Imaginative Teaching Resources & Inspirational Career Ideas from the Chilled Food Industry
Though schools might be going back soon we’re hoping our taste of food science has sparked your curiosity, and you’ll carry on exploring this fascinating subject that plays a major part in all our lives. Meanwhile, Morgan and Tilly again help with the latest batch of experiments. This time it’s all about sweet things….
To make this favourite treat you need 150ml of double cream, a tablespoon of icing or caster sugar, six tablespoons of salt, ice cubes, a drop of vanilla essence and a drop of food colouring. You’ll also need two resealable, zip top bags – on large and one small.
Prepare to do a bit of exercise! It will be worth it, we promise.
Put the cream in a small zip top food bag with icing sugar/ caster sugar and a drop of vanilla essence and a drop of food colouring. Zip it closed completely
Fill a larger zip top food bag half full of ice cubes and the salt. Put the smaller bag inside this large bag. Zip the larger bag up completely.
Keep the bags moving for ten minutes by throwing them (gently) between people or hand to hand or gently shake. Wear gloves to keep your hands warm!
After 10 minutes check on your smaller bag and you should have made ice cream!
Wow – now, the science behind it
Under normal circumstances, water freezes at 0C. But adding salt to the ice lowers the temperature by a few degrees. This means when salt is added to the ice in the outer bag, the ice (which is at 0C) is above its freezing point, so starts to melt. Melting needs energy which here comes from the cream mixture in the inner bag, heat energy is absorbed from cream making ice crystals form between the tiny fat molecules in the cream- making frozen ice cream!
You’ll find some more inspiration on the BBC Good Food website
Using water and salt you can supersize your sweets! All you need is a few jelly babies, salt, warm water, small bowl and glass.
Just put one jelly baby in a glass of water and another in a small bowl and put both in the fridge over night.
Look at how swollen and big the jelly baby in the water is! It’s grown!
Next take at glass of warm water and add a tablespoon of salt. Stir until it dissolves. Once the water is cool, add the swollen giant jelly baby. Leave for 2 hours and come back.
What’s happened? It will have reduced back to the original size of the jelly baby!
How did that happen?
Water molecules are constantly moving, jelly babies contain gelatine – which is a jelly like protein.
The gelatine structure allows water molecules to squeeze in between its molecules and join them – this is by a process called diffusion. The additional water molecules cause the jelly sweet to grow and swell. When we place that swollen jelly sweet into a salt water mixture , the salt particles diffuse into the gelatine and take the place of the water molecules, so the jelly baby loses the water molecules and shrinks to a smaller size.
This is very easy! Take a packet of Skittles, place them in a pattern on a white plate – we made a circle. Pour on some warm water till it touches and covers about a 1/3 of the Skittles. Wait and watch what happens
Skittles have a sugar coating which is coloured with food colouring. When we add warm water to the skittles the suger and food colouring start to dissolve in the warm water. As they are coated evenly they dissolve at the similar speeds and so give lanes of colour rather than mixing together