Hydrocolloids — gelling agents derived from seaweed, seeds, bacterial fermentation, and other sources — each produce gels with properties that gelatin and starch cannot achieve: gels that set hot and melt cold, gels that remain stable at high temperatures, gels that can be blended into a fluid that re-sets, and gels so firm they can be sliced, cooked, and fried. Modernist Cuisine's systematic treatment of hydrocolloids gave professional kitchens a vocabulary for texture that didn't previously exist.
Decisive moment: For hydrocolloid gels: the bloom or activation. Each hydrocolloid must be fully hydrated and dissolved before its gelling properties activate. Undissolved agar lumps produce a grainy gel; undissolved xanthan produces lumps. The technique of dispersing hydrocolloids in a fat or cold liquid before heating is the professional method.
Modernist Cuisine Vol. 4