This demonstration shows that enzymes in pineapple, namely bromelase, catalyse the digestion of the gelatine in the jelly, essentially eating away at it.
Equipment typically required (per demo):
Two bowls of jelly need to be made up in advance of this lesson or one big bowl that will allow both pineapple rings to be placed on the surface leaving a gap between them. Any flavour or colour of jelly is suitable for this demonstration as long as it has been left in a fridge long enough to set completely.
- Two bowls (or one large bowl) of set jelly
- Fresh pineapple ring
- Tinned pineapple ring
A ring of pineapple is taken from the tin and placed on the surface of the jelly in one of the bowls. A ring is cut from the fresh pineapple and placed on the other jelly. Over the course of around 15 minutes, the fresh jelly ring should have noticeably sunk into the jelly whereas the tinned variety should remain on the surface.
The enzymes in the fresh pineapple eat away the protein (gelatin) in the jelly. The enzymes in the tinned pineapple have been destroyed by the heat treatment involved in the manufacturing process. Because of this, the tinned ring should sit on top of the jelly.
Estimated technician preparation time: 6 hours minimum (for the jelly to set).