What does amylase do?
Amylase enzyme converts starch into sugar.
Starch is a poly-saccharide, made of large number of glucose units. Glucose is a monosaccharide, the simplest form of sugar.
Starch is made up of two fractions, i.e. amylose and amylopectin. Each fraction is made up of large number of glucose units. The number of glucose units is much higher in amylopectin than in amylose.
Amylase enzyme breaks both these fractions into glucose units. Conversion of starch into sugars is test for the presence of amylase activity in plant tissue.
Starch gives blue color with iodine. Add plant tissue extract containing amylase enzyme in starch solution. The blue color disappears after sometime, indicating that starch has been converted into glucose.
Here is a video of an enzyme demonstration which demonstrates this process. The video shows how an enzyme (salivary amylase) present in our saliva (spit) can aid in the process of digestion by acting on starches present in the foods we eat.
video from: Noel Pauller
Hope this was helpful!