Cations – As the absolute concentration of cations increases:
- dispersion improves
- temperature at which carrageenan goes into solution increases
- gelling temperature increases
- remelt temperature increases
Potassium and calcium ions are essential for effective carrageenan gelation. Increasing the level of potassium ions increases the strength of the resulting gel. Figure 8 illustrates the relative increase in gel strength when the level of potassium (% KCl) is increased.
Temperature – As discussed earlier, carrageenan water gels are thermally reversible. The gels can be subjected to repeated heat/cool cycles with very little effect on the resulting gel structure (at neutral pH).
The set and melt temperatures of carrageenan gels are dependent on cation concentration. Increasing the level of calcium or potassium in an aqueous solution will result in increased gelling temperatures. See Figure 9 (below).
This allows formulators to regulate gelling and melting temperatures to accommodate their processing parameters . Most other hydrocolloids do not offer this flexibility.
Sugars – High levels of sugars, a common component in many food gels, reduce the solubility of carrageenan. Carrageenan should be dissolved in available water if the sugar concentration of the food system is higher than 50% of the finished product.
Synergism with Other Gums – Kappa carrageenan is synergistic with locust bean gum and konjac flour. The interaction significantly increases gel strength, improves moisture binding capabilities and modifies gel texture to be more elastic and resilient, as shown in Figure 10 (above).
Synergism with Starch – Iota carrageenan increases the viscosity of starch systems by as much as 10 times the viscosity of the starch alone. When kappa carrageenan is added to starch systems no increase is noted.
Figure 11 compares the effects of shear on a starchonly system with starch/iota carrageenan and starch/kappa carrageenan systems. The starch system exhibits a loss in its viscosity when subjected to shear. The presence of 0.5% kappa or iota carrageenan allows a starch system to recover its pre-shear viscosity.
Carrageenan may be useful in altering the textural, mouthfeel and processing properties of a starch system. The increased viscosity will allow processors to reduce the overall starch content, often by as much as 35-40%, and improve the texture and flavor release of the finished product.
Acidulants or pH– Solutions and gels that are formed with carrageenan are stable at room and refrigerated temperatures. At high temperatures, carrageenan solutions that contain acidulants exhibit some loss in viscosity and potential gel strength. See Figure 12.
In low pH systems, it is recommended that the acidulant be added at the last step of processing, or just prior to filling into containers.