You can’t really eat this experiment but it shows the difference between dextrinisation and caramelisation.
A piece of white bread
A teaspoon of icing sugar mixed with a tiny, tiny amount of water
Either a grill or a blow torch – which is more fun!
A baking tray
What to do
Put the slice of bread on a baking tray and drop a blob of the icing mixture on the middle.
Grill the bread and sugar or burn with a blow torch until the bread changes colour.
Watch the changes in the bread – dextrinisation – and the sugar – caramelisation.
Don’t eat the toast until the caramelised sugar is cool!
The toast should taste slightly sweet – dextrin – and the sugar will taste like toffee.
The science bit
When dry starch is heated – like the flour in bread, a brown substance called dextrin is formed.
The food goes through a chemical reaction where starch breaks down into dextrin which is a slightly sweet, brown substance.
Caramelisation is the process of cooking sugar until it turns brown. All sugars caramelise.
Creme brulee is made by caramelising the top layer of sugar on a custard.