Introduction about Carrageenan
Carrageenan is a hydrocolloid extracted from some red algae seaweed. Its chemical structure consists of calcium, potassium, sodium and ammonium salts from polysaccharide sulfate made up of galactose and dehydrated galactose. Due to the different combining forms of sulfate, it can be classified into three types: K (Kappa), I (Iota), and L (Lambda).
History of Carrageenan
The use of carrageenan originated from hundreds of years ago. The southern coasts of Ireland produced a kind of seaweed, commonly known as Irish moss and now named Chondrus crispus. The local people often collected it, poured into milk and boiled with sugar, then cool and eat it after coagulation. In the early 18th century, a kind of powder was made of this seaweed by Irish people and introduced to America. Afterwards, companies began the commercialized production of this powder and started selling by the name of sea moss farina. It was widely used in milk and many other kinds of food. In the 19th century, America began the industrial extraction of carrageenan and the carrageenan industry finally developed in America until the 1940s.
Structural Formula of Carrageenan
Molecular Formula: （C12H18O9）n
Chemical Properties of Carrageenan Gel
It is insoluble in cold water and organic solvents, but can swell into the gelled block. However, it is easily soluble in hot water and semitransparent colloidal solution (The solution rate can be enhanced in water over 70℃).
● Gelling Property
It can produce a kind of thermal reversible gel in the presence of potassium ion.
● Thickening Property
At low concentration, it can form the low-viscosity sol, nearly in the shape of Newtonian fluid. On the contrary, if the concentration is elevated, it can form the high-viscosity sol, in the shape of non-Newtonian fluid.
● Synergy
It can produce a synergistic effect with such colloids as locust bean gum, konjac gum and xanthan gum so that it can improve the elasticity and water-holding capacity of the gel.
● Health Benefits
Carrageenan possesses the basic characteristics of soluble dietary fiber. The degraded carrageenan can form the soluble complex with fibrin in the body. Furthermore, it can be reduced to CO2、H2、biogas, and such short chain fatty acids as formic acid, acetic acid, and propanoic acid in the glycolysis by gut bacteria, so it can become the energy source of probiotics.