Calcium pyrophosphate (CAS 35405-51-7, Ca2P2O7, MW 254.10) is a food-grade calcium phosphate salt supplied to Food Chemicals Codex (FCC) specification. It functions as a leavening acid, calcium fortifier, acidity regulator and mild abrasive, and is used in bakery, nutrition, oral care and industrial applications. This guide covers its chemistry, production, specifications and uses.
1. What Is Calcium Pyrophosphate?
Calcium pyrophosphate is the condensed (dehydrated) form of dicalcium phosphate: two phosphate units joined as a pyrophosphate (P2O7) group with two calcium ions. It is a white, tasteless, free-flowing powder, practically insoluble in water and stable at high temperature – properties that make it useful both as a food ingredient and as a polishing agent.
2. Chemistry and Properties
| Property | Value |
|---|---|
| Molecular formula | Ca2P2O7 |
| Molecular weight | 254.10 g/mol |
| Appearance | White, tasteless, free-flowing powder |
| Solubility | Practically insoluble in water; soluble in dilute acid |
| Assay (CaO basis) | 96% min as Ca2P2O7 |
| Loss on ignition (800 °C) | 1.00% max |
| Particle size | On 200 mesh 1% max; on 325 mesh 2% max |
3. Production Technology
- Neutralisation: phosphoric acid reacts with a calcium source (lime or calcium carbonate) to form dicalcium phosphate.
- Dehydration/calcination: dicalcium phosphate is calcined at high temperature to eliminate water and condense the phosphate groups into calcium pyrophosphate.
- Milling and grading: the product is milled and classified to the required mesh (e.g. 200/325 mesh for food and oral-care grades).
Purity control covers assay, loss on ignition, heavy metals, fluoride, arsenic and lead – the FCC specification items.
4. Specifications (FCC)
Assay 96% min (CaO basis as Ca2P2O7); loss on ignition (30 min/800 °C) 1.00% max; heavy metals (as Pb) 15 ppm max; fluoride 50 ppm max; arsenic 3 ppm max; lead 2 ppm max; residue on 200 mesh 1% max and on 325 mesh 2% max; white, tasteless, free-flowing powder; result according with FCC.
5. Applications Overview
- Bakery – leavening acid in baking powders and self-raising flours.
- Nutrition – calcium and phosphorus fortification of foods and supplements.
- Oral care – polishing/abrasive agent and anti-tartar component in toothpaste.
- Industrial – ceramics, glass, coatings and water-treatment applications.
6. Application Details
6.1 Leavening acid in bakery
As a slow-acting leavening acid, calcium pyrophosphate reacts with bicarbonate during mixing and baking, releasing CO2 in a controlled way. This gives good volume and crumb structure in cakes, biscuits and pancakes, with little after-taste – unlike faster-acting acids.
6.2 Calcium fortification
Both calcium and phosphorus are nutritionally valuable; the salt is used in fortified foods, meal-replacement products and supplements where a neutrally flavoured, insoluble calcium source is preferred.
6.3 Oral care
Its defined particle size and mild hardness make calcium pyrophosphate a polishing agent in toothpastes; it also contributes anti-tartar activity by being compatible with fluoride systems.
7. Comparison with Related Calcium Phosphates
| Product | Formula | Character | Typical use |
|---|---|---|---|
| Calcium pyrophosphate | Ca2P2O7 | Condensed, insoluble, slow-acting acid | Leavening, oral care, fortification |
| Dicalcium phosphate | CaHPO4 | Hydrated, mild acid | Leavening, calcium source, tablets |
| Tricalcium phosphate | Ca3(PO4)2 | Alkaline, insoluble | Anti-caking, calcium source |
| Mono/dicalcium blend | – | Fast-acting acid | Instant baking powders |
8. Buying Guide
- Specify FCC grade and confirm assay, loss on ignition, heavy metals, fluoride, arsenic and lead on the COA.
- Confirm particle size (200/325 mesh) for bakery, tablet or oral-care use.
- Request a food-grade certificate (FCC compliance statement) and packaging details (25 kg bags with PE liner).
9. Safety and Handling
- Food-grade material; avoid dust generation and use respiratory protection when handling bulk powder.
- Store sealed, cool and dry away from strong acids.
10. FAQ
Is calcium pyrophosphate suitable for baking powder?
Yes – it is a classic slow-acting leavening acid used in double-acting baking powders.
What does “according with FCC” mean?
The product meets the Food Chemicals Codex monograph requirements for food-grade calcium pyrophosphate, verified by the COA specification items listed above.
11. References and Further Reading
- PubChem entry for calcium pyrophosphate (CID 24632).
- Food Chemicals Codex (FCC) monograph, calcium pyrophosphate.
- Supplier COA and MSDS for the specific grade quoted.
This article is published for industrial and technical reference by PolyblueChem. Verify all values against the supplier’s COA and applicable food regulation before specification.
PolyblueChem supplies calcium pyrophosphate (CAS 35405-51-7) in FCC food grade with COA and MSDS. Contact us for specifications and quotations.