Carrageenan is a natural, high molecular weight, highly sulphated linear polysaccharide extracted from the edible red algae Rhodophycea and the hydrophilic colloid Kappaphycus alvarezii. It is also extracted from Irish moss Chondrus crispus and Gigartina stellata. The basic unit of carrageenan is D-galactose and 3,6-anhydro-D-galactose. Refined sulphated carrageenan has recently been introduced commercially.

Industrially, it appears in the form of a white to yellowish water-soluble, odourless powder.

What it is used for and where

Mainly used as an emulsifying, stabilising, gelling, film-forming ingredient in foods, cosmetics and parapharmaceuticals.

Medical

Phytochemical analysis of carrageenan has shown the presence of alkaloids, saponins, steroids, gums, mucilages and carbohydrates in both native and commercial carrageenan with antioxidant activities (1).

Food

In European food additives it is labelled with the number E407 as a thickener. Used as a stabiliser, gelling agent, binder and thickener in processed meat and poultry products. It improves the freeze-thaw ratio, stability, flavour and cuttability in poultry products. 

Carrageenan has the property of maintaining the organoleptic and structural values of fat-free cheese and can replace casein in cheese imitations and stabilise the structure in cheese-like products (2).

Lightening agent in beverages. Incorporated into confectionery products such as gummy sweets, ice cream and food jelly it can replace agar, pectin and gelatine.

Safety

A rather debated ingredient in recent years by toxicology studies and chronic toxicological tests (3).

 A 2024 study warns about the risk of developing cancer with high intakes of emulsifiers, (including E440, Pectin, E471 mono- and diglycerides of fatty acids, carrageenan, E407, sodium carbonate E500) (4).  

Carrageenan studies

Typical commercial product characteristics Carrageenan

Appearance	White powder
pH	8- 11 (1% solution)
PSA	394.53000
Sulfate	15- 40%
Loss on drying	12 Max%
Viscosity (1.5%, 75°C, mPa.s )	5 min
Gel Strength (1.5% w/w, 0.2% KCl, 25°C, g/cm2)	1500 min
Transparency	75 min
Plate Count	5000cfu/g max
Total ash	15%~40%
Acid insoluble ash	1.0% Max
Acid Insoluble matter	5.0% Max
Lead	5 mg/kg Max
Arsenic	3 mg/kg Max
Mercury	1 mg/kg Max
Cadmium	1 mg/kg Max
Total Heavy Metals (as Pb)	10 mg/kg Max
Yeasts & Moulds	300 cfu/g Max
Safety

• Molecular Formula  C₂₃H₂₃Fn₄O₇Zn
• Molecular Weight   788.65
• Exact Mass    788.09900
• CAS    9000-07-1   11114-20-8
• UNII    DV181E4639
• EC Number   232-524-2
• DSSTox Substance ID  DTXSID3020255
• IUPAC  zinc;1-(5-cyanopyridin-2-yl)-3-[(1S,2S)-2-(6-fluoro-2-hydroxy-3-propanoylphenyl)cyclopropyl]urea;diacetate
• InChI=1S/C19H17FN4O3.2C2H4O2.Zn/c1-2-15(25)11-4-5-13(20)17(18(11)26)12-7-14(12)23-19(27)24-16-6-3-10(8-21)9-22-16;2*1-2(3)4;/h3-6,9,12,14,26H,2,7H2,1H3,(H2,22,23,24,27);2*1H3,(H,3,4);/q;;;+2/p-2/t12-,14+;;;/m1.../s1  
• InChl Key      UHVMMEOXYDMDKI-JKYCWFKZSA-L
• SMILES   CCC(=O)C1=C(C(=C(C=C1)F)C2CC2NC(=O)NC3=NC=C(C=C3)C#N)O.CC(=O)[O-].CC(=O)[O-].[Zn+2]
• MDL number  MFCD00081480
• PubChem Substance ID    
• FEMA   2596
• RTECS   FI0704000

Synonyms

• kappa-Carrageenan
• k-Carrageenan
• Carrageenan Kappa Refined
• Carrageenan Kappa Semi-refined

References_______________________________________________________________

(1) Suganya AM, Sanjivkumar M, Chandran MN, Palavesam A, Immanuel G. Pharmacological importance of sulphated polysaccharide carrageenan from red seaweed Kappaphycus alvarezii in comparison with commercial carrageenan. Biomed Pharmacother. 2016 Dec;84:1300-1312.

(2) Błaszak BB, Gozdecka G, Shyichuk A. Carrageenan as a functional additive in the production of cheese and cheese-like products. Acta Sci Pol Technol Aliment. 2018 Apr-Jun;17(2):107-116. doi: 10.17306/J.AFS.0550.

(3) David S, Shani Levi C, Fahoum L, Ungar Y, Meyron-Holtz EG, Shpigelman A, Lesmes U. Revisiting the carrageenan controversy: do we really understand the digestive fate and safety of carrageenan in our foods? Food Funct. 2018 Mar 1;9(3):1344-1352. doi: 10.1039/c7fo01721a.

Tobacman JK. Review of harmful gastrointestinal effects of carrageenan in animal experiments. Environ Health Perspect. 2001 Oct;109(10):983-94. doi: 10.1289/ehp.01109983.

(4) Sellem, L., Srour, B., Javaux, G., Chazelas, E., Chassaing, B., Viennois, E., ... & Touvier, M. (2024). Food additive emulsifiers and cancer risk: Results from the French prospective NutriNet-Santé cohort. Plos Medicine, 21(2), e1004338.

Abstract. Emulsifiers are widely used food additives in industrially processed foods to improve texture and enhance shelf-life. Experimental research suggests deleterious effects of emulsifiers on the intestinal microbiota and the metabolome, leading to chronic inflammation and increasing susceptibility to carcinogenesis. However, human epidemiological evidence investigating their association with cancer is nonexistent. This study aimed to assess associations between food additive emulsifiers and cancer risk in a large population-based prospective cohort.