Carrageenan

Carrrageenans are a family of linear sulfated polysccharides that are extracted from red seaweeds. There are several varieties of carrageen used in __cooking__ and baking. Kappa-carrageenan is used mostly in breading and batter due to its gelling nature. Lambda carrageenan is a non gelling variety that assists in binding, retaining moisture and in contributing to viscosity in sweet doughs. Iota carrageenan is used primarily in fruit applications and requires calcium ions to develop a heat-reversible and flexible gel. [|[1]] Gelatinous extracts of the // [|Chondrus crispus] // ( [|Irish Moss] ) seaweed have been used as food additives for hundreds of years. [|[2]] Carrageenan is a vegetarian and vegan alternative to gelatin.

Properties
Carrageenans are large, highly flexible molecules that curl forming helical structures. This gives them the ability to __form__ a variety of different gels at room temperature. They are widely used in the food and other industries as thickening and stabilizing agents. A particular advantage is that they are pseudoplastic—they thin under shear stress and recover their viscosity once the stress is removed. This means that they are easy to pump but stiffen again afterwards. All carrageenans are high-molecular-weight polysaccharides made up of repeating galactose units and 3,6 anhydrogalactose (3,6-AG), both sulfated and nonsulfated. The units are joined by alternating alpha 1–3 and beta 1–4 glycosidic linkages. There are three main commercial __classes__ of carrageenan: The primary differences that influence the properties of kappa, iota, and lambda carrageenan are the number and position of the ester sulfate groups on the repeating galactose units. Higher levels of ester sulfate lower the solubility temperature of the carrageenan and produce lower strength gels, or contribute to gel inhibition (lambda carrageenan). Many red algal species produce different types of carrageenans during their developmental history. For instance, the genus //Gigartina// produces mainly kappa carrageenans during its gametophytic stage, and lambda carrageenans during its sporophytic stage. See [|Alternation of generations]. All are soluble in hot water, but, in cold water, only the lambda form (and the sodium salts of the other two) are soluble. When used in food products, carrageenan has the [|EU] additive E-number E407 or E407a when present as "processed eucheuma seaweed", and is commonly used as an emulsifier. In parts of Scotland (where it is known as (An) Cairgean in Scottish Gaelic) and Ireland (variety used is [|Chondrus Crispus] known in Irish Gaelic variously as carraigín [little rock], fiadháin [wild stuff], clúimhín cait [cat's puff], mathair an duilisg [mother of seaweeds], ceann donn [red head]), it is known as [|Carrageen Moss] it is boiled in milk and strained, before sugar and other flavourings such as vanilla, cinnamon, brandy, or whisky are added. The end-product is a kind of jelly similar to pannacotta, tapioca, or blancmange. When iota carrageenan is combined with [|sodium stearoyl lactylate] (SSL), a synergistic effect is created, allowing for stabilizing/emulsifying not obtained with any other type of carrageenan (kappa/lambda) or with other emulsifiers (mono and diglycerides, etc.). SSL combined with iota carrageenan is capable of producing emulsions under both hot and cold conditions using either vegetable or animal fat.
 * **Kappa** forms strong, rigid gels in the presence of potassium ions; it reacts with dairy proteins. It is sourced mainly from //Kappaphycus alvarezii// [|[3]].
 * **Iota** forms soft gels in the presence of calcium ions. It is produced mainly from //Eucheuma denticulatum// [|[3]].
 * **Lambda** does not gel, and is used to thicken dairy products. The most common source is //Gigartina// from South America.

Production
Although carrageenans were introduced on an industrial scale in the 1930s, they were first used in China around 600 BC (where //Gigartina// was used) and in Ireland around 400 AD.[// [|citation needed] //] The largest producer currently is the Philippines, where cultivated seaweed produces about 80% of the world supply. [|[4]] The most commonly used are //E. cottonii// (//Kappaphycus alvarezii, K.striatum//) and//E. spinosum// (//Eucheuma denticulatum//), which together provide about three-quarters of the world production. These grow from the sea surface to a depth of about 2 metres. The seaweed is normally grown on nylon lines strung between bamboo floats, and is harvested after three months or so, when each plant weighs around 1 kg. The //E. cottonii// variety has been reclassified as //Kappaphycus cottonii// by Maxwell Doty (1988), thereby introducing the genus //Kappaphycus//, on the basis of the phycocolloids produced (namely kappa carrageenan).[// [|citation needed] //] After harvest, the seaweed is dried, baled, and sent to the carrageenan manufacturer. There the seaweed is ground, sifted to remove impurities such as sand, and washed thoroughly. After treatment with hot alkali solution (e.g., 5–8% potassium hydroxide), the cellulose is removed from the carrageenan by centrifugation and filtration. The resulting carrageenan solution is then concentrated by evaporation. It is dried and ground to specification. code          cleaned & washed seaweed ↓                               extraction ↓                            coarse filtration   → seaweed residue ↓                             fine filtration    → used filter aids ↓                concentration ↓ preparation with Kcl                        preparation with alcohol ↓                                         ↓   gel pressing                                      alcohol recovery ↓                                         |      drying                                        | ↓                                         ↓        milling                                   drying ↓                                         ↓      blending                                    milling ↓                                         ↓     get refined carrageenan                     blending ↓                                            refined carrageenan

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