What You'll Need
- Hot water
- Packet of Jelly
- Fresh pineapple – 2 rings
- Tinned pineapple – 2 rings
- Chopping board
- Measuring Jug
- Two glasses
How to Do It
Prepare the Experiment
- 1Dissolve the Packet jelly with boiling water.
- 2Roughly chop the fresh and tinned pineapple into cubes
- 3Place the fresh pineapple in glass A , the tinned pineapple in glass B and pour over the liquid jelly. Fill up to the top .
- 4Set in fridge overnight.
- 1Drop a coin into Glass A and Glass B. Observe and record the results.
What I Observed
- 1The coin sinks to the bottom the jelly with the fresh pineapple - Glass A: The jelly with the fresh pineapple hasn’t set and is very watery.
Glass B: The jelly made from tinned pineapple, the coin sits on top of the jelly in the glass with the tinned pineapple.
The jelly made with the tinned pineapple has set.
Quiz Time: 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). 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!
- This enzymes is a proteases which means it 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 also destroys the enzyme Bromelain so there is none left in it.