Agar is another example of a phycocolloid (a colloid extracted from seaweed). It was actually discovered years before the other 2 phycocolloids (carrageenan, and alginate). Agar is a very versatile gelling agent. It forms thermo-reversible gels that gel when cooled and melt upon reheating. When using agar it is good to know that even the smallest concentrations (.2%) can create a stable gel. When used as your sole gelling agent agar forms brittle gels with a very short texture. I have used agar for a variety of different applications in the pastry kitchen. One of the biggest uses that I have come across is "fluid gels". Basically a fluid gel is a gel that has been set and then reblended to form a "thickened" sauce or puree. Agar can also be used in conjuction with other hydrocolloids to form a wide range of textures. One of the most common synergies is the agar/ locust bean gum (LBG) concentration. By adding a small ammount of LBG to your recipe you can vastly change the outcome of the gel. The gel strength will be increased, and the texture of the resulting gel will become more elastic. This can provide a better mouthfeel when eating the gel. Agar gels also have the ability to become heat stable to a point. Gels made using agar can be held at temperatures up to ~80 C before remelting. This can be a desired property if your trying to make a "hot gel". Below is a basic fluid gel recipe using agar.
Fluid Gel350 liquid
1.5 agar
.5 ascorbic acid
1.5 gelatin
tt sugar
MethodBloom gelatin in ice water
Sheer agar, ascorbic, and sugar into liquid
Bring the liquid to a boil while whisking
Simmer for 1 minute
Take off heat, and add bloomed gelatin
Poor out and leave to set
Vitaprep the gel smooth
Pass
Enjoy