Edible gelatin is a collagen protein extracted from fresh animal hides and bones through a series of processes, including sorting, defatting, rinsing, neutralization, and hydrolysis. It comes in the form of pale, colorless to pale yellow flakes or granules, is odorless and tasteless, and contains 18 essential amino acids. It is widely used in the food industry as an excipient, thickener, and clarifier for beer.
Functional Properties of Edible Gelatin
- Physical Properties
Edible gelatin is white or light yellowish-brown, translucent, slightly shiny flakes or powder. It is virtually odorless and tasteless. It is insoluble in cold water but can absorb five times its volume of cold water, swelling and softening. It dissolves in hot water and forms a gel upon cooling. It is soluble in aqueous solutions of polyols such as acetic acid, glycerol, and propylene glycol. It is insoluble in ethanol, ether, chloroform, and most other non-polar organic solvents.
- Chemical Properties
Edible gelatin has weaker coagulation power than agar and will not gel at concentrations below 5%. It typically forms a gel at a 10% to 15% solution. The gelation temperature varies depending on factors such as concentration, the types of coexisting salts, and the pH of the solution. The difference between the dissolution temperature and the solidification temperature is very small: it dissolves at approximately 30°C and solidifies at 20-25°C. The gel is softer than agar, more elastic, and has a softer texture. Prolonged boiling of its aqueous solution causes decomposition and changes in its properties. Upon cooling, it no longer forms a gel. Further heating converts it into protein and peptone. Gelatin solutions, when exposed to formaldehyde, become irreversibly insoluble in water.