By Peter Reinhart
When you go to the store to buy light rye flour for Marble Rye Bread, you may find several kinds of rye products on the shelves, especially at natural food markets, and the labeling can be confusing. Here is a guide to help you.
Light rye flour: Sometime labeled "white rye flour" or just "rye flour," this pale flour has had all of the bran and germ removed. It's the lightest of all the rye flours and, therefore, the one I recommend for the recipe. Medium rye flour: The name implies that some of the bran, and usually all of the germ, has been sifted out of the flour. In a pinch, you could use this for the marble rye, though it might be slightly denser.
Whole rye flour: Like whole wheat flour, this rye flour retains the bran and germ from the rye kernels. It can be packaged as "dark rye flour" or "stone-milled rye flour." Rye bran interferes with gluten development and makes a heavier bread, so I don't recommend it for the marble rye recipe.
Pumpernickel flour: This flour is a type of whole rye flour, milled coarser than regular flour so that the bits of bran and germ are more noticeable. In some breads, like pumpernickel, this flour is preferred for its added texture, but I don't recommend it for marble rye.