Gelatin is used in molded desserts. The raw material for gelatin is the naturally occurring protein, collagen. When dissolved in hot water then cooled, it forms a jelly. Granulated gelatin is the most common form of unsweetened gelatin. Unsweetened gelatin is typically soaked in a cold liquid for 3-5 minutes before dissolving it. This softens and swells the granules so they will dissolve smoothly when heated. Leaf or sheet gelatin is also available, although not as common as the granulated form. Leaf gelatin requires a longer soaking time than granulated gelatin.
Many European recipes call for leaf gelatin. You can successfully substitute powdered gelatin for leaf gelatin in any recipe. One package (1 tablespoon) of powdered gelatin equals 4 sheets. One package of gelatin is enough to gel 2 cups of liquid.
For vegetarian version: Alternative choices include Agar-Agar, which is derived from seaweed. Agar-Agar is sold in noodle-like strands, in powdered form or in long blocks. Other options are arrowroot, guar gum, xanthan gum, pectin and kudzu.