Carrageenan is white or light brown particles or powder, odorless or slightly odorless, and has a slimy texture.
Carrageenan has the following four properties:
Gelability: The gelability of carrageenan is mainly related to its chemical composition, structure and molecular size. The formation of carrageenan gel is divided into four stages: when carrageenan is dissolved in hot water, the molecules become irregular curls; as the temperature drops, the molecules transform into spirals to form a single helix; when the temperature drops again, the molecules A double helix is formed, which is a three-dimensional network structure. At this time, solidification begins; when the temperature drops again, the double helix aggregates to form a gel.
Solubility: Carrageenan can be dissolved in warm water above 70℃. Generally, the higher the sulfate content, the easier it is to dissolve. Carrageenan first forms colloidal particles in water. Adding sucrose, glycerin, etc. can improve its dispersion or use a high-speed mixer to break the micelles to achieve a dispersing effect. In order to promote the dissolution of carrageenan, in food industry production, hot water above 80°C is generally used to dissolve and disperse it.
Acid stability: When the carrageenan solution has a pH value of 4.3, it will lose viscosity and gel strength when heated. This is due to the hydrolysis of carrageenan at low pH, which breaks the connection of 3,6-anhydro-D-galactose (HoffmannCh et al., 1996). At high temperatures and low cation concentrations, the degree of hydrolysis increases. However, once the temperature of the solution drops below the gel temperature, potassium ions can bind to the sulfate groups on the carrageenan, thus preventing hydrolysis from occurring.
Reactivity: The biggest difference between carrageenan and other water-soluble macromolecules is that it can react with proteins. The sulfate groups on the carrageenan molecule have a strong negative charge. Protein is an amphoteric substance. Below the isoelectric point, amino acids and carrageenan combine to produce precipitation because they hold opposite charges. Under conditions above the isoelectric point, the two hold the same charge, and multivalent cations serve as binding agents and Carrageenan combines to form a hydrophilic colloid. At the isoelectric point, multivalent cations act as binding agents and combine with carrageenan to form a precipitate.
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