What two reasons could explain why starches differ from each other in properties (gel strength, clarity, fl avor, stability, etc.)? Why should cornstarch not be used to thicken pastry cream that will...

What two reasons could explain why starches differ from each other in properties (gel strength, clarity, fl avor, stability, etc.)?

Why should cornstarch not be used to thicken pastry cream that will be frozen? What starch is the best choice to use instead?