National Chemistry Week - Experiments - Making Sponge Toffee
Objective:
Household cooking involves chemistry. Here's a chemistry experiment in which the product is edible. What is the purpose of the sodium bicarbonate? To help answer this question think of what happens when you make baking soda biscuits.
Materials:
750 mL sucrose
333 mL corn syrup
1.25 mL sodium chloride (salt)
5 mL unflavoured gelatin
15 mL col H20
15 mL sodium bicarbonate (baking soda)
9 inch cake pan
large sauce pan
wooden spoon
candy thermometer
knife
wax paper
Procedure
Oil the cake pan.
Combine sucrose, corn syrup, and sodium chloride in the sauce pan and stir over medium heat until the sucrose is dissolved. Stir occasionally.
Soak the gelatin in cold H20
When mixture is 416 K (143° C/ 290° F) immediately add the sodium bicarbonate and gelatin. Stir rapidly.
Remove from heat and stir until the consistency is thick and the colour is golden (1 - 1.5 min).
Pour the contents into the cake pan and cool thoroughly.
Loosen the toffee from the sides of the pan and remove it.
