Sodium phosphates

E339, commonly known as sodium phosphates, refers to a group of compounds derived from a combination of sodium and phosphate ions. These compounds include sodium hydrogen phosphate (Na₂HPO₄), sodium orthophosphate (Na₃PO₄) and sodium dihydrogen phosphate (NaH₂PO₄). They are white, crystalline powders that are highly soluble in water and have a variety of applications due to their buffering, emulsifying and sequestering properties.

Origin

Sodium phosphates can be of both natural and artificial origin. They are generally produced by neutralising phosphoric acid with sodium hydroxide or sodium carbonate. This process leads to different types of sodium phosphates depending on the ratios used and the specific conditions.

Characteristics and uses in the food industry

Sodium phosphates are used in food processing for several reasons:

• Buffering agent: It maintains the pH level of food, preventing it from becoming too acidic or alkaline.
• Emulsifying agent: Helps in mixing and stabilizing oil and water mixtures.
• Sequestering agent: Binds metal ions, preventing their catalytic oxidation of fats.
• Loosening agent: Aids the leavening of baked goods by releasing carbon dioxide.
• Texturizing agent: Improves texture and moisture retention in food.

Use in ultra‑processed foods

In ultra‑processed foods, sodium phosphates perform various important functions:

• Processed Meat: Sodium phosphates are used to retain moisture, improve texture and enhance flavor in processed meats such as sausages, hams and deli meats. They help bind meat proteins, improving overall juiciness and tenderness.
• Dairy: in cheese making, sodium phosphates act as emulsifiers, ensuring a smooth and homogeneous product. They prevent the separation of fat and water, resulting in a consistent texture and appearance.
• Bakery products: in baking, sodium phosphates act as leavening agents, reacting with baking soda to release carbon dioxide, helping the dough to rise and achieve a light and fluffy texture.
• Beverages: in beverages, especially those high in protein or calcium, sodium phosphates act as stabilizers to prevent precipitation and ensure even distribution of ingredients.
• Ready meals: Sodium phosphates are used in ready meals and snacks to improve texture, extend shelf life and maintain colour and flavour.

Health effects

Although sodium phosphates are generally considered safe (GRAS) when used in accordance with good manufacturing practices, there are potential health aspects associated with their consumption:

• Phosphate load: Excessive phosphate intake can disrupt the body's calcium and phosphate balance, which can lead to bone demineralisation and an increased risk of osteoporosis.
• Kidney function: Individuals with impaired kidney function may have difficulty excreting excess phosphate, which can lead to hyperphosphatemia, which can cause vascular calcification and cardiovascular disease.
• Digestive disorders: High levels of sodium phosphate may cause digestive disorders in some individuals, including bloating, diarrhea and abdominal pain.
• Irritation and inflammation: Excessive intake of phosphate additives may contribute to inflammation of the intestines in some individuals, especially those with pre‑existing gastrointestinal problems. This could worsen symptoms of disorders such as irritable bowel syndrome (IBS).
• Microbiota imbalance: some studies suggest that high levels of dietary phosphate can alter the composition of the gut microbiota. This can potentially upset the balance between beneficial and harmful bacteria, leading to digestive problems and other health problems.
• Inflammatory reactions: some studies suggest that excessive phosphate consumption can lead to systemic inflammation, a risk factor for metabolic syndrome and other chronic diseases. The inflammatory reaction may result from changes in intestinal permeability caused by high phosphate intake.

Sources

1. Food and Drug Administration. (2021). Food Additive Status List. Retrieved from FDA.
2. EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS). (2019). Re‑evaluation of phosphoric acid‑phosphates‑di-, tri- and polyphosphates (E 338‑341, E 343, E 450‑452) as food additives. EFSA Journal, 17(6), e05674.
3. Institute of Medicine. (1997). Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. Washington, DC: The National Academies Press. doi:10,17226/5776.
4. Kalantar‑Zadeh, K., Gutekunst, L., Mehrotra, R., Kovesdy, C. P., Bross, R., Shinaberger, C. S.,... & Kopple, J. D. (2010). Understanding sources of dietary phosphorus in the treatment of patients with chronic kidney disease. Clinical Journal of the American Society of Nephrology, 5(3), 519‑530.
5. Rucker, R. B., & Biochemical Society. (2005). Phosphorus and health. The Journal of Nutrition, 135(3), 776‑779. doi:10,1093/jn/135.3.776.
6. Takeda E, Yamamoto H, Yamanaka‑Okumura H, Taketani Y. Dietary phosphorus in bone health and quality of life. Nutr Rev. 2012 Jun;70(6):311‑21. doi: 10,1111/j.1753‑4887,2012.00473.x. PMID: 22646125.