I do not know about your recipe and dough thickness before baking...but
It is likely You are overbaking your pitas... You should be baking it at less time at higher temperature, unfortunately that is unattainable with home oven. therefore the likely remedy will be to sheet it a little bit thicker and bake longer at that temperature; add slightly more fat, add some milk in the liquid so thati t will brown faster and there is no need to bake it longer when the dough starts to colour in the oven.. A 500 degree F is very low for baking a good quality authentic pita bread. That is equivalent to roughly 260 degree C. meanwhile the authentic pita breads are baked at 400-600 degree C(
750 to 1112 degree F.) a commericial pita bread is baked according to its thickness. And commercial recipes are rather lean much like the french bread. It can be simply stated in simpliest mathematical term in baking pocket bread. Baking temperature is inversely proportional to its thickness, but the baking time is directly proportional to it( dough thickness) . Thinner pitas are baked at higher temperature at less time; thicker pitas are baked at lower temperature at longer time. The typical commerical baking conditions corresponds with its thickness: a dough sheeted on a 1 mm roll gap ( comes out about 1.2 to 1.4mm after contraction during sheeting )of the sheeting machines is baked at 600 deg C for 21 seconds.
1.1-1.2mm gap comes out about 1.5-1.6 mm is baked at 500-550 deg C for
30-45 seconds..A 1.5 mm gap( producing nearly 2 mm on contraction ) is baked at 400 deg C for 90 seconds. In all these cases the dough expanded like basket ball but contracts upon removal from the oven to a flat bread forming an inner pocket. If you are using a 260 degree C oven heat desirable thickness will be in the vicinity of 3-5mm with a baking time of 2.5 to 4 minutes. In the bakery the timing when the pita is removed from the oven is when they fully expand to the ball shape and that it. Remove immediately, You want to use high temperature as you want the immediate vaporization of the dough water into steam that leads to pocket formation. Once that is done its already baked. regardless if its pale or dark it does not matter. Roy