Whole-grain rye is a 100% whole grain product that includes wheat bran, germ, and endosperm. It has a dark color because the bran is not removed in the milling process.
This grain is closely related to wheat, but is darker and denser, with a slightly sour taste. Rye is high in soluble ﬁbre but low in gluten.
When using rye to bake bread, you can often achieve better-rising results by substituting a third of the amount of rye called for in a recipe with wheat. Whole-grain rye is often used to make rye bread and sourdough bread.