rye breads are most popular in continental Europe north and east of the Rhine; in Scandinavia; and in N. America where immigrants from these areas have settled. They are made from pure rye, or rye and wheat mixed (a combination known historically as ‘maslin’ in Britain), and are often flavoured with caraway, aniseed, fennel, or cumin.
Because its seeds are greyish-green, it is impossible to make pure white flour from rye. Bread made from rye flour with all the bran removed is pale grey. Wholemeal rye flour gives ‘black bread’, which is really dark greyish-brown unless some colouring agent is added. Rye is low in gluten, the substance which gives wheat bread its light, elastic texture; so rye bread is always rather dense. However, its total protein content is only slightly lower than wheat, and rye bread keeps moist for longer than wheat bread, thanks to a small amount of natural gum in the grain which traps moisture, and which is also responsible for its characteristic stickiness.