Ferric pyrophosphate is a commonly used food additive, mainly used for the nutritional fortification of foods. The following are the main factors affecting its stability in foods:
Temperature: Generally speaking, an increase in temperature will accelerate the decomposition reaction of ferric pyrophosphate and reduce its stability. For example, in high-temperature baked foods, when the temperature exceeds a certain range, it may undergo structural changes, leading to a change in the existing form of iron elements, which will affect its bioavailability and stability in foods.
pH value: The stability of ferric pyrophosphate varies in environments with different pH values. It is relatively unstable under acidic conditions and is prone to dissociation, releasing iron ions. However, in a neutral or weakly alkaline environment, ferric pyrophosphate has better stability. For instance, it can maintain good stability in a food system with a pH value of 6-8 and is not likely to undergo obvious degradation or deterioration.
Water activity: The water activity in foods has a significant impact on the stability of ferric pyrophosphate. High water activity will promote the hydrolysis reaction of ferric pyrophosphate and reduce its stability. For example, in wet foods with a high water content, it may interact with water molecules, resulting in the destruction of its structure. The iron ions are more likely to be oxidized or form other compounds, thus reducing its stability in foods.
Metal ions: The presence of other metal ions in foods may interact with ferric pyrophosphate and affect its stability. Some metal ions such as zinc ions and copper ions may undergo an exchange reaction with the iron ions in ferric pyrophosphate, or form more stable complexes with pyrophosphate ions, thereby changing its structure and properties and reducing its stability.
Antioxidants: Antioxidants added to foods can affect the stability of ferric pyrophosphate. Antioxidants can inhibit the oxidation reaction in foods and reduce the possibility of iron ions being oxidized, thus helping to maintain its stability. For example, antioxidants such as vitamin C can act synergistically with ferric pyrophosphate to prevent iron ions from being oxidized to a higher valence state and improve the stability of ferric pyrophosphate in foods.
Food components: Some components in foods, such as proteins, fats, and carbohydrates, can also affect the stability of ferric pyrophosphate. Proteins can form complexes with it, increasing its stability in foods; while the free radicals generated during the oxidation of fats may trigger the oxidative decomposition of ferric pyrophosphate, reducing its stability; carbohydrates may indirectly affect its stability by influencing the viscosity and water distribution of foods.
