Potato flakes

Oh I love potato bread! But to the question - starch would give similar textures, but different tastes. Personally, the allure of the bread is the taste, so i wouldn't want to change that. That said, try it and see what happens. I'll even keep an eye on this thread to see the results. And it's too shabby out to hit golf balls, I think I'm gonna make a loaf of potato bread! Thanks, and Enjoy! 

of a cup of flakes but sure it is lighter than a cup of potato starch.  The equivalence will be the tricky part.

Mashed potatoes usually have some of the starch removed often by peeling, cutting up and cooking in water.  The cooking water then contains starch and is separated from the cooked potatoes before mashing.  This is done to prevent mashed potatoes ending in a gooey mass.  To make  flakes, mash potatoes are then dried into flakes to rehydrate later.

 I think you will need far less potato starch than flakes.  You may also have to adjust the recipe water.

Other solutions:

Use potato water either by grating the raw potatoes and soaking in water (letting the starch settle out) or in using potato cooking water from boiled potatoes as the liquid in your recipe.  Three medium to large grated potatoes soaked will yield (I think) roughly a rounded tablespoon of wet potato starch (after settling and slowly pouring off the water) if that gives you any idea of where to start.  

In other words, start with less than one level tablespoon and see what it does using slightly less water in the recipe.  You might want to stir the starch into part of the recipe water before adding to the flour.

Or boil a potato without the skins and cut into quarters or cubes and just enough water to cover until done, crush the potato into the water and use as part of the recipe liquids.  (Can include the skins if you have tasty ones or early potatoes)

Have fun!  

I've always wanted to try eliminating the recipe salt and add crushed potato chips to dough.  The result would be a mild version of the chips?