Gelatin

Type B gelatin is derived from beef bones and/or calf skins. Culinary gelatin, known as type A, is made primarily from pig skins. When dissolved, heated, and chilled, gelatin has the ability to turn a liquid into solid. This process is thermally reversible: The liquid will set at 68°F(20°C) and melt at 86°F(30°C). Unflavored gelatin is available in both powder and sheet (leaf) form. Either can be substituted in equal weights. When a recipe calls for powdered gelatin, the amount of liquid used to soften and dissolve the gelatin is generally specified. The liquid is usually cold water but might also be wine or milk, for example. The gelatin is sprinkled over the liquid and left for a few minutes to soften; it is then possible to heat the mixture in order to dissolve the granules.