The chemical composition of food grade sodium hexametaphosphate and industrial grade sodium hexametaphosphate is Na₆P₆O₁₈, but there are significant differences in purity, impurity content, production process and use. The following are the main differences:
- Purity and impurity control
Food grade:
Higher purity (usually ≥98%), heavy metals (such as lead, arsenic, mercury), fluoride and other harmful impurities are strictly limited, in line with international standards (such as **GB 1886.4-2020 (China), FCC (USA), JECFA (United Nations)**, etc.).
Must pass food safety tests (such as microbial limits, toxic substance residues).
Industrial grade:
Lower purity (may contain more by-products or unreacted raw materials), loose impurity restrictions, may contain heavy metals, sulfides, etc., cannot be used for food.
- Production process
Food grade:
Use high-purity raw materials (such as food-grade phosphoric acid, sodium carbonate), the production environment complies with GMP (Good Manufacturing Practice), and avoids cross contamination. May add purification steps (such as recrystallization, ion exchange).
Industrial grade:
The process requirements are lower, cost is prioritized, and industrial raw materials (such as yellow phosphorus or low-purity phosphoric acid) may be used.
- Applications: Food Grade: Food additive (E452i) acts as a humectant, pH adjuster, and chelating agent for metal ions. Commonly used in processed meats, drinks, and dairy products. The amount added must be clearly stated (generally limited to 0.1-5g/kg, depending on the product). Industrial Grade:
Used in water treatment (as an antiscaling agent), detergents, ceramic dispersants, and metal surface treatments. May contain ingredients harmful to human health. - Regulations and Certifications:
Food Grade:
Requires a food production license (e.g., China's SC certification), along with FDA (USA) and EFSA (EU) approvals. Packaging must clearly label it as a 'food additive' and specify the applicable standards. Industrial Grade: Only needs to meet industrial chemical standards (such as HG/T 2519-2017). - Pricing:
Food-grade products are considerably more expensive than industrial-grade due to the costs of purification and certification. - Precautions
No mixing: If industrial-grade sodium hexametaphosphate is used in food by mistake, it may cause heavy metal poisoning or food safety accidents.
When purchasing: Look for food-grade qualifications (test report, production license number, etc.).
If specific standard limits or application details are required, further requirements can be provided.