Introduction
Calcium Citrate Tetrahydrate (Tricalcium Citrate Tetrahydrate) is the calcium salt of citric acid, occurring as a white, odorless, fine crystalline powder. It is commercially produced by the neutralization of citric acid with a calcium source such as calcium carbonate or calcium hydroxide, followed by crystallization, drying, and milling. The tetrahydrate form (CAS 5785-44-4) is the commercially mainstream form of calcium citrate, widely used across food, pharmaceutical, and supplement industries.
As a highly bioavailable organic calcium salt, calcium citrate tetrahydrate offers distinct advantages over inorganic calcium sources such as calcium carbonate. Its absorption is independent of gastric acid levels, meaning it can be taken with or without food without compromising absorption efficiency. Calcium citrate tetrahydrate provides approximately 21% elemental calcium by weight-significantly higher than calcium gluconate (9%) and calcium lactate (13%)-making it an efficient choice for calcium fortification.
In the food industry, calcium citrate (E333) is approved as a multifunctional additive serving as a calcium fortifier, acidity regulator, firming agent, sequestrant (chelating agent), and anti-caking agent. In dietary supplements and pharmaceuticals, it is widely used as a well-absorbed calcium source for the prevention and treatment of calcium deficiency and bone health management.
Certificate of Analysis (COA)
| Item | Specification | Result | Method |
|---|---|---|---|
| Physical Description | |||
| Appearance | White to off-white powder | Conforms | Visual |
| Odor | Odorless | Conforms | Organoleptic |
| Particle Size (through 80–200 mesh) | ≥80% | Conforms | Screening |
| Chemical Tests | |||
| Assay (as Ca₃(C₆H₅O₇)₂·4H₂O) | 97.5% – 100.5% | 98.50% | Titration |
| Calcium Content | Approx. 21% | 21.30% | Titration |
| Loss on Drying (150°C, 4h) | 10.0% – 14.0% | 12.10% | USP <731> |
| pH (1% suspension) | 6.0 – 8.0 | 6.80 | USP <791> |
| Identification (Citrate) | Passes test | Passes | USP |
| Heavy Metals | |||
| Lead (Pb) | ≤2 mg/kg | Conforms | ICP-MS |
| Arsenic (As) | ≤1 mg/kg | Conforms | ICP-MS |
| Mercury (Hg) | ≤1 mg/kg | Conforms | ICP-MS |
| Heavy Metals (as Pb) | ≤10 mg/kg | Conforms | USP <231> |
| Other Impurities | |||
| Fluoride | ≤30 ppm | Conforms | USP |
| Acid-Insoluble Substances | ≤0.2% | Conforms | USP |
| Microbiological Control | |||
| Total Plate Count | ≤1,000 cfu/g | Conforms | USP <2021> |
| Yeast & Mold | ≤100 cfu/g | Conforms | USP <2021> |
| Salmonella in 25g | Negative | Negative | USP <2022> |
| E. coli | Negative | Negative | USP <2022> |
| Conclusion | Conforms to specification |
Note: Full COAs for Pharmaceutical Grade and Direct Compression Grade are available upon request.
Calcium Citrate Benefits
Nutritional & Health Benefits
- Highly Bioavailable Calcium Source: Calcium citrate tetrahydrate offers superior absorption and gastrointestinal tolerance compared to inorganic calcium salts.
- Gastric Acid Independent: Effective even for individuals with low stomach acid, including the elderly and those taking acid-reducing medications.
- Bone Health Support: Provides essential calcium for bone formation, maintenance, and prevention of osteoporosis.
- Kidney Stone Risk Reduction: The citrate component binds to calcium in the urine, reducing the risk of calcium oxalate stone formation.
- Gentle on the Digestive System: Does not typically cause gastrointestinal discomfort, bloating, or constipation-common side effects associated with calcium carbonate.
- High Elemental Calcium Content: Provides 21% elemental calcium-significantly higher than calcium gluconate (9%) and calcium lactate (13%).
Functional Benefits (Food & Beverage)
- Calcium Fortification: Enriches foods and beverages with calcium without significantly altering taste or texture.
- Texture Improvement: Acts as a firming agent in canned fruits, vegetables, and dairy products.
- Acidity Regulation: Buffers pH in beverages, jams, and processed foods.
- Anti-Caking: Prevents clumping and improves flowability in powdered mixes, protein powders, and dry blends.
- Chelation: Binds metal ions to prevent oxidation, discoloration, and off-flavors.
Pharmaceutical Benefits (as Excipient)
- Tableting Aid: Excellent compressibility and flow properties for direct compression tablet formulations.
- Taste Masking: Neutral, pleasant taste suitable for chewable tablets and pediatric formulations.
- Formulation Stability: Supports pH balance and enhances formulation stability.
What is Calcium Citrate Used For?
Dietary Supplements
- Calcium Supplements: Tablets, capsules, softgels, chewable tablets, and powder blends for bone health and calcium supplementation
- Multivitamin/Mineral Formulations: Combined with other minerals and vitamins
- Sports Nutrition: Post-exercise recovery and bone health formulations
- Senior Nutrition: Gentle on the digestive system, suitable for elderly populations
Food & Beverage
- Calcium Fortification: Infant formula, follow-on formula, and baby foods
- Dairy Products: Milk, yogurt, cheese, and dairy alternatives
- Beverages: Fruit juices, fortified waters, sports drinks, and powdered drink mixes
- Cereal & Grain Products: Breakfast cereals, bread, pasta, and bakery goods
- Confectionery: Chewing gums, candies, and chocolate
- Meat Products: As a firming agent and texture improver
- Jams & Jellies: As a firming agent and gelling aid
Pharmaceuticals
- Calcium Preparations: Prevention and treatment of calcium deficiency, osteoporosis, and osteomalacia/rickets
- Pharmaceutical Excipient: Stabilizer, solubilizer, and pH regulator in drug formulations
- Oral Care: Gentle abrasive agent in toothpaste; supports tooth remineralization
Cosmetics & Personal Care
- Skincare: Creams, lotions, and masks
- Oral Care: Toothpaste and mouthwash formulations
- Clay Masks: As a controlled-release cross-linking agent with alginate
Animal Feed & Agriculture
- Calcium Supplement: Animal feed fortification
- Feed Additive: As a preservative, anti-mold agent, and acidity regulator
Frequently Asked Questions (FAQ)
Q: What is the difference between calcium citrate tetrahydrate and anhydrous calcium citrate?
A: Calcium citrate tetrahydrate (CAS 5785-44-4) contains four molecules of water of crystallization and is the commercially mainstream form. Anhydrous calcium citrate (CAS 813-94-5) has had the water removed through additional drying. The tetrahydrate form contains approximately 21% elemental calcium, while the anhydrous form contains approximately 24.1%. The tetrahydrate form is generally preferred for most food and supplement applications due to its stability and handling characteristics.
Q: What is the difference between calcium citrate tetrahydrate and calcium carbonate?
A: Calcium citrate is an organic calcium salt with superior bioavailability-approximately 25% higher absorption than calcium carbonate. Unlike calcium carbonate, calcium citrate does not require stomach acid for absorption and can be taken with or without food. Calcium citrate is also less likely to cause gastrointestinal discomfort or constipation. However, calcium carbonate provides a higher percentage of elemental calcium (40% vs. 21% for calcium citrate tetrahydrate), making it more cost-effective for high-dose applications.
Q: What is the recommended dosage for calcium citrate tetrahydrate as a dietary supplement?
A: Calcium supplementation recommendations vary by age, gender, and health status. The general Recommended Dietary Allowance (RDA) for calcium is 1,000–1,200 mg of elemental calcium per day for adults. For calcium citrate tetrahydrate, this corresponds to approximately 4,800–5,700 mg of calcium citrate (since it provides 21% elemental calcium). We recommend consulting with a healthcare professional or formulation specialist for application-specific guidance.
Q: Is calcium citrate tetrahydrate safe for consumption?
A: Yes. The U.S. FDA has affirmed calcium citrate as GRAS (Generally Recognized as Safe) for use as a direct human food ingredient. EFSA has assessed calcium citrates (E333) as safe for use in food. It is approved for use in the EU (E333), USA (GRAS), China (GB1903.14-2016), and numerous other countries.
Q: What is the difference between food grade, pharmaceutical grade, and direct compression grade?
A: Food Grade (FCC) meets Food Chemical Codex requirements and is suitable for all food, beverage, and nutritional supplement applications. Pharmaceutical Grade (USP/NF) meets the stricter purity requirements of the United States Pharmacopeia and is used as an excipient in drug formulations. Direct Compression Grade is specially processed to exhibit optimal flow properties and compressibility for tablet manufacturing. The key differences lie in purity specifications, particle size distribution, and flow characteristics.
Q: What particle sizes are available?
A: We offer multiple particle size grades including standard powder (80–200 mesh), fine powder, granular forms, and custom sieve cuts. Bulk density is typically 400–500 kg/m³ (loose). Direct compression grades are optimized for die-fill stability and tablet weight consistency.
Why Choose Huilin Bio-Tech?
Your Professional Manufacturing & Sourcing Partner
We are more than a supplier - we are a comprehensive supply chain partner dedicated to high-quality ingredients, custom formulations, and finished products across multiple industries.
Professional Manufacturer: Xi'an Huilin Bio-tech Co., Ltd. is a high-tech biotechnology company specializing in the production, R&D, and export of natural botanical extracts.
Quality Assurance: Every batch undergoes rigorous testing for capsaicin content (HPLC), heavy metals (ICP-MS), and microbiological purity to ensure consistent quality and safety.
Flexible Specifications: We offer a wide range of specifications from 1% to 98% capsaicin content to meet diverse application requirements.
Customization Capabilities: We offer flexible packaging options and custom formulations to meet diverse customer requirements.
Supply Chain Reliability: With established supply chains and robust production capacity, we ensure timely delivery and stable supply for bulk orders.
Technical Support: Our experienced R&D team provides formulation guidance and technical support throughout your product development process.
Global Compliance: Products are manufactured in compliance with international quality standards and regulatory requirements.
For inquiries, quotations, or sample requests, please contact: sales@huilinbio-tech.com
References
1. U.S. Food and Drug Administration. Final Rules: Food Additives and Color Additives – Citric Acid and Certain Citrate Derivatives; Affirmation of GRAS Status as Direct Human Food Ingredients. Federal Register. Calcium citrate is affirmed as GRAS for use as a direct human food ingredient.
Link: https://hfpappexternal.fda.gov/scripts/fdcc/index.cfm?id=59FR63894&set=FinalRules
2. European Commission Regulation (EU) No 231/2012. Specifications for food additives – E 333 (iii) Tricalcium Citrate. Assay: Not less than 97.5% on the anhydrous basis; Loss on drying: Not more than 14.0% determined by drying at 180°C for four hours; Fluoride: Not more than 30 mg/kg (for infant food).
Link: https://eur-lex.europa.eu/eli/reg/2012/231/oj
3. Calcium citrate tetrahydrate – Wikipedia. Calcium makes up 24.1% of calcium citrate (anhydrous) and 21.1% of calcium citrate (tetrahydrate) by mass.
Link: https://en.wikipedia.org/wiki/Calcium_citrate
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