Third and Fourth Class
Pineapple Jelly – Will it Wibble Wobble Or Will It Not ?
This pineapple jelly experiment which was carried out by 3rd and 4th class is a brilliant example of how students can work scientifically while understanding core concepts of the changing states of matter introducing them to the concept of enzymes and molecules.
Materials Needed
- Hot water
- Packet of Jelly
- Fresh pineapple – 2 rings
- Tinned pineapple – 2 rings Equipment
- Chopping board
- Measuring Jug
- Two glasses
- Spoon
- Scissors / Knife
Steps Taken
1 Dissolve the Packet jelly with boiling water.
2 Roughly chop the fresh and tinned pineapple into cubes
3 Place the fresh pineapple in glass A , the tinned pineapple in glass B and pour over the liquid jelly. Fill up to the top .
4 Set in fridge overnight.
What Happened?
We dropped a coin into Glass A and Glass B.
The coin sinks to the bottom of the jelly with the fresh pineapple because it hasn’t set and is very watery.
The coin sits on top of the jelly made from tinned pineapple, as it has set.
Why didn’t the jelly with the fresh pineapple set?
Jelly contains gelatin, which is made out of an animal protein, collagen.
When you add hot liquid to gelatin, invisible long chains of protein form, like “spaghetti”.
Water gets trapped in the middle of these long chains, and the liquid sets because the protein molecules tangle up as they cool down trapping the water to make a wibbly wobbly jelly.
Bromelain is an enzyme found in pineapples. It is also used as a meat tenderiser ( comes in a powdered form).
This enzymes chops up and breakdown protein molecules, making them smaller, so they can’t tangle up. This stops the jelly from setting.
The jelly with the tinned pineapple has set because the tinned pineapple has been heated to destroy any bacteria growing in the tin but the high heat also destroys the enzyme Bromelain so there is none left in it.
Did You Know?
Some people are so sensitive to this enzyme it makes their lips and tongue tingle. This is because the bromelain is working to tenderise your tongue. But don’t worry – you would have to eat lots and lots of pineapples at the same time for this to happen so small amounts are harmless!
