Physical properties of carrageenan
First, solution properties
All the carrageenan is soluble in hot water, but only ι and κ type sodium salts soluble in cold water. Usually the concentration of salt in food does not have an effect on λ-carrageenan; viscosity in cold water and milk, while high viscosity, if the solution is heated and cooled. Λ-carrageenan solution when pressurized forms or stirred pseudoplastic, or shear-thinning solution. These solutions are often used to thicken, especially in dairy products, and to provide a non-sticky, creamy texture of the system.
Temperature is an important factor to determine which types of carrageenan is used in the food system. All the hydrate applies to high temperatures and Kappa carrageenan and ι-especially the low viscosity of the liquid. When cooled, the carrageenan in 40-70 between a series of gel type depends on the type of carrageenan and yang Ion concentrations.
Second, acid stability
When the carrageenan solution at PH 4.3, heat-treated will lose viscosity and gel strength. This is because the carrageenan hydrolysis occurs at low PH values, disconnected from 3,6--anhydro-d-Galactose (Hoffmann 1996). At high temperature and low cation concentrations, degree of hydrolysis increases. However, once the temperature of the solution below gelling temperature, potassium ions combine with sulfate groups on carrageenan, this will prevent the occurrence of hydrolysis.
In order to minimize the effects of hydrolysis, it is recommended that, in the case of possible, carrageenan should be dealt with under neutral conditions and acid should be added immediately in front of a food store and filling. In acidic foods, carrageenan should be added before the end of production in order to avoid excessive decomposition of the polymer.