Maybe its time to begin looking at the dough itself? The way the dough is made can/will have an influence on the way it bakes and more specifically, browns. Remember, acid (low pH) inhibits the browning reaction. Fermentation produces acids as a byproduct, so as the dough ferments, it becomes more acid. Have you ever noticed how white a sourdough bread or roll is? Acidity. Is there a possibility that you have over fermented your dough? A good way to find out is to look at your dough management procedure (everything that happens to the dough between mixing and baking) but will also include the use of a sponge, poolish, starter or sour). High dough temperature will also greatly increase the rate of fermentation (80F is a good starting point for dough temperature). If you want to measure the pH of your dough as it is ready for the oven, go to the drug store and buy some litmus paper for use in the 4 to 5 pH range. Then take a couple ounces of your dough and put it into a blender with a cup, or s, of distilled water. Puree well, pour off into a clean glass and allow to stand for 3 to 5-minutes, decant off some of the cloudy water from beneath the sludge floating on top into a shot glass, dip the litmus paper into the liquid in the shot glass and compare the color to the color guide provided with the litmus paper and this will provide you with the pH of your dough. You should be looking for something not any lower than 4.2. If the pH is lower than 4.2 you are in the realm of a sourdough and will need much higher temperatures to bake the dough to the color you want. A good pH to shoot for is around 4.5 to 5.0 for your application.
Tom Lehmann/The Dough Doctor