What's Jello(TM) made of?

Gelatin is made of hydrolyzed collagen, which is a polite way of saying 'partially decomposed protein extracted from cow and pig hides, hooves, bones, and connective tissue'. The protein in these materials is broken down by treatment with an alkaline solution and then extracted with hot water.

The protein in gelatin consists mostly of chains of amino acids (basic building block molecules for all proteins). The gelatin proteins are mostly made of glycine, proline, and hydroxyproline residues (but small quantities of other amino acids are also present). These acids allow the protein chains wrap into a stable three-stranded structure called a 'triple helix'. When the proteins are dissolved in hot water, the triple helices unwind into free protein chains. Cooling the solution again allows the triple helix to reform in some places, but not in others. The free protein chains form a tangled net, pinned together by partially reformed triple helices. The net has large pockets of of liquid trapped inside it. The trapped liquid gives gelatin its wiggle, but the protein net allows the gelatin to keep the shape it is molded into.

Author: Fred Senese senese@antoine.frostburg.edu

General Chemistry Online! What's Jello(TM) made of?