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Views: 0 Author: Site Editor Publish Time: 2026-08-06 Origin: Site
Calcium phosphate monobasic — universally known in industry as monocalcium phosphate (MCP) — is an inorganic acid phosphate with the chemical formula Ca(H₂PO₄)₂. It typically occurs as the monohydrate (Ca(H₂PO₄)₂·H₂O, CAS 7758-23-8), though an anhydrous form (CAS 7758-23-8, identical CAS) also exists. In food regulatory systems, it carries the designation E341(i) .
MCP is the most acidic member of the calcium phosphate family — a property that defines its industrial identity. Unlike its neutral cousin dicalcium phosphate (DCP) or its alkaline sibling tricalcium phosphate (TCP), MCP dissolves readily in water and reacts rapidly with alkaline substances. This makes it the preferred fast-acting leavening acid in commercial baking and the highest-bioavailability phosphorus source in animal nutrition.
Produced by reacting phosphoric acid with a calcium source — typically calcium hydroxide (lime) or calcium carbonate (limestone) — under acidic conditions, MCP appears as a white to off-white crystalline powder or granular solid, freely soluble in water and dilute acids.
Property | Monocalcium Phosphate Monohydrate | Notes |
Chemical Formula | Ca(H₂PO₄)₂·H₂O | Anhydrous form also available |
CAS Number | 7758-23-8 | — |
Molecular Weight | 252.07 g/mol | Monohydrate |
Appearance | White crystalline powder or granular | Slight gray tint in feed grades |
Odor | Odorless | — |
Solubility in Water (20°C) | ~1.8 g/100 mL | Readily soluble; highest among calcium phosphates |
pH (1% aqueous solution) | 3.0–4.0 | Strongly acidic |
Phosphorus Content (P) | ~24.6% (anhydrous) / ~22.0–22.8% (feed grade) | Varies by grade and hydration |
Calcium Content (Ca) | ~15.9% (anhydrous) / ~15.0–18.0% (feed grade) | — |
Ca:P Molar Ratio | 0.50 | Lowest among industrial calcium phosphates |
Bulk Density | 0.8–1.2 g/cm³ | Powder; granular 0.9–1.1 g/cm³ |
Melting Point | Decomposes at ~200°C | Loses water of crystallization first |
Neutralizing Value | 80 (baking industry standard) | Grams of sodium bicarbonate neutralized per 100 g MCP |
This is the application that made MCP a household name — literally. Open any container of baking powder, and calcium phosphate monobasic is likely the acid component.
MCP in Double-Acting Baking Powders
Double-acting baking powders contain two acids: a fast-acting one (MCP) and a slow-acting one (typically sodium aluminum sulfate, SAS, or sodium acid pyrophosphate, SAPP). The MCP reacts immediately upon hydration, generating the initial gas lift in batters and doughs during mixing and bench time. The slow-acting acid kicks in during baking when heat triggers the second CO₂ release.
This dual-action system is why MCP appears in:
Self-rising flours
● — pre-blended with sodium bicarbonate and salt
Prepared cake mixes and pancake mixes
● — where the consumer simply adds liquid
Refrigerated dough products
● — biscuits, crescent rolls, and pizza doughs where controlled leavening during refrigerated storage is critical
Commercial bakery premixes
● — consistent, predictable rise at industrial scale
Food-Grade MCP Specifications
Parameter | FCC / Food Grade Specification |
Assay (as Ca) | 16.8%–18.3% (anhydrous basis) |
Loss on Drying | ≤1.0% (anhydrous) |
Fluoride | ≤0.005% (50 ppm) |
Arsenic | ≤3 mg/kg |
Lead | ≤2 mg/kg |
Heavy Metals (as Pb) | ≤10 mg/kg |
Acid-Insoluble Substances | ≤0.2% |
Sulfate | ≤0.5% |
Regulatory approvals: FDA 21 CFR 182.1217 (GRAS), EU Regulation (EC) No 231/2012 (E341i), JECFA specifications, Codex Alimentarius (INS 341i), China GB 1886.331-2021.
Competitive Landscape in Leavening
MCP competes with other leavening acids in the baking industry. Here is how it compares:
Leavening Acid | Reaction Speed | Neutralizing Value | Best Use Case |
Monocalcium Phosphate (MCP) | Very fast | 80 | Double-acting powders, self-rising flour |
Sodium Acid Pyrophosphate (SAPP) | Medium-slow | 72 | Donuts, cakes, refrigerated dough |
Sodium Aluminum Phosphate (SALP) | Slow (heat-activated) | 100 | Double-acting powders (slow component) |
Sodium Aluminum Sulfate (SAS) | Very slow | 100 | Bulk baking powders |
Glucono-delta-lactone (GDL) | Slow | 45 | Pizza dough, clean-label applications |
Cream of Tartar | Fast | 45 | Home baking, organic formulations |
MCP's advantage is its fast reaction at room temperature — it is the industry standard whenever immediate gas evolution is needed upon hydration.
The animal feed sector is the largest consumer of monocalcium phosphate by volume, accounting for an estimated 60–65% of global MCP production.
Why MCP for Feed — The Bioavailability Advantage
Phosphorus is a critical limiting nutrient in animal diets. Cereal grains and oilseed meals contain phosphorus, but 60–80% is locked in phytate (phytic acid), which monogastric animals — poultry, swine, and fish — cannot digest. Inorganic phosphate supplementation is therefore essential for profitable animal production.
MCP offers the highest phosphorus bioavailability of any feed phosphate. The reason is simple: it dissolves completely in the acidic environment of the animal's stomach, making phosphorus immediately available for absorption. This is measured as relative bioavailability compared to monosodium phosphate (the 100% reference standard):
Feed Phosphate | Relative Phosphorus Bioavailability | Best For |
MCP | ~100% | Aquaculture, young animals, high-performance diets |
DCP | ~95% | General poultry and swine |
MDCP (mono-dicalcium phosphate) | ~92–95% | General-purpose |
Defluorinated phosphate | ~85–90% | Ruminants, cost-sensitive formulations |
TCP | ~80–85% | Ruminants, slow-release applications |
Feed-Grade MCP Specifications
Parameter | Typical Feed Grade MCP Specification |
Total Phosphorus (P) | ≥22.0% (some specifications ≥22.3%) |
Water-Soluble Phosphorus (P) | ≥20.0% |
Calcium (Ca) | 15.0%–18.0% |
Fluorine (F) | ≤0.18% (≤0.10% for premium grades) |
Phosphorus Solubility in 2% Citric Acid | ≥98% |
Arsenic (As) | ≤10 mg/kg (≤20 mg/kg in some jurisdictions) |
Lead (Pb) | ≤15 mg/kg |
Cadmium (Cd) | ≤10 mg/kg |
Particle Size | Granular (0.2–1.0 mm typical) or powder (<0.2 mm) |
pH (1% solution) | 3.0–4.0 |
Regulatory frameworks: EU Regulation 68/2013 (feed materials), Chinese GB/T 22548-2017, AAFCO Official Publication.
MCP serves as the foundation for some of the world's most important phosphorus fertilizers — though it is rarely applied directly. Instead, it is a key intermediate and component in manufactured fertilizer products.
This is the chemistry behind triple superphosphate (TSP) — one of the most concentrated phosphorus fertilizers available, containing 44–48% P₂O₅, nearly all in the form of water-soluble monocalcium phosphate.
Q: What is the difference between calcium phosphate monobasic and monocalcium phosphate?
They are the same compound. "Calcium phosphate monobasic" (or "monobasic calcium phosphate") is the systematic IUPAC name. "Monocalcium phosphate" or "MCP" is the common industry name. Both refer to Ca(H₂PO₄)₂.
Q: Is monocalcium phosphate the same as the monocalcium phosphate in baking powder?
Yes. Baking powder typically contains sodium bicarbonate (the alkali), monocalcium phosphate (the fast-acting acid), and a slow-acting acid (such as sodium aluminum sulfate). The MCP provides the immediate leavening reaction when liquid is added.
Q: Which is better for animal feed — MCP or DCP?
It depends on the animal and life stage. MCP provides higher phosphorus bioavailability and is preferred for aquaculture, young animals (chicks, piglets, calves), and high-performance diets where maximizing phosphorus absorption is critical. DCP is more economical for general poultry and swine grower/finisher diets where the slightly lower bioavailability is acceptable. Many nutritionists use MCP in starter and early-grower phases and switch to DCP for later stages.
Q: Why is MCP more expensive than DCP?
MCP requires more phosphoric acid per ton of product (a 2:1 H₃PO₄-to-Ca ratio versus ~1:1 for DCP). Phosphoric acid is the main cost driver in calcium phosphate manufacturing, so MCP carries a proportionally higher raw material cost. Additionally, the tighter pH control during MCP production and — for food grades — the use of higher-purity thermal phosphoric acid add to the cost.
Q: Can MCP be used in organic food production?
In certified organic food production under USDA NOP and EU organic regulations, synthetic MCP is generally not permitted as a food additive. Organic baking relies on alternatives such as cream of tartar (potassium bitartrate), organic acids (citric, lactic), or yeast leavening for rise. For organic livestock production, natural mineral sources of phosphorus (bone meal, fishmeal, certain rock phosphates) are permitted where synthetic MCP is not.
