Gelatin. Cross-links. Supermolecules. And the science secrets of the wiggle jiggle.
When the collagen in meat dissolves into gelatin during braising or stewing, the gelatin makes the meat juicy and tender because it can hold many times its weight in water and has a gel-like structure.
Gelatin is also used to make jelly (and gummy bears). In this case, the gelatin has cooled down and set into a wobbly wiggling jiggling solid.
Why does this happen?
When gelatin cools down, the individual protein strands in the gelatin do not have any real form or crystalline structure (i.e. amorphous, similar to a pile of tangled noodles). As the temperature drops, they try to form cross-links with each other.
Cross-links are covalent and ionic bonds that link one polymer chain – such as each of the gelatin protein strands – to another. By doing so, they hope to reverse the denaturation and restore (also called renature) the triple-stranded helix structure (see above) that was in the original collagen.
Unfortunately, collagen denturation is irreversible. These cross-links do not form along the entire length of the gelatin strands so the reversion is not complete. Instead, the cross-links only occur at junctions spread out along the strands, forming giant molecules known as “supermolecules”.
The effect is the molecular structure of gelatin that has set into jelly looks more like a net. The supermolecules form molecular structure that is similar to a 3D net stretched across the entire jelly.
Within this 3D net are trapped water molecules. This is because the gelatin in jelly is very hygroscopic i.e. it can attract and hold onto water molecules readily like how paint brushes and paper draw up water.
It is this 3D net filled with water that gives jelly the wiggle jiggle. When we push on one end of the jelly, because it is one connected supermolecular net, the energy is transmitted to the other end. At the same time, because it is filled with water, it wobbles as it is not completely solid.
In that respect, this 3D net filled with water that is jelly would be akin to a balloon filled with water. Anyone who has tried to throw or catch a balloon filled with water will remember how it wiggles, jiggles, and wobbles as we try to hold on to it.
The balloon’s rubber exterior is like the 3D net (in fact, rubber is also a “supermolecule”) and the water inside gives it the bounce. There are differences in this analogy of course, but it’s a good example to illustrate the science we have just covered in this 1-Minute NomNom.
Have a jelly good time learning new things by liking me to discover more. All you need is a minute a day to explore the world’s marvels through the phenomenon of food!
photos: in order – depositphotos/Rawlik; coolfonk; mamopictures; nito103