To obtain the maximum functionality from carrageenan, it is important to ensure its dispersion before its hydration. Lumps formation must be avoided. To this aim, it is recommended to blend carrageenan with other ingredients in powder from the application formula, as skimmed milk powder, sugar, salt, among others. This blend is added to the water or to the milk, slowly and under constant agitation.
After it is disolved and during cooling Kappa I, Kappa II and Iota carrageenans form a molecular structure of double helix type, which alings itself to form a three-dimensional network reinforced by the presence of certain cations such as potassium and calcium, forming a gel at ambient temperature.
There is a high reactivity in the carrageenans, specially those of type Kappa II and Kappa I in dairy systems, obtaining firm gels at very low concentrations. This characteristic is due to the direct interaction between the carrageenan and K-casein.
The interaction is dependent on the pH, since K-casein above its iso-electric point (pI) has negative electric charge and below this point, positive electric charge. Therefore, it is possible that at neutral pH, the interaction is given thanks to the formation of calcium bridges while in at moderate acid pH, is direct by opposed electric charge. Besides, hydrogen bridges formation is possible.
Kappa I and Kappa II carrageenans type interact with potassium and calcium salts increasing the gel forming temperature, the firmness and the melting temperature of the gel.
Poly-phosphates and sodium or potassium citrates facilitate the dispersion of carrageenans in aqueous medium or in milk, but not their hydration, that is revealed with the reduction of viscosity of the dispersion. Even though these salts kidnap di-valent ions, they introduce sodium salts that strongly compete for the water available in the medium, causing less hydration of carrgeenan and therefore a lower viscosity.
Kappa I and Kappa II carrageenans have synergy with certain galactomannans and glucomannans as locust bean gum (LBG) and Konjac gum that reinforce the gel strength, reducing syneresis, giving more elastic gels, with interesting savings, since it is possible to decrease the use dosage of the gelling system.
Iota carrageenan has synergy with starch, producing an increase of viscosity and consistency in both aqueous or milk systems; allowing to reduce the employment of starch in the formula, enhancing the palatability, flavor release of the end product, among other benefits.
Carrageenan solutions, the same as other hydrocolloids, are stable to a neutral or slightly acid pH.
Exposure to acid pH, combined with high temperatures and long time causes carrageenan hydrolysis with loss of its capacity to form gels. Due to this reason is advisable to work at pH of value higher than 3.8, forming a buffer system by means of the addition of sodium or potassium citrate.
In these low pH systems such as water desserts or fruit preparations, it is recommended to incorporate the acid at the latest step possible in the process and to cool the system quickly in order to obtain the best carrageenan functionality.