Want to extend the shelf-life of your homemade bread? Substituting a little rye flour may be just the ticket.
Traditional German and Scandinavian breads made with 100 percent rye flour are known for staying fresh for weeks after baking. This is because rye flour is rich in water-absorbent carbohydrates called pentosans that allow it to hold ten or more times its weight in water. (Wheat flour is only able to absorb twice its weight.) What’s more, pentosans don’t retrograde (stale) and harden into a crystalline structure after baking and cooling, as the starches in other flours do.
We wondered if we could use rye’s anti-staling properties to preserve bread, so we made three loaves of our whole-wheat sandwich bread: one according to the original recipe (which calls for 2 cups of bread flour and 3 cups of whole-wheat flour), one in which we replaced 3⁄4 cup (25 percent) of the whole-wheat flour with rye flour, and one in which we subbed 1 1⁄2 cups (50 percent) of rye flour for the whole-wheat flour. (Rye flour can’t be directly substituted for all-purpose or bread flour because it has different gluten-forming properties.)
After storing the bread for five days unwrapped and at room temperature, we compared the loaves. Unsurprisingly, the all-wheat loaf was stale, tough, and dry. The 25 percent–rye loaf had fared only slightly better, but the loaf made with half rye and half whole wheat was remarkably soft and moist—and stayed that way for two more days. The rye did add its characteristic flavor to the loaf but didn’t appreciably alter its texture. The bottom line: If you don’t mind the distinctive flavor of rye, swapping half of the whole-wheat flour in a bread recipe with rye flour will make it shelf-stable for up to a week.