There are Two Small Changes in this Formula compared to the Vermont Sourdough—an increase in pre-fermented flour from 15 to 20 percent, and an increase in whole-grain flour from 10 to 15 percent—yet the effect on the dough is surprisingly large. The whole-rye flour offers considerable fermentable sugars and minerals to the yeasts in the levain culture, and this, combined with the increased proportion of ripe culture in the dough, produces a bread that is more acidic than the preceding ones. From a flavor perspective, this bread has a sharper tang and more of a whole-grain taste. Another effect of the increased acidity is a reduced extensibility, due to the acidity’s tightening effect on the gluten structure. Therefore, loaf volume will not be as great with this bread as in the two preceding ones. One fold might be preferable to 2 for this dough, as a second fold might bring too much strength to the dough. The whole-rye flour can be replaced with either medium-rye flour or whole-wheat flour. When mixing the dough, check the hydration carefully. Rye is quite absorbent, and a bit of extra water might need to be added to achieve a dough of medium consistency.