Gelatin is protein product produced by partial hydrolysis of collagen a protein extracted from animal by-products, such as skin, bones, cartilage, ligaments, etc. Gelatin can be obtained from all animals, in practice gelatin is mainly produced from cattle or pork. Special halal and kosher gelatin is available in many countries and/or specialised shops.

Gelatin is used as a thickener, as it forms strong gels. Gelatin is the only non-carbohydrate (polysaccharide) thickening agent used in food. Unlike most polysaccharide gelling agents, gelatin gel formation does not require the presence of other reagents such as sugars, salts or minerals (such as calcium) and is not dependent on the pH (acidity).

Gelatin is relatively insoluble in cold water but hydrates readily in hot water. When added to cold water gelatin granules swell into particles absorbing 5-10 times their weight in water. Raising the temperature above 40º C dissolves the swollen gelatin particles forming a solution, which gels upon cooling. The rate of solubility is affected by factors such as temperature, concentration and particle size. Gelatin is insoluble in alcohol and most other organic solvents.

The rigidity of gelatin gels increases with time as the gel matures reaching an equilibrium, approximately after 18 hours of maturation.

Gelatins are graded and marketed on ‘bloom' strength which is a measurement of the gel strength determined according to international standards and methodology.

Gelatine was previously considered an additive in the EU law and was numbered E441. Nowadays it is considered an ingredient and should be listed by name only.