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.
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Now, 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 i
nto 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.
I was curious about the origins of the idea. I mean, why even test sourdough for its ability to degrade gluten? “The idea for this research actually came from my father, who said and still says that the sourdough bread made by his grandmother was much better than the bread we eat today,” Gobbetti told me. I refrained from interjecting that his father must be a smart man. “In some instances, when he had digestive problems, he felt better by eating this bread. Obviously, the observation was anecdotal. But that’s where the idea came from.” I almost laughed. Of course, the source of this scientific inquiry arose from bread made by an Italian grandmother!
At the beginning, Gobbetti thought nothing would come of the work, but he went ahead nonetheless. The results turned out to be surprising. Not only was his lab able to use this specially prepared sourdough cocktail to degrade gluten to below the EU “gluten-free” standard of twenty parts per million, they also fed bread made with gluten-degraded flour to celiac patients who in short-term studies showed no adverse reaction. Baker’s yeast, the lab found, had no such properties. The researchers in Gobbetti’s lab recognized this difference explicitly, noting that the fast fermentations common in industrial breads weren’t doing anything to reduce the disease-related cereal proteins in wheat. Maybe, I asked Gobbetti, the historical loss of sourdough-fermented breads made people in general more vulnerable to celiac disease? He admitted that was an interesting hypothesis but it hadn’t been substantiated in any epidemiological studies. Those types of studies would be difficult to conduct unless you could find a population of people who exclusively ate sourdough bread.
When I asked him whether the sourdough I used in my own kitchen would have a similar gluten-degrading effect, he stressed that his lab had identified a special team of lactic acid bacteria. “What we do with these bacteria to break down gluten cannot be done at home,” he said, stressing the last part of his statement. Still, I pressed, thinking that even my sourdough would have some power over gluten, even if minimally. After all, wasn’t it his father’s folk wisdom that set him down this path in the first place—that his grandmother’s sourdough bread was easier to digest? Gobbetti eventually did concede that my sourdough might have some slight effect on gluten, it was just uncertain how much. Maybe it was 0.1 percent, maybe 10 percent, of what they were achieving in the lab; it was all speculative and depended on those little microbes I had in residence, how long my fermentations lasted, and even the type of wheat I used. Overall, he stressed, “Don’t try this at home.” Homemade sourdough will not produce gluten-free bread, though I do accept the anecdotal evidence that it may be easier for some to digest.
All of this research makes clear that sourdough microbes can alter the nutritional profile of bread. The more I looked, the more I found. Studies have shown that sourdough fermentation can maintain the level of thiamine (vitamin B1) found in whole wheat bread, even after baking. Certain strains of lactic acid bacteria can boost the level of riboflavin (vitamin B2) by two to three times. As if that weren’t enough, sourdough breaks down phytic acid, which is concentrated in the innermost layer of bran and blocks the body from absorbing beneficial minerals also found there, such as iron, calcium, magnesium, and zinc. Yeast and baking powder lack this power to neutralize phytic acid, which means mineral absorption declines when you make whole wheat bread with these methods. (Mineral deficiencies aren’t a problem in wealthier parts of the world, but in poorer countries they constitute a major health problem.) Now, I’m not knocking your morning bran muffin made with a leavening agent such as baking powder, because you still get the intestinal benefit of fiber. But with sourdough-fermented whole grains, the bacteria neutralizes much of the phytic acid in the bran and frees these essential minerals to be absorbed by the body.
White flour, of course, lacks many of these benefits. Because milling removes the bran and the germ, vitamin E, vitamin K, and a range of minerals—calcium, magnesium, phosphorus, potassium, zinc, copper, manganese, and selenium—are depleted as well. A few nutrients, such as iron, thiamin, riboflavin, niacin, and folate, are added to white flour through “enrichment,” but even these additions don’t make up for the wide range lost in the bran and germ. Add in zippy yeast fermentation and the result is a loaf as devoid of taste as it is of the many nutritional benefits I’ve just described.
One day, Heinz Weichardt was talking to me about the nutritional superiority of using freshly ground whole grains and Backferment in making bread. In retrospect, there was quite a bit to support what he was saying. But Weichardt didn’t need a nutritional label or a health claim to persuade customers to buy a loaf. Customers were not seeking a colonic aid, or a fiber boost. They were just buying bread. Roggenweizenbrot may have had a whole range of health benefits from its freshly milled whole rye and wheat grains, but at the end of the day it was just a good loaf: dense, yes, but almost addictive once you started eating it. At its apogee, food should sustain the organism, by tasting good, by feeling good in the mouth, by satisfying you, and by giving you sustained energy. Weichardt’s bread scored on all those counts.
Sadly, such loaves are still few and far between in the United States. As I visited San Francisco’s Tartine bakery over the course of a couple of years, Chad Robertson was moving more assertively into whole grains, influenced by rye bread he had encountered in Denmark. His bakers were constantly experimenting with grains like barley and emmer and his cooks at Bar Tartine had built a menu around thinly sliced grainy rye, known as Danish Rugbrød. Yet, when I visited the restaurant for lunch, there weren’t yet lines out the door. Those could be found around the corner at the Tartine bakery, where people were clamoring for the country loaves, made with sourdough and the more familiar white flour. But maybe that will soon change. I’ve come across a handful of bakers in various parts of the country making eastern European–style loaves. One in Brooklyn makes Latvian-style ryes. Another in New York makes Finnish Ruis loaves that are grainy and quite good. In New Haven, WholeG sells terrific German-style ryes at the farmers’ market, but truthfully, these whole grain bakers are few and far between. Hopefully, like heirloom tomatoes in the 1980s, they will soon have their day.
• • •
So, in Berlin, did I find that dense, rich, dark rye bread I ate as a kid in New York? I would have to say no. These German breads were different, with far more rye than I think I’ve ever encountered and also greater variety, but they were a distant echo of what I had eaten. There were other unexpected connections with my Jewish culinary roots, like the braided Zopf I made with Karl. If you didn’t know better and were visiting Weichardt Brot on a Friday, you might mistake it for challah. Then, walking through Prenzlauer Berg in East Berlin one Saturday morning, I came across a crowded farmers’ market where se
veral stands were selling smoked and pickled fish. I associate these foods with Russ & Daughters on New York’s Lower East Side, Zabar’s on the Upper West Side, and the Sunday brunches of my childhood with my family in Brooklyn. Sprotten, a bite-size smoked whitefish that you eat whole, and the pickled herring would have made any Jewish appetizing store in New York proud. Another day, I visited the famous KaDeWe department store and rode the elevator up to the giant food emporium. I stood in line behind a modestly dressed working man who bought a pickled herring sandwich and I swear inhaled it. I went for the smoked mackerel, which was quite rich, oily, and oddly familiar.
All these delicacies were virtually identical to ones I associated with New York Jewish food—the food my dad loved. But what I didn’t expect was to hear his words. One day, when I was standing in the bakery with a few of the bakers, Mucke Weichardt said in the midst of a conversation, “Verstehst du?” as in, “Understand?” I picked out the word because the pronunciation sounded so much like the Yiddish my dad would use: “Farshteyn?” With one word, an entire world came rushing in, for I hadn’t thought about the way he used that phrase in years. And then I began recalling a few of the Yiddish words he would use. I mentioned this to Karl and we began trading Yiddish and German equivalents. And so here I was braiding Zopf, not challah, listening to German, not Yiddish, and eating pickled herring in Berlin, not New York. I had this overwhelming sense of connection to my past, in Berlin of all places, with its profusion of Holocaust memorials. It turned out to be the most surprising thing about the trip.
In Search of the Perfect Loaf: A Home Baker's Odyssey Page 20