After wheat, rye is the second most important grain for the bread baker. In much the same way that wheat flour comes in varieties ranging from white to medium to dark (100 percent whole wheat), rye does as well. These gradations are a function of how much of the original kernel remains in the final flour, with paler flours having more of the outer layers of bran and endosperm removed. Darker, more whole grain flour absorbs liquid more readily.
You may have noticed that rye bread is often denser than wheat. This is because although rye has the same gluten-forming proteins as wheat (glutenin and gliadin), it doesn’t have them in the same ratio as wheat; when compared to wheat, rye has only 10 percent the amount of glutenin. Still, rye has its own signature flavors and aromas, expanding the baker’s arsenal, and I find it indispensable to sourdough starter and as a supplement to many of my commercial yeast starters. It adds a note of aromatic sweetness that reminds me of premium vodka, and the accelerated way it interacts with yeast jump-starts and amplifies fermentation. In a final dough mixture, white rye adds a distinctive sweetness. Dark rye also contributes a deep brown color that makes for an appealing appearance: one that says “put some cold cuts or hard smoked cheese on me.” I find rye to be an ingredient that plays well with others; it’s great in a supporting role but challenging as a solo act. When it’s the primary flour, it makes for a super-dense bread—something I want to make only occasionally and only for specific reasons, like to serve with smoked wild salmon. Because rye adds such distinct flavors, depending on whether it’s white rye, medium rye, or dark rye, I recommend that you stay with what I call for in the recipes. I’ve done many experiments to arrive at the flavor profile of each bread, and I’ve learned from my mistakes so you don’t have to.
Oats can grow and prosper under conditions that won’t produce thriving wheat. I think that’s part of the reason oats were traditionally used for animal feed in many places where wheat wasn't cultivated. They don’t contain gluten-producing proteins, however, and for that reason they’re daunting for bread makers because they don’t contribute to the crumb of a loaf. I think you may already have a good idea about where I stand on the gluten issue. For most people they provide good, high-quality nutrition. The bottom line is that I rarely use oats in flour form (the exception is Toasted Oat Bread).
I wish we had a tradition of using cornmeal more often in bread. It’s high in natural sugars, so it turbocharges fermentation and adds sweetness. As a baker who likes to work with local grains, it’s hard to find anything more genuinely local or American than this amazing grain, which was first hybridized more than ten thousand years ago by Native Americans. Although they lacked the wheel and other technological advances, the fact that they created corn from its genetic forebears out of the combination of three wild grasses points to a very sophisticated grasp of agriculture. Corn does have a small amount of gluten; however, it’s chemically and structurally different from wheat-based gluten, so it doesn’t create the same sort of air pockets and crumb. That said, the sweet butteriness it brings to a loaf is attractive. Plus, when cornmeal is fermented, it basically creates a mixture similar to a bourbon mash. This gets my vote right away. On the downside, breads made with cornmeal tend to stale quickly, so they should be eaten within a day or so.
Buckwheat isn’t a grain in the conventional sense of the term. Rather, it’s the seeds from a plant related to rhubarb and sorrel. Historically, buckwheat flour was used to fortify dough when wheat was at a premium. Today, buckwheat is mostly used as a cover crop that helps replenish nutrients in the soils of fields where wheat and other grains are grown. I particularly like the idea of using a plant that helps soil stay fertile. Happily, buckwheat also imparts some wonderful and unique flavor characteristics to bread. When fermented, it contributes deep, nutty aromas and light alcohol notes without increasing acidity. As with wheat and rye flours, there are lighter and darker forms of buckwheat flour, but in this case the color has little effect on nutritional value. I’ve also found that it doesn’t affect how buckwheat flour interacts with other ingredients.