Starch is a carbohydrate found in potatoes, rice, maize, wheat, corn and other grains. You might want to convert starch to sugar to brew your own beer, as the sugar can be transformed into ethanol by a process of fermentation. Wheat and corn are the most commonly used ingredients for transforming starch into sugar.
Convert Starch to Sugar
Grind either wheat or corn kernels in the hammermill.
Transfer the ground grain into a container suitable for cooking and mix it with twice as much water.
Heat up the mixture to roughly 150 to 168 degrees Fahrenheit. Leave the mixture at this temperature for up to two hours. During this time, enzymes in the grain convert the starch to sugar.
Test Your Mixture
Take a sample of the mashed grain and set it aside.
Add a drop of iodine to the mixture.
Watch the mixture for changes in color. If the iodine turns clear or yellow, all the starch has been converted to sugar. If it stays a dark color, the mixture needs to remain at the above temperature for a longer time.
TL;DR (Too Long; Didn't Read)
If your grain is very dry, soak it in water for a day before heating it.
If while steaming the mixture becomes a thick, stiff paste, adding a small amount of malt can soften it.