Carrageenans are natural extracts taken from red seaweed. There are several types and one of the most popular is iota carrageenan.
Iota carrageenan can be used to thicken liquids and stabilize emulsions or foams. It's also very adept at creating gels. Iota carrageenan works best with dairy products but can be used with a variety of liquids.
You can buy iota carrageenan several places. We highly recommend ModernistPantry.com, they have great service and are really good to work with (because of this, we do have an affiliate relationship with them), and they also sell the Texturas brand. You can also find iota carrageenan at WillPowder and get larger quantities and bundles at ForTheGourmet.com.
The firmness of an iota carrageenan gel is determined by the amount of iota carrageenan used to create it. The more iota carrageenan used, the firmer the gel will become. Usually a percent of 0.75% to 1.5% iota carrageenan is used for gels. For dairy gels, 0.4% to 1.5% iota carrageenan is often used.
Iota carrageenan fluid gels are typically made out of gels created with a 0.1% to 1.0% ratio. Iota carrageenan foams use 0.2% to 1.0% gels. To thicken dairy liquids a ratio of 0.02% to 0.04% is often used.
In order for iota carrageenan to be used effectively it has to be properly dispersed and hydrated.
Iota carrageenan is best dispersed in cool liquids. This will prevent hydration until the liquid is heated. An immersion blender or standing blender is the preferred tool to disperse the iota carrageenan.
In order for iota carrageenan to hydrate properly it has to be brought above 70°C / 158°F. Iota carrageenan does not hydrate well with sugar and so sugar should be added after the hydration process is completed.
The simplest application of iota carrageenan is the thickening of dairy products. Adding iota carrageenan to dairy based drinks or sauces is a great way to add thickness and improve mouthfeel.
To thicken a dairy liquid first disperse the iota carrageenan into the cold liquid using an immersion or standing blender. Then heat the liquid above 70°C / 158°F so it can hydrate. Let the liquid cool and it will thicken.
The amount of iota carrageenan used to thicken liquids really depends on how thick you want the liquid to become. Usually, a ratio of 0.02% to 0.04% is used. Anything much higher than that will begin to set as a gel. For greater thickening you can make a fluid gel as described below.
Creating a gel with iota carrageenan results in an elastic gel. The firmness of the gel will depend on how much iota carrageenan is used. You can make the gel more brittle by adding kappa carrageenan.
To gel, the liquid must contain calcium that is free to bind with the iota carrageenan. If the base ingredient lacks calcium it can be added in the form of calcium salts like calcium lactate or calcium chloride.
Making an iota carrageenan gel is similar to creating other gels. Make sure the liquid you are gelling is cold then use a standing or immersion blender to disperse the iota carrageenan into it. Heat the liquid above 70°C / 158°F then pour into molds and let cool.
The gel will set at 40-70°C / 104-158°F, depending on the amount of calcium ions present. It will melt about 5-10°C / 9-18°F above the setting temperature.
Iota carrageenan gels will usually use a ratio of 0.4% to 1.5% for dairy gels. For non-dairy gels, a 0.75% to 1.5% ratio is pretty standard. If you want a more brittle gel you can replace some of the iota carrageenan with kappa carrageenan. The more kappa carrageenan is added, the more brittle the final gel will be.
Iota carrageenan fluid gels are often used as cream sauces or puddings. They are made by blending an iota carrageenan gel until it is a smooth puree. Using an immersion blender or standing blender to puree the gel works well.
In general a ratio of 0.1% to 1% iota carrageenan will result in a fluid gel ranging from a thin cream sauce to pudding like. You can thicken the fluid gel by adding some xanthan gum or thin it out by adding water or another liquid when you are pureeing it.
Iota carrageenan foams are made from iota carrageenan fluid gels that are dispensed from a whipping siphon. These foams are thick, fine foams that are very dense.
For iota carrageenan foams, the more iota carrageenan you use the denser the resulting foam will be. The foams will range from light foams starting around 0.2% up to denser foams at 1.0%.