1.When heating, we should stir the solution constantly. The water should be distilled water, if the water
contains cations, it will influence the dissolving of gellan gum. In that case , you have to use cations
containing water, you can add some chelating agent such as sodium citrate to get rid of these cations.
The adding amount of sodium citrate should be about 0.01~0.02%.
2.After gellan gum totally dissolved and the gellan gum solution became to cool down, then we need to add cations into gellan gum solution to make the solution form gel, gel forming temperature and the melting temperature is bound up with the concentration and category of cations. Generally speaking, you can use calcium ions, that is to say, you can add calcium chloride or calcium lactate. The adding amount of calcium chloride should be within 0.1%~0.2%, the calcium lactate adding amount should be within 0.25~0.3%. and pleased be noted that the calcium salt should also be prepared as solution firstly and then add into gellan gum solution, this will enable the cations dispense in solution evenly and form the gel better. .
3. gellan gum can form gel at very low concentration, at the concentration of 0.05%, gellan gum can form weak gel with the support of calcium salts, if the gellan gum concentration be 0.1%, the gel will be hard, if the gellan gum concentration be 0.5%, the gel will be very very good. So, you can get good gel if your used concentration is above 0.2%, and the calcium salts concentration should also be increased with the gum concentration improving.
But please be noted, the gellan gum ( the concentration below 1.0%) can not form gel if you do not add calcium salts in it. Because adding extra calcium salts is necessary for gellan gum to form gel. Generally speaking, if we using 0.5% gellan gum to form gel, firstly, we should heat the 0.5% gellan gum to above 90 degree with constantly stirring to make gellan gum dissolved totally, then we add about 0.04% calcium chloride or 0.08% calcium lactate into gellan gum solution, then after cooling, the very good gel will be formed.
Please also be noted, the calcium salts should be prepared into water solution firstly, then add into gellan gum hot solution, because gellan gum is so sensitive to calcium salts that if we add the calcium salts powder into gellan gum hot solution, the gellan gum solution will has locally gelling and then the gel will be very bad.
From above message, you can know, that calcium salts is necessary for gellan gum to form gel, if your customers just using gellan gum and do not use calcium salts, they can not get gel. For example, if they use 0.2% gellan gum, they should also add about 0.03% calcium chloride into gellan gum hot solution. Because of gellan gum so sensitive to calcium salts, so if we blend calcium salts powder into gellan gum powder, the gellan gum will be not dissolve in water, in this case, we must add chelating agents to chelate calcium salts and then by adding citric acid to releasing calcium ions from chelating agents to help gellan gum to form gel.