1. Candy Crystallization Go to Slide Show mode and click the button

2. Heating phase Unsaturated solution (can dissolve more sugar in solution) End point cooking temperature

3. During the heating phase The concentration of sugar in the solution is increasing due to the evaporation of water The boiling point is increasing due to the colligative property of boiling point elevation, which says that as the concentration increases, the boiling point increases

4. Cooling phase Unsaturated solution End point cooking temperature Unsaturated solution Saturation point (solution has all the sugar it can dissolve) Supersaturated Solution (solution has more sugar than it should be able to hold) Room temperature

5. During the cooling phase There is no change in the sugar concentration But there is a decrease in temperature At some point (a unique combination of concentration and temperature) the solution will become saturated (has all the sugar it can dissolve at that temperature)

6. Supersaturation As the temperature drops below the saturation point, the solution becomes supersaturated (has more sugar than it should be able to dissolve) We can only make candy (i.e., recrystallize the sugar) when we are in the supersaturated region

7. Crystal formation But when should we induce crystal formation? At a relatively high temperature, or At a relatively low temperature? The answer depends on understanding about sugar crystal growth

8. Sugar crystal growth Sugar

9. Sugar crystal growth Sugar

10. Sugar crystal growth Sugar

11. Sugar crystal growth Sugar

12. Sugar crystal growth Sugar crystals grow by having sugar molecules deposited on their outer faces If we cool the syrup down to just a little above room temperature, the crystals will have less time to grow before they reach room temperature and stop growing

13. Inducing crystallization Large crystals, coarse Induce here Induce here Small crystals, smooth

14. Crystal size and texture This is important because in candy (and frozen desserts) crystal size = texture Large crystals = coarse, crunchy texture –No good Small crystals = smooth, velvety texture –This is what you want