Do you know the differences between Agar and Carrageenan?

Agar and carrageenan have many things in common; both are hydrocolloids, both come from red algae, both are used as thickeners, and both are utilized in the food industry. But let’s look at the differences:

Although both come from red algae, each one comes from different species. As we have seen on other occasions, agar comes from the algae Gelidium and Gracilaria, while carrageenan is extracted from red algae of the species Euchema and Gigartina.

Unlike other hydrocolloids, the gelation of agar occurs through the formation of hydrogen bonds between agarose molecules, which generates a physical gel that does not require the participation of any other molecule. This marks one of the biggest differences with its “competitors” since most gums need other molecules to gel (they usually require the addition of salts or sugars). Carrageenan does need the help of external agents to gel, which can alter the taste, color, or smell of the food.

They have different gelling powers. Agar can form gels with concentrations much lower than 1.0% (even at levels of 0.1%), has a gelling power 5 to 8 times greater than other hydrocolloids, so much less product will be needed to produce the same effect.

Each produces different textures. Agar always achieves strong and brittle gels. As for carrageenan, there are 3 types: iota, kappa, and lambda, although the latter is used less in the food industry since it does not gel and has low viscosity. Iota carrageenan yields weak and elastic gels. Kappa produces strong and rigid gels. It is common to combine both types of carrageenan to achieve the desired gelatin texture.

We also find differences in how they behave with temperatures. The dissolution temperature of carrageenan depends on the type; kappa and iota dissolve from 70º while lambda is soluble in cold. Most agars are soluble at 100º except for low-solubility agars, which dissolve between 65 and 80º. A unique characteristic of agars is their high hysteresis (the difference between the gelling point and the melting point), which is at 50º.

If we analyze their synergies with other thickeners, we also find differences. Agar is a very noble ingredient that does not need synergies to carry out its function. While it has been seen that some types of agars can present synergies with some types of gums like guar gum and konjac gum. For its part, kappa carrageenan also does this, and additionally, it does so with konjac gum. Iota can be used with starch, and lambda has no synergies with other thickeners.

Another of the peculiarities we can talk about is the interaction with proteins; kappa carrageenan has a specific reaction with casein, and lambda has a strong interaction with proteins increased at acidic pH. For its part, agar does not react with proteins.

Finally, the caloric content of agar is really low, the lowest of all the thickeners used in the market.