Via “Chowhound‘s” Food Media
Liz Hickok makes sculptures of San Francisco in jello. This is Telegraph Hill shaking and wobbling.
Christine Joly-Duhamel and colleagues in 2002 * suggest that the basis of jello (an all gelatin gel) elasticity is the extent and size of the triple helix regions – and therefore I infer, not the entropic contribution of the highly flexible coils separating them. An entropic contribution would come from the coiled regions being straightened out on deformation. Straightening the coils would make them more ordered, thus decreasing entropy, and so there would be a restorative force “seeking” to return to the higher entropy (more disordered) state. Although never purely entropic, polypeptide gels have been considered more entropic than enthalpic (Rheology of fluid and semisolid foods – M. A. Rao page 326), but Joly-Duhamel’s model suggests a more enthalpic type gel for gelatin than was thought previously. Enthalpic restorative forces in gel elasticity come from the energetics of bending and otherwise straining bonds in relatively stiff chains – a model considered valid for many polysaccharide gels.
*All Gelatin Networks: 2. The Master Curve for Elasticity. Christine Joly-Duhamel, Dominique Hellio, Armand Ajdari, and Madeleine Djabourov. Langmuir, 2002, 18 (19), 7158-7166• DOI: 10.1021/la020190m • Publication Date (Web): 27 July 2002