We enjoy having jelly for dessert. It is not only a colourful dessert, the way jelly wobbles makes us enjoy playing with it while we eat. Why jelly wobbles all boils down to chemistry.
What is jelly made of?
Jelly comes in powdered crystals that you add to hot water. But what does this jelly powder contain? Jelly is a processed form of protein called collagen. This is a protein found in all animals. It even makes up one-third of the proteins found in our body. It is a highly structured protein, which gives us strength, protection and flexibility.
These chains of collagen protein stick together giving jelly its wobbly nature.
These chains of collagen protein stick together. They are bound to each other in a triple helix of hydrogen bonds. This gives jelly its wobbly nature. When you heat jelly, these protein chains move freely and do not stick to each other, as the jelly cools down the protein chains get entangled in a loose network. This is why jelly is more liquid like when it is hot and wobbly when it sets.
Have you ever heard about the pineapple and jelly experiment?
Have you ever noticed a warning message on the back of jelly packets, warning you not to add pineapple in jelly? If you pay no heed and do add pineapple, you will notice the jelly slowly returns to its liquid state!
The reason for this is simple; pineapples contain an enzyme called bromelain, which break down proteins. Since protein is what jelly is made of, the bromelain in the pineapples break the protein chains, causing the jelly to return to its liquid state.