Although there are thousands of global carrageenophyte species, less than 20 are used commercially to produce carrageenan (GGN) – a gelling, thickening and stabilizer used in many dairy, meat and other products including beer, toothpaste, shampoo, air freshener gels, soy milk, diet sodas, pet foods, personal lubricants and food.
Carrageenan is Safe
The most important products in terms of volume of carrageenan used are flavored milk (particularly chocolate), frozen desserts, ready-to-eat desserts, soy milk, and cottage cheese dressings It may be seen on labels as E407.
Carrageenan from Irish Moss has been used since the 15th Century and is an alternative for vegetarians or vegans to gelatin.
For more information, check out the details on Wikipedia.
The primary commercial warm water–cultivated species list includes Kappaphycus alverezii (previously Eucheuma cottonii or ‘cottonii’) and Eucheuma denticulatum ( Previously E. spinosum or called ‘Spinosum’). ‘Cottonii’ produces 90% kappa-CGN and spinosum is 85% iota-CGN. These are spiny, bushy seaweeds that grow to about 50 cm high in reef or lagoon regions primarily in the Philippines, Indonesia, and East Africa. These species are farmed in tropical waters with an 8- to 12-week harvest cycle and available year round. Only one CGN type is extracted from each of these two species.
In contrast, cold-water species are harvested annually during the summer months. The primary commercial species includes Chondrus crispus/Gigartina stellata (‘Irish Moss’), which comprise small bushy seaweeds about 10 cm high and widely distributed around the coasts of the North Atlantic ocean, and the much larger Gigartina species harvested off the West Coast of South America (primarily Chile). These wild-harvested seaweeds comprise both haploid and diploid plants which grow together and appear identical. Haploid plants produce kappa-CGN; diploid plants produce lambda-CGN. Consequently, CGN extracted from cold-water species is a mix of kappa-CGN and lambda-CGN in variable ratio depending on the season and location.
All commercial seaweed species are immediately and thoroughly dried to target moisture in the range 18–35% depending on the species and natural salt content from the seawater. The dried seaweeds are baled and shipped to the CGN manufacturing plants which are found in various countries including Indonesia, China, France.
Kappa–Carrageenan = Firm Gel
Kappa-carrageenan yields a strong gel often described as firm and brittle in the presence of potassium ions, and may have syneresis. The kappa structure is a linear polysaccharide with one sulfate group per two galactose molecules and assumes a helical network that is only strengthened with potassium present. Kappa needs to be solubilized in hot water, but the sodium salts of kappa-carrageenan can be soluble in cold water. The resulting gels are not freeze-thaw stable.
Kappa-carrageenan is used in dairy applications with success because it complexes with kappa-casein to form a pourable gel formation. This link allows particles like cocoa (EU) in chocolate milk or whey proteins in other dairy products to remain suspended. In ice cream, the kappa form is used to stabilize air bubbles. In processed cheese , it can be used to reduce the amount of natural cheese without changing manufacturability or finished product texture.
Kappa-carrageenan is also commonly used in meat processing. It enables higher moisture content in meat products like sausages and cooked hams, which results in better yields and improved slicing. In low-fat meat products, using it will result in eating qualities which mimic full fat meat products
Iota–Carrageenan = Elastic Gel
Like kappa, the Iota-carrageenan structure is also a linear polysaccharide which assumes a helical conformation but with two sulfate groups per two galactose molecules. Iota forms a soft elastic gel especially in the presence of calcium ions and the resulting gel strength is ionic strength dependent. Unlike kappa, iota-carrageenan forms gels with freeze-thaw stability and is less likely to undergo syneresis. The iota form is soluble in hot water, and only the sodium salts of iota-carrageenan are soluble in cold water.
Iota-carrageenan gels have the ability to break apart during mechanical action and reform once the mechanical action stops, which is known as thixotropy. This property is helpful in cold-filled products. Within food applications, low usage levels of iota-carrageenan are used to suspend particulates within salad dressings (EU) and other beverages like soy milk (EU). At higher usage levels, iota creates a stronger gel and is used in products like pet foods to create gravy.
William R. Blakemore, in Reference Module in Food Science, Science Direct, 2016
Jill Frank 2015. Carrageenan Deep Dive – Kappa, Iota and Lambda