There’s something special about sourdough bread. Made through a slow process that begins with simple ingredients, warm water and flour, yeast and bacteria feast on the flour’s carbohydrate, producing carbon dioxide gas and bubbles that expand the dough. Each batch may tastes a little different depending on the flour and water used as well as the environment the starter is made in. My favorite sourdough bread, the kind that is made over the course of several days, has an alluring pungent, slightly sour taste. This long fermentation process leads to more complex flavors while also creating bread that is easier for those with gluten sensitivity to digest. I shared the science behind sourdough in this segment on Fox TV:
What is Gluten?
Gluten’s stretchy fibers give dough it’s rubberband-like elasticity allowing it to stretch when pizza dough is tossed in the air like a frisbee. Gluten-rich dough traps air and water during the baking process so bread rises with delicate ease, producing light and fluffy baked goods. Without wheat (and therefore gluten, which is produced when wheat flour is mixed with water), gluten free items require a blend of flours, starches and additives yet they still can’t replicate the texture of gluten-containing baked goods.
In people with celiac disease, an autoimmune digestive disease, repeated exposure to gluten damages villi, fingerlike projections in the small intestine that help us absorb nutrients from food. Over time, a decrease in nutrient absorption can lead to anemia, osteoporosis, miscarriages and other complications. The University of Chicago Celiac Disease Center website lists over 300 symptoms associated with celiac disease though anemia is the most common symptom in adults. The only available treatment is a strict gluten free diet – which helps reverse intestinal damage over time. Gluten sensitivity is not an autoimmune disease but instead a vague medical condition without a uniform definition or diagnostic test at this time. People with gluten sensitivity report various symptoms triggered by the ingestion of gluten-containing foods including abdominal pain, bloating, and constipation or diarrhea. Though gluten sensitivity is real, someone who thinks they have sensitivity may actually be reacting to something other than gluten (another protein or the starches – see below under Is it the Gluten?)
The Science behind Sourdough
Standard yeast leads to a fast fermentation process. This ramps up production speed and it is also foolproof so companies can produce batches of bread at warp speed. Sourdough bread is made slowly, over time, letting the yeast work it’s magic to deliver an array of flavors as well as bread that is easier to digest. In one study, sourdough bread made with selected sourdough lactobacilli and long-time fermentation resulted in bread with gluten levels of 12 parts per million (ppm), which qualifies for gluten-free (anything below to 20 ppm is gluten free). A long fermentation process allows bacteria and yeast adequate time to feed on proteins and starches breaking them down into more digestible parts. Yet sourdough also boasts a lower glycemic index than many other types of bread (including white bread) and therefore it doesn’t lead to a quick spike in blood sugar levels.
In 2011, a small study conducted in Italy tried giving volunteers with celiac disease a small amount of specially prepared sourdough bread. The bread was fermented until the gluten was broken down to more easily digestible parts. The subjects in the study reacted well to the sourdough, with no changes in intestinal villi and no detectable antibodies typically found when a celiac disease patient eats a gluten containing food. According to the study authors, the bread “was not toxic to patients with celiac disease.”
In another study, conducted over 60 days, baked goods made from hydrolyzed wheat flour, manufactured with sourdough lactobacilli and fungal proteases, was not toxic to patients with celiac disease. Though these studies are groundbreaking, it is far too soon for celiac disease patients to try this at home. For sourdough bread to be an option for those with celiac disease, a uniform production process would need to be established to ensure the end product is gluten-free.
For those with Gluten Sensitivity, Is it Really the Gluten?
Some people may experience bloating and flatulence in response to FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides and polyols). FODMAPs are a type of carbohydrates that are not well absorbed in the small intestine and are present in bread along with a number of other foods (other grains, some vegetables and fruits). In some people the problem may be FODMAPs, not gluten. The long fermentation process reduces FODMAPs.
How to Make Sourdough at Home
Sourdough starter begins with flour and water that sits for several days while being fed intermittently with both flour and water allowing bacteria (lactobacilli) and yeast to grow and multiply creating live cultures. These microorganisms are what makes the dough ferment similar to the way milk ferments to become yogurt. Check out these recipes to make your own sourdough bread: Healthy Aperture, the Perfect Loaf.
If you run into problems making sourdough check out this page for troubleshooting.