Jell-O consists of four basic ingredients:
Gelatin, water, sugar or artificial sweetener and artificial flavors, food coloring
The gelatin in Jell-O is what lets you transform it into all sorts of different shapes. What exactly is gelatin? Gelatin is just a processed version of a structural protein called collagen that is found in many animals, including humans. Collagen actually makes up almost a third of all the protein in the human body. It is a big, fibrous molecule that makes skin, bones, and tendons both strong and somewhat elastic. As you get older, your body makes less collagen, and individual collagen fibers become crosslinked with each other. You might experience this as stiff joints (from less flexible tendons) or wrinkles (from loss of skin elasticity).
The gelatin you eat in Jell-O comes from the collagen in cow or pig bones, hooves, and connective tissues. To make gelatin, manufacturers grind up these various parts and pre-treat them with either a strong acid or a strong base to break down cellular structures and release proteins like collagen. After pre-treatment, the resulting mixture is boiled. During this process, the large collagen protein ends up being partially broken down, and the resulting product is called gelatin. The gelatin is easily extracted because it forms a layer on the surface of the boiling mixture.