How is food grade Carboxymethyl Cellulose produced?

Food-grade CMC(carboxymethyl cellulose sodium)is produced by chemically modifying natural cellulose(from cotton or wood pulp)via a 3-core industrial process:alkalization→etherification→purification&drying.Food grade requires strict purity,low heavy metals,and compliance with standards like GB 1886.232 or FCC/E.

1.Raw Materials

Cellulose:High-purity refined cotton linter(90%cellulose)or wood pulp

Sodium hydroxide(NaOH):Alkali for activation

Monochloroacetic acid(MCA)or sodium chloroacetate:Etherifying agent

Solvent:Ethanol/isopropanol(water-miscible organic solvent,the solvent method—standard for food grade)

Acid:HCl for neutralization

2.Core Production Process(Solvent Method,Food-Grade Standard)

Step 1:Alkalization(Activation)

Mix refined cellulose with NaOH+aqueous alcohol in a reactor.

Heat(typically 60–75°C)to form sodium CMC.

Control degree of substitution(DS):0.6–0.95 for food grade.

Step 3:Neutralization&Washing(Critical for Food Purity)

Neutralize excess NaOH with HCl.

Wash repeatedly with aqueous alcohol to remove byproducts:

NaCl(salt)

Sodium glycolate

Unreacted chemicals

Food grade requires>90%purity and near-zero residual salts/heavy metals.

Step 4:Drying&Milling

Filter→press→dry(hot air)→mill to fine white powder.

Sieve to uniform particle size.

Test:viscosity,DS,pH,purity,heavy metals(Pb,As,Cd<1 ppm).

3.Food-Grade vs.Technical Grade

Food grade:High-purity solvent method,extensive washing,low salt/heavy metals,DS 0.6–0.95.

Technical grade:Lower purity,water-media process,higher salt,not for food.

4.Key Food-Grade Specifications(GB 1886.232–2016)

Assay(dry basis):95.0–105.0%

Degree of substitution(DS):0.2–1.5(food:0.6–0.95)

Heavy metals(Pb):≤5 mg/kg

Loss on drying:≤10.0%

pH(1%solution):6.0–8.5

Summary

Food-grade CMC is purified cellulose ether made via:

Cellulose→Alkali→Etherify→Wash(purify)→Dry→Powder

It’s safe,widely used in foods,and meets strict global food standards.

References

GB/T 7714

Food Safety Standard for Food Additive Sodium Carboxymethyl Cellulose(GB 1886.232-2016).National Health and Family Planning Commission of the People's Republic of China,2016.

MLA

Saha,Dipti,and Suresh Bhattacharya."Hydrocolloids as thickening and gelling agents in food:A critical review."Journal of Food Science and Technology,vol.47,no.6,2010,pp.587–601.

APA 

National Health and Family Planning Commission of the People's Republic of China.(2016).Food safety standard for food additive sodium carboxymethyl cellulose(GB 1886.232-2016).