Question: What is Jelly, a solid or a liquid?

Marcus Gallagher-Jones answered on 16 Mar 2012:

Well gelatin, the thing that makes up jelly and where it gets it’s name, is a solid without adding water. It’s a mixture of very hydrophillic (water loving) proteins. When you add water it becomes what is known as a colloid gel. In this state it’s actually both solid and liquid. What you have are many strands of protein that are bonded to each other and suspended in water. These bonds are very susceptible to breaking in water and so they are constantly breaking and reforming giving jelly it’s semi solid structure. The reality of this is that you have two separate phases, the solid cross-linked proteins and the liquid water surrounding them. In other words it’s actually both.