In Search of the Perfect Loaf: A Home Baker's Odyssey (27 page)

At Weichardt, the starter was incredibly active, though that might have been due to the freshly ground rye, which has an excess of both fermentable sugars (rye exceeds wheat in this regard) and amylase enzymes (which you’ll recall convert starch into sugar). In fact, I’ve found that freshly ground whole grain flour is like high-octane fuel for sourdough, which is why I add it to my starter when it appears a little weak. The stuff perks right up. In any case, when Karl mixed up the starter in the afternoon for the coming night shift, he dumped two premeasured bags of freshly ground whole grain rye and wheat into the mixer, perhaps ten kilos (twenty-two pounds) in total, added three big buckets of water, and then a small pitcher of starter. I was skeptical this small amount of starter would ferment such a large batch of flour, but he assured me it was enough. The ingredients were mixed together, covered with a loose plastic sheet, and then left to ferment in the giant steel mixing trough for about eight hours, for the bakers who worked through the night.

The night crew then baked breads with this leaven and mixed more Backferment for the morning shift, which I got to see when I arrived. The rye-wheat mixture was thick and full of porous holes, like a sponge. It also had a sweet, grassy aroma, not at all acidic or alcoholic. We added more rye flour and wheat to the leaven to make the final dough, though in this case the word “flour” might be a bit misleading. Much of it was quite grainy, so that it appeared more like coarse whole grain breakfast cereal. We added water and salt and then turned on the mixer. This was a single-arm mixer, with the steel arm bent at the elbow. The arm would sweep down into the dough, grabbing some of mixture as it rose up, then letting it fall and flop over on itself. Compared with the most mixers I’ve seen, it was incredibly slow. If you took a spatula, or your hand, and slowly mixed a batter by raising and lowering your arm, the result would be much the same.

Seeing this process was an important lesson, for I realized that the mixer was very gently incorporating the ingredients, rather than developing gluten strength, as with wheat flour. The porridge-like dough slowly combined into a loose, grainy mass with hardly any springy elasticity. After twenty minutes or so in the mixer, the dough held together in a cohesive mass, but really didn’t look too different from the way it began. I realized I had to stop thinking about gluten when working with rye. Yet the curious thing about rye is that it
does
turn into bread. It does rise and it does get holes, even if small ones. The question I had was, how?

Rye grain, not surprisingly, differs quite dramatically from wheat. Its fiber soaks up an enormous amount of water, but it also has pentosan, a gumlike sugar which is far more prevalent in rye than in wheat and which also absorbs water. Rye proteins as a result go begging for hydration, and without sufficient water, they cannot rearrange themselves into anything like a gluten network. On top of that, rye has only a fraction of the glutenin proteins found in wheat, which are the source of elasticity and springiness, so rye can’t create the kind of gluten network that allows wheat bread to expand.

Without gluten, rye falls back on starch and that gumlike pentosan to form a loaf. When mixed with water, they turn into a kind of foam that traps carbon dioxide during fermentation. So the bread does indeed rise. Then when the dough finally hits the hot oven, starch granules expand and soak up water, causing some granules to burst open and form a viscous substance. Think of the way flour thickens when heated in a pan with water to make gravy. Known as “starch gelatinization,” this occurs in rye at 125˚ to 150˚F (52˚ to 66˚C). At the same time, sourdough microbes belch out ever more carbon dioxide gas into this viscous, gelatinous substance. Once the starch cools again after the bread is removed from the oven, the starch and pentosan form a semicrystalline structure known as “retrograde starch”—or liquid starch that has cooled and set. This becomes the bread’s crumb.

In wheat loaves, starch and pentosan are more like supporting actors in a crumb structure dominated by gluten, so you rarely even hear about them. But with rye, the bit players get the starring role, and they do their job admirably; that is, if they can avoid one big nemesis: amylase. These enzymes work like mad, breaking down starches into sugars, and wreaking havoc on the interior crumb you’re trying to create. Since amylase isn’t deactivated until 170˚F (77˚C), it has ample time to target the gelatinizing starches, destroying the crumb in the oven even before it’s fully formed. The result is that the interior of the bread can become a gummy mess. When you cut into a loaf that has suffered a dreaded “starch attack,” the bread knife will come out covered in brown gunk. It’s unpleasant, believe me. But the way to switch off these enzymes and ensure that your crumb will turn out just fine is to make the bread with sourdough, for its acidity keeps amylase in check and allows starch gelatinization to proceed. That’s why rye bread is traditionally made with sourdough. Without it, the loaf will end up more like porridge.

So here’s a tip: if you ever make gummy bread, which can be quite common in whole grain baking, increase the amount of sourdough in the recipe.
Peter Reinhart
, whose book
Whole Grain Baking
has one of the best discussions of enzymes I’ve come across in a baking book, usually pre-ferments about half the total flour in a recipe in the sourdough starter. Compared with most recipes, this proportion of sourdough is quite high, but it does the trick. The amylase is snuffed out.

Aside from deactivating this enzyme, sourdough improves the quality of whole grain bread in another important respect. It mitigates the damaging effect of bran, which can degrade gluten and the connections it forges with starch. During fermentation, sourdough converts bran fibers into soluble polysaccharides, those long chains of starches that can contribute to the formation of the crumb. But to get this result, the bran needs a sufficiently long fermentation of eight to twenty-four hours. “It turns a negative element into a positive one,” the sourdough researcher Michael Gänzle told me. This is why you should always make whole grain bread with sourdough.

But here’s another counterintuitive tip: make sure your whole grain flour isn’t milled too finely, because it may interfere with the formation of gluten. While I’ve often heard from bakers that bran “cuts” gluten—implying that finer bran wreaks less havoc—this seems questionable.
Cereal scientists suggest
that the enzymes and chemicals in bran inhibit gluten, and exposure to these substances increases the more finely the bran is milled. Studies show bread volume goes down noticeably with finer bran. So don’t be afraid of coarsely milled whole grain flour: it may produce a better rise. At least it did at Weichardt.

 • • • 

N
ow, the Weichardt rye-wheat loaf tasted grainy, full of deep and earthy flavors. The Backferment, being mild in nature, meant that the freshly ground grains weren’t masked by any harsh acidic overtones. This bread also had a kind of resistant chew when you bit into it, with flecks of bran and grain, making for a varied texture. With a schmear of butter, the bread was quite satisfying, but at most, I could eat two pieces sliced extremely thin, no more than a quarter inch wide. Karl told me that he sometimes had a slice of rye in the morning, and that was it. One slice didn’t do it for me, but two would keep me going for a long time. The bread fueled a very slow burn.

Whole grains, as it turns out, do metabolize slowly, though to understand that we have to jump beyond the taste buds and into the nether regions of the alimentary tract. The scientific literature is replete with
the benefits of whole grain fiber
, noting the speed of “intestinal transit” and higher “fecal bulking weight” (that is, the stuff spends less time in the colon so there’s less chance of disease-causing cell mutations). Among the health benefits we hear so much about, whole grains lower cholesterol and reduce the risk of cardiovascular disease. They also modulate blood sugar levels, not just when they are eaten but also for the following meal—so a bowl of oatmeal at breakfast slows the metabolism of carbohydrates at lunch. Refined carbohydrates, like white bread, work very differently, quickly converting into glucose and causing blood sugar levels to spike. This, in turn, causes the pancreas to pump out more insulin, which channels these sugars to the body’s cells. Over time, on a diet high in refined carbs, insulin resistance can kick in and eventually may lead to type 2 diabetes, where blood sugar levels soar. Whole grains temper this entire chain reaction, because fiber doesn’t convert to sugar but instead moves through the entire intestinal tract.
Coarsely ground grains magnify
the effect, because the digestive tract has a tougher time extracting the carbs.

In this equation, sourdough fermentation helps, too. Lactic acid slows the pace of starch digestion, while acetic acid prolongs the rate at which food passes through the intestine. This one-two punch from sourdough is so powerful that
white sourdough bread raises
blood glucose levels less than whole wheat bread made with yeast, despite its higher fiber content! In this way, sourdough tempers sugar shock.

But sourdough does something else quite beneficial, transforming rapidly digested sugars into nondigestible fibers. These fibers, known as exopolysaccharides, pass undigested through the stomach and into the body’s colon. Once there, they become food for bacteria, which gobble them up and turn the large intestine into a fermentation crock.
These fibers are known as “prebiotics,”
because they feed the biota that live within us. Along with resistant starch—or starch that hasn’t been digested—and plant fiber, gut bacteria ferment this fibrous feedstock and multiply.

Although colonic fermentation may not sound appealing, it helps keep us alive. One of the beneficial by-products of microbial fermentation is
short-chain fatty acids
, which lower cholesterol and facilitate the absorption of electrolytes. As athletes know, electrolytes are especially important to maintaining hydration. But perhaps most important, these gut microbes reduce inflammation and in so doing may play a protective role in preventing ulcerative colitis, irritable bowel syndrome, even colon cancer.
One study published in the spring of 2013
found that when people were fed a multigrain diet, their gut microbial communities flourished along with the compounds that fight inflammation. While studies have been inconsistent on the relationship between whole grain consumption and, say, lower risk of cancer, an eleven-year European study of 470,000 people recently concluded that fiber plays a protective role. The bottom line of this research: you want to keep your colonic fermentation tank bubbling away.

There’s an elegance, too, in this ecological relationship. Sourdough microbes, which, as you’ll recall, likely originate in the intestines of rats, pigs, chickens, fruit flies, or humans, find their way into dough; once there, lactobacilli eat carbs and belch out carbon dioxide and create exopolysaccharides; when we eat sourdough bread, these fibrous compounds flow through the stomach and to the colon; once there, the microbes that inhabit our intestines gobble up these fibrous fermented food products and create fatty acids that help us live. It’s one big happy circle of microbial ecology, fueled by fermentation inside the body and out.

One more potential benefit of sourdough must be mentioned, which relates specifically to celiac disease and to the anecdotal reports I often hear about sourdough bread being easier to digest. Over the past decade, scientists have found that certain strains of lactic acid bacteria can degrade gluten to the point that it is undetectable. That is quite a feat, for it suggests that sourdough digests gluten and in this way could potentially make wheat less toxic for gluten-sensitive people. One of the foremost scientists behind this work, Mario Gobbetti, head of the Department of Plant Protection and Applied Microbiology at the University of Bari in Italy, told me that it wasn’t simply “sourdough” that did the trick, as in the sourdough that’s sitting on my kitchen counter. Rather, the handful of microbes he’s selected were the most powerful gluten-digesting creatures his lab could find in more than one thousand sourdough starters in Italy.