The color and taste of the bread depend on the kind of flour used and the style of baking. Flour made from the whole grain gives darker bread. Flour made just from the polished wheat grain gives a very white bread. Rye and barley flour give darker types of bread. The type of flour also changes how long the bread can be kept before going bad. Some strains of wheat are resistant to fungus, but may not produce a bread as tasty as a weaker strain.