Carrageenan, also known as Irish Carrageenan, is a mixture of various substances which are extracted from marine red algae, there are mainly four types of commercial carrageenan: Kappa carrageenan, Iota carrageenan, Lambda carrageenan and kappaⅡ carrageenan., Kappa Carrageenan owns better thickening, emulsfying characteristics, elasticity and water-retaining property. Even being boiled under neutral and alkaline condition, it won't be hydrolyzed. So carrageenan is widely used in food, medicinal and chemical industry.

Using carrageenans is meat industry: Carragenans – semi-refined as well as refined are widely used in meat industry.

There are three main commercial classes of carrageenan:

Kappa forms a strong rigid gel in the presence of potassium ions; it reacts with milk proteins. It is mainly derived from Kappaphycus alvarezii [3]. Iota forms soft gel in the presence of calcium ions. It is mainly from Eucheuma denticulatum. Lambda does not gel and is used to thicken dairy products. The most common source is Gigartina from South America. The main differences affecting the properties of κ, ι and λ keratine gels are the number and position of ester sulfate groups on the repeating galactose units. Higher levels of sulphate reduce the dissolution temperature of keratoconid and produce a lower strength gel, or contribute to gel inhibition (λ keratoconid).

Many red algal species produce different types of cuticular gels during their developmental history. For example, the genus Gigartina produces predominantly κ-hornblende gels during its gametophyte stage and λ-hornblende gels during its sporophyte stage. See alternation of generations.

All are soluble in hot water, but in cold water only the λ form (and the sodium salts of the other two) is soluble.

When used in food, carrageenan has the EU Additive E-No. E407 or E407a, and is usually used as an emulsifier when present as ‘processed unicorn seaweed’.

In parts of Scotland (where it is known as (An)Cairgean in Scottish Gaelic) and Ireland (where the species used is Chondrus Crispus in Irish Gaelic, like carraigín [small stone], fiadháin [wild thing], clúimhíncait [cat's puff], mathair an duilisgait [cat's puff], and clúimhíncait [cat's puff]), it is often used as an emulsifier. mathair an duilisg [mother of seaweed], ceann donn [red head]), it is known as Carrageen Moss, which is boiled and deformed in milk, then sugar and other flavourings such as vanilla, cinnamon, brandy or whisky are added. The end product is a jelly similar to pannacotta, tapioca or blancmange.

When ι-hornbeam is combined with sodium stearoyl lactylate (SSL), a synergistic effect is produced, allowing stabilisation and emulsification that cannot be obtained with any other type of hornbeam (κ/λ) or with other emulsifiers (glycerol mono- and diglycerides, etc.). SSL, in combination with iota carob gum, enables the production of emulsions using vegetable or animal fats in both hot and cold conditions.

In the United States, carob gum is an ingredient in soya milk sold under the Whole Foods brand.