Gelatin Structure

Gelatin is a natural polymer as it is animal protein that is produced from the partial hydrolysis of collagen, the collagen can be extracted with very dilute acid from animal skins and bones. The structure of gelatin consists of several amino acids most of which are glycine residues⁹.

In order to produce gelatin, collagen must undergo denaturation causing it to lose its original structure, the helixes that form the fibres of collagen lose their confirmation during heating but when cooling they partially recover their structure⁹. Because of this water is trapped inside the chains, therefore a gel like structure is formed. The structure of gelatin is different to that of collagen as the helixes in gelatin are only partially formed⁹. During gelation the structure of gelatin changes, as single α-chains bond together, or single chains create loop and both sides bond together, triple strand structure can be formed by 3 α-chains bonding together or by 2 chains bonding together whilst one of the chains forms a loop, also a single α-chain can form a triple strand if the chain forms 2 loops. These structures are reversible but also stable, which means that they are stabilized by weak bonds⁹.

Hydrogen bonds stabilize the double and triple stranded helixes, the hydrogen atoms used in the hydrogen bonds are found inside the helix structure on the glycine units which are located every 3 amino acids along the α-chain. These glycine hydrogen atoms form weak hydrogen bonds with the oxygen atoms of the carboxyl group. The solvent water molecules also have a role to play in the gelatin network, as gelatin in heavy water (D₂O deuterium oxide) forms hydrogen bonds between -NH group of one amino acid and the -CO group of another amino acid on another chain. These bonds help stabilize the structure of gelatin⁹.