You might want to sit down for this. Gelatin is a tasteless, odorless, almost colorless mixture of proteins that dissolves in hot water, but becomes a jelly when cooled, holding the water in a rubbery suspension. It is used in the preparation of many different foods - the basis for Jell-o, for instance, but also to dress up aspics and pâtés, and to give structure to creamy desserts, such as some mousses, cheesecakes, and commercial ice cream. OK, perhaps you didn't need to sit down for that. But where does gelatin come from?

It is derived from collagen found in the bones, cartilage, connective tissue, and skin of animals, traditionally cows. Most commercially produced gelatin nowadays is produced from pig skin. If you have ever roasted a chicken or ham, you made your own gelatin. The juices in the bottom of the pan contain gelatin rendered from the collagen, and if you put the roasting pan in the refrigerator, you'll find some of the juice setting into a gel.

Every grocery store sells animal-based gelatin (the leading brand in this country is Knox, in orange and white boxes).