Blooming Gelatin

Unflavored dry gelatin must be rehydrated before it is used. This is called blooming. When the gelatin comes into contact with cool water or a water-based liquid, it absorbs the liquid and expands. Thus, when you rehydrate gelatin you are said to bloom it.

After blooming, the gelatin is usually mixed with additional liquid that is warm enough to completely dissolve it. When this liquid is then chilled, the protein gel forms, and the liquid is said to have set. The degree of firmness to which the liquid gels is called its set.