- H. J. F. Zunft et al.,Eur. J. Nutr., 42 , 235
(2003).
- H. Loeb et al.,J. Pediatr. Gastroenterol.
Nutr., 8 , 480 (1989).
- A. E. Harmuth-Hoene et al.,Z. Ernahru-
ngswiss., 21 , 202 (1982).
20. J. Ott,The Cacahuatl Eater: Ruminations
of an Unabashed Chocolate Addict,
Natural Products, Co., Vashon, WA,
1985.
21. S. Aksit et al.,Paediatr. Perinat. Epide-
miol., 12 , 176 (1998).
CARRAGEENAN
Source: Chondrus crispus (L.) Stackh.,
Eucheuma, andGigartinaspecies or relat-
ed red algae (seaweeds) of the class
Rhodophyceae.
Common/vernacular names: Carrageenan,
carrageenin, carragheenan, chondrus extract,
Irish moss extract.
GENERAL DESCRIPTION
Carrageenan is a seaweed gum (hydrocolloid)
obtainedfrom various red algaegrowingalong
the Atlantic coast of Europe and North Amer-
ica, withC.crispus(Irish moss) as its major
source. It occurs in the intercellular matrix and
cell walls of the algae and constitutes 60–80%
of their salt-free dry weight.1–3Its primary use
is as a food stabilizer.
In the manufacture of carrageenan, the
dried seaweed is first cleaned with cold water
and mechanical devices to remove salt and
other extraneous materials. It is then extracted
with hot water containing calcium or sodium
hydroxide.The extract is clarified byfiltration,
its pH adjusted to slightly basic, and carra-
geenan is obtained either by direct drum or roll
drying of the filtrate or by precipitation with
alcohol (e.g., ethyl or isopropyl), depending
on the type or purity desired.4,5The United
States and European countries (e.g., Denmark,
France, and Spain) are the major carrageenan
producers, with the United States being by far
the largest.
Carrageenan comes in many types with
different solubilities and gel characteristics,
depending on the process and types of algae
used for its manufacture. It readily dissolves in
water to form viscous solutions or gels, de-
pending on its chemical composition. Its re-
action to heating and shearing forces also
depends on its chemical nature.
Carrageenan has high reactivity with cer-
tain proteins, particularly milk protein, to
form weak to strong gels.
CHEMICAL COMPOSITION
Carrageenan is a sulfated, straight-chain poly-
galactan composed of residues ofD-galactose
and 3,6-anhydro-D-galactose with a molecular
weight usually of 100,000–500,000. It con-
tains a high content of sulfate (20–40% dry
weight basis). The number and position of
the sulfate groups and the ratio of galactose
to 3,6-anhydrogalactose vary greatly. Carra-
geenan generally contains two major frac-
tions: a gelling fraction calledk-carrageenan
and a nongelling fraction calledl-carrageen-
an;k-carrageenan containsD-galactose, 3,6-
anhydro-D-galactose and ester sulfate groups,
whilel-carrageenan containsD-galactose and
its monosulfate and disulfate esters. Other
types of carrageenan includei-carrageenan,
which is composed mainly of monosulfates
ofD-galactose and 3,6-anhydro-D-galactose
(FURIA).2,6,7
l-Carrageenan is readily soluble in cold
water to form a viscous solution regardless of
the cations present, whereask-carrageenan is
precipitated by potassium ions. The potassium
salt of carrageenan, however, is soluble in
water on heating and forms an elastic gel on
cooling; the elasticity or rigidity of the gel
Carrageenan 145
