The title may be a bit of a misnomer: Really the first hydrocolloids that most people use tend to be flour, gelatin, and cornstarch. The difference is that when people first learn to cook, they don't realize how many of the ingredient they use are hydrocolloids, and so they never learn how to utilize them efficiently. Hydrocolloids are ingredients that control water in a recipe, binding with liquids to form gels or sols, colloidal suspensions.