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7720-78-7
Futurechemical
7720-78-7
project | information |
Chemical name | Ferrous sulfate |
Molecular formula | FeSO₄ |
CAS number | 7720-78-7 (Anhydrous food – Reference status in food regulations) |
molecular weight | 151.91 (anhydrous) |
Iron content | 36.8% (as Fe, theoretical value for anhydrous products); actual iron content in food-grade products varies depending on hydration level (~20%~33%). |
Appearance | Dry form: grayish-white to pale yellow powder; heptahydrate: blue-green crystals (this form is almost never used in food fortification). |
Solubility | It is extremely soluble in water (anhydrous solubility at 25°C ~40 g/100 mL) |
Advantages | Why it is important |
Highest bioavailability | It has the highest absorption rate among all oral iron sources—used as a reference for other iron sources (its relative bioavailability is defined as 100%). |
Lowest cost | The increased cost per ton of flour is negligible—the least financially burdensome public health intervention. |
Available globally | The titanium dioxide industry produces millions of tons of byproducts annually—food-grade FeSO₄ can be extracted from these industrial byproducts. |
However, its use is subject to certain conditions:
Limiting factors | Why not universally applicable? |
Short shelf life | The effective antioxidant protection period in flour is typically 2-4 weeks—suitable for fast-turnover mill-to-bakery supply chains, but not for remote areas or military rations that need to be stored for months. |
Not resistant to high temperature and high humidity | Under the high humidity storage conditions of tropical regions (Southeast Asia, Africa), FeSO₄ accelerates the oxidation of fats and the degradation of vitamins in flour. |
Incompatible with high phytic acid flour | Whole wheat flour and corn flour are high in phytic acid—phytic acid chelates Fe²⁺, making it unabsorbable. NaFeEDTA should be used instead. |
Color risk | Even in the dry form, a very slight dark gray tint may still be produced when it reacts with the phenolic compounds in flour at high concentrations. |
Iron fortification in infant formula and rice cereal is considered one of the "highest priority" micronutrient interventions in the global nutrition community. The period between 6 and 24 months is the golden window for brain development and also the period when iron deficiency is most likely to cause permanent damage.
Biscuits have extremely low water activity (Aw < 0.3). In this "molecular desert," the rate of oxidation is significantly suppressed—ferrous sulfate (even heptahydrate) can be safely added without rancidity or discoloration even after months of storage. This is one of the few food bases that can be used "naked" (without encapsulation) with ferrous sulfate.
Solution: Microencapsulated ferrous sulfate – FeSO₄ particles are completely coated with hydrogenated vegetable oil or ethyl cellulose, physically isolating iron and iodine in table salt. The capsule shell dissolves in the highly acidic environment of the stomach, allowing the two elements to be absorbed separately in the intestines.
DFS has been widely deployed in countries such as India, Nigeria, and Kenya, covering tens of millions of people.
Soy sauce and fish sauce: As a liquid iron fortification carrier for everyday condiments, NaFeEDTA is more common than FeSO₄ (it is more stable in sauces), but FeSO₄ is still an option;
Solid beverages and meal replacement powders: Dry form – stable in dry powder, dissolves colorlessly and tastelessly after reconstitution (microencapsulation).
Seasonings and soup bases: as carriers of hidden iron supplementation.
Summarize
The role of Ferrous Sulfate (CAS 7720-78-7) in food fortification can be summarized in one sentence:
It is the "benchmark" for all iron sources—its bioavailability is 100%, its price is the bottom line, and its global policy is the first choice.
Scene | What did it do? | What are the restrictions? |
Fortified flour | Each 100g provides 3-6mg of iron—protecting the iron nutrition of hundreds of millions of people at a cost of just a few cents. | Must be quickly turned over; must be stored in a dry place. |
Baby rice cereal | Iron is almost the sole source of nutrition after 6 months of age – iron protection during the irreversible window. | Microencapsulated blue dot protection is needed |
Double fortification of salt | Simultaneously addressing iron and iodine deficiency in a single carrier | Microencapsulation for physical isolation is necessary. |
It's not the mildest iron source (ferrous lactate is milder), not the most stable iron source (ferric pyrophosphate is more stable), and not the iron source with the highest iron content (elemental iron powder > 98%). But on the most realistic scale of human nutrition—"effective and inexpensive"—the white powder marked CAS 7720-78-7 remains the closest to the answer.
