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info@dayanarman.com
021-44130192 ، 021-44130346 ، 021-44362477
There are several types of carrageenan: Lambda, Kappa, and Iota. They differ in chemical structure, properties, and applications, and their use depends on their gel-forming ability.
There are different methods for producing carrageenan. In the first method, carrageenan is obtained by extracting seaweed in an aqueous solution. In this method, the recovery process of carrageenan is difficult and production costs are higher than in the second method. In the second method, to wash away foreign substances from the seaweed and extract the carrageenan components, the seaweed is placed in an alkaline solution and water. In this process, pure carrageenan is obtained through alcoholic precipitation or gel methods, then concentrated. The remaining residue from this process is used in the production of semi-refined carrageenan or seaweed flour.
Various types of carrageenan are available and are classified into different groups based on their applications, such as kappa carrageenan, iota carrageenan, and lambda carrageenan.
Each of the mentioned carrageenans has different solubility and gelling properties.
Kappa carrageenan and iota carrageenan dissolve in hot water at temperatures above 70 °C.
The gel formed by kappa carrageenan is brittle, while the gel formed by iota carrageenan is more elastic and flexible.
Lambda carrageenan dissolves in cold water.
Carrageenan is used in the production of dairy products, various desserts, meat products, instant soups, jelly powders, and sauces.
The gelling and thickening properties of different carrageenans vary. For example, kappa and iota carrageenan form gels in solutions containing calcium salts, while this salt has no effect on lambda carrageenan.
Carrageenans are soluble in warm water. The thixotropic properties (meaning that this gel, after being stirred, can flow like a thick liquid, but if left to stand, gradually returns to a gel state) of lambda carrageenan make it suitable for use as a thickener, especially in the dairy industry, as it creates a non-gummy, creamy texture and gives the product a desirable mouthfeel.
Temperature is an important factor in determining which type of carrageenan is used in food systems. All types of carrageenan absorb water at high temperatures. Kappa and iota carrageenan gels, during cooling, begin to set between 40 and 60 °C (depending on the presence of cations in the system).
Carrageenan solutions lose their gel strength and viscosity at pH values below 3.4. This happens because intermolecular bonds between carrageenan chains begin to hydrolyze at low pH. The rate of hydrolysis increases with higher temperature and lower cation concentration. However, once the temperature is reduced below the gel-setting temperature, carrageenan retains its potassium sulfate bonds and hydrolysis does not occur. Therefore, in acidic products, carrageenan should be added just before the filling step to prevent degradation of its polymers.
The table below shows the approximate process time at different pH values for solutions containing 0.5% kappa carrageenan and 0.2% potassium, at which 25% of the initial gel strength is lost. It can be said that with every 0.5 unit decrease in pH, the time required to destroy the gel structure is reduced to one-third of the original time.
Solutions of kappa and iota carrageenan between 40 and 60 °C and at different cation concentrations form gels with various properties. Gels formed by carrageenans are thermoreversible, meaning that the melting temperature and the setting temperature are different. These gels are stable at room temperature, and by increasing the temperature to about 5–20 °C above the setting temperature, the gel melts
