What it does
Native collagen swells and binds water, and on heating it converts to gelatin, which sets into a gel on cooling and melts again on warming. That melting behaviour is distinctive: it is the only common protein gel that reverses on heating, and it gives the mouthfeel described as melting rather than firm.
Where it works
Cooked and emulsified meat products, where it adds bind and a succulent bite. Jellied products and aspics, where the reversible gel is the point. Also as a yield aid in whole muscle.
Where it does not
It is poor at stabilising fat compared with myofibrillar or soy protein, so it is not an emulsifier substitute. The gel melts at body temperature, which is wrong wherever a product must hold structure when warm. It also excludes vegetarian, vegan and several religious positionings.
What it interacts with
Heat, which converts it. Other proteins, beside which it is usually used rather than instead of.
