortification agents. Sodium phosphate salt is currently the primary type of food phosphate consumption. With the development of food processing technology, the consumption of potassium phosphate salt is also rising year by year.
Phosphates have lots of Functions in food processing:
- Buffering effect
- Water-holding effect
- Chelation
- Protein role
- Bulking effect
- Anti-caking effect
- Extend food shelf life
- Mineral nutrient fortification
1. Buffering effect
The PH value of phosphate ranges from moderately acidic (PH~4) to strongly alkaline (PH~12), and when different phosphates are combined in different ratios, different levels of buffers can be obtained with PH stabilization between PH4.5 and 11.7. In the PH range of most foods (PH3.5-7.5), phosphates can be used as efficient PH regulators and PH stabilizers to make the food taste better. The strongest buffering effect is for orthophosphates, and for polyphosphates the buffering capacity decreases with increasing chain length.
2. Water-holding effect.
Polyphosphate is a very hydrophilic water retention agent, which can well stabilize the water contained in the food. The water-holding capacity is related to the type of polyphosphate, the amount added, 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, and with the increase of chain length, the water-holding capacity of polyphosphate will be weakened.
3. Polyanion effect
Phosphorylation treatment of starch, dispersion of pigments, emulsified foods (dairy products, ice cream, salads, sauces, etc.), and as a dispersion stabilizer for sausages, minced meat products, and surimi products.
4. Chelation
Prevent and delay fat oxidation, prevent meat, poultry, and fish from spoiling, and maintain color for the purpose of extending the shelf life of food.
5. Protein role
Phosphate has an enhancing effect on protein and gliadin, thus improving the hydration and water holding capacity of meat products, improving water permeability, promoting the softening of food and improving the quality of food, and maintaining the flavor of food. At the same time, phosphate in dairy products can prevent the coagulation of milk when heated, to prevent the separation of casein and fat water.
6. Bulking effect
Acidic phosphates (e.g., acidic sodium pyrophosphate, calcium hydrogen phosphate) are commonly used as bulking acids for baked goods bulking agents, and bicarbonate reacts to provide the carbon dioxide gas needed 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. It gives good free-flowing properties to powders.
8. Extend food shelf life
Polyphosphates enhance the storage stability of foods and extend the shelf life of products. This effect is mainly based on :
（1）PH regulating effect.
（2）Antibacterial effect.
9. Mineral nutrient fortification
Calcium phosphate, magnesium phosphate, iron phosphate, and zinc phosphate are often used as mineral enhancers in food processing. The addition of iron phosphate and zinc phosphate to gastric juice enhances the biopharmaceutical effect of gastric juice due to their better solubility and does not promote natural oxidation.
Phosphate safety issues
The safety of phosphate as a food additive is of great concern to people, many foreign scientists have conducted a large number of studies on the toxicology of phosphate, confirmed that food phosphates are non-toxic, safe additives.
The Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) Special Committee on the Safety of Phosphorus (P2O5) has evaluated the permissible daily intake for adults to be 1.4-1.5 g P2O5, while the 1985 Food Additives Committee recommended an unconditional acceptance level of <30 mg/kg body weight and a conditional acceptance level of 30 – 70 mg/kg body weight for total phosphorus in the diet.
It must be noted here that in the application of food phosphates, we should pay attention to the balance of calcium and phosphorus (calcium and phosphorus ratio of 1:1.2 is good), and the use of food additives in strict accordance with the provisions of health standards for the reasonable use of food phosphates, to avoid the occurrence of calcium and phosphorus imbalance or abuse of phosphates that lead to adverse effects on human health.
