Collagen is the main ingredient in gelatin. Collagen is a protein that is prevalent throughout the bodies of many animals, including humans, in the bones, tendons, skin and connective tissues. Collagen in gelatin can come from the bones of cows or pigs, or more commonly, pig skin.
Manufacturers process the collagen with a strong acid or base and then boil it. They then cut and dry the resulting gel and grind it into a powder.
Other types of gelatin can include other ingredients, such as agar-agar, kuzu, xantham gum and guar gum. These types of gelatin are plant-based and come from sources such as seaweed, arrowroot and beans.