If iodine were not available, how would you determine whether tarch hydrolysis had occurred?

Answer 1

There are products available that combine starch with a dye. After starch hydrolysis, the dye is cleaved from the starch, releasing it into solution. The solution becomes blue from the dye. If no hydrolysis, the dye remains attached to the starch and the solution is clear with just a colored pellet.
One such product is "Phadebas"

Answer 2

Measure the increase in the product, eg glucose or other sugars, either by tasting it (assuming non-poisionous ingredients have been used), or by biochemical analysis.