This article mentions a test you can buy to determine how much gluten is left in fermented bread. Something to look into. The article below is a little friendlier to read and cover the what's known pretty well. In yet another article mention was made that the 1950's was when bread which used to undergo a long ferment was replaced by bread produced in a few hours. I'll look into that later...
Sourdough and Gluten II
Last weekend, I wrote a post about the capacity of sourdough fermentation to remove all significant traces of gluten contamination from gluten-free bread. I asked if any readers had seen studies exploring whether sourdough fermentation might also reduce gluten in bread made from gluten grains, like wheat.
Reader Max sent me a link to this study, suggesting it looked promising. He was right; it’s fascinating.
The team of scientists created a sourdough fermented bread using 30% wheat flour, and 70% flour made from grains determined to be safe for people with celiac disease (oat, millet, buckwheat). They fermented the wheat-containing portion of the dough for 24 hours, using select strains of lactobacillus that are especially good at breaking down gluten. After 24 hours, they added more non-wheat flour, fermented it for another two hours, and baked it. As a control, they made a second dough with the same ratio of flours, using yeast as a rising agent.
The result: tested on 17 celiac patients, 13 had no reaction to the sourdough fermented bread that included 30% wheat flour. The other four apparently had no reaction to either the sourdough bread or the yeast-risen bread (which confused me).
This team produced a wheat-containing bread that people with gluten intolerance could eat. This is striking. Currently, those with celiac disease and other serious gluten intolerance must avoid all gluten-containing products. While there are other reasons to reduce or avoid eating significant amount of grains, the ability to treat gluten grains in a way that those with gluten intolerance could tolerate is remarkable. The phrase “have your cake and eat it too” comes to mind. Best, the method used is based on an ancient, traditional practice.
This wasn’t the team’s only study on the sourdough fermentation and gluten. The 30% wheat study was a follow-up to the team’s previous study where, mimicking the typical process used for a wheat bread in Italy, they’d looked at gluten reduction in a 100% wheat bread that fermented four to eight hours. This process reduced the gluten, but did not eliminate it.
A few years after the success of the 30% wheat study, the team decided to approach the 100% wheat bread idea again with another study. This time, they fermented the bread for 24 hours. They also introduced three new variables. The 30% wheat study had a particular mix of lactobacilli; this study used that mix again, and called it S1. Then, they introduced another group of six strains of Lactobacilli sanfranceiscensis (yes, the kind original to San Francisco sourdough) which are particularly good at breaking down the relevant peptides. This was designated S2. On top of that, they experimented with fungal protease enzymes, from two different kinds of Aspergilllus. One, from A. oryzae is traditionally used to ferment miso in Japan. They called this E1. The second was from A. niger (E2). They baked sourdough fermented bread using a combination of these four variables. They analyzed gluten content of bread made six different ways:
-A yeast-risen control dough
-Sourdough made with S1
-Sourdough made with S2
-Sourdough made with S2 and E1
-Sourdough made with S2 and E2
-Sourdough made with S2, E1 and E2.
All fermentation batches (that is, everything but the yeast bread) reduced the gluten significantly. The second through fifth batches reduced the gluten by 73%, 83%, 93%, and 98% respectively. However, the final group, using the L. sanfranciscensis and both enzymes, reduced the gluten drastically -- from the yeast bread’s nearly 75,000 parts per million (ppm) to a miniscule 12 ppm, well below the threshold making it safe for those with celiac disease. With carefully-selected lactic acid bacteria and two enzymes, the team created a 100% wheat bread safe for people with celiac disease to eat.
I’m amazed. Maybe I shouldn’t be. I mean, fermentation has been around for pretty much as long as we’ve had foods that could be fermented. Cultures are smart and tend to figure out how to make foods digestible and nutrients available. Unfortunately, we’ve lost or nearly lost a lot of that traditional knowledge. But it’s always gratifying when research validates ancient cultural practices.
By the way, if the bread research wasn’t tantalizing enough, bread isn’t the only wheat-based food this group has looked at (see also this summary of sourdough and celiac). Leave it to a team of Italians to research ways to make pasta more accessible. It seems sourdough fermentation might reduce gluten in pasta too. I sense a new cooking project in my future.
Three final thoughts of caution before we all go swimming in vats of sourdough starter. First, make sure there’s a lifeguard at all tim--- Ahem. First, these studies were done with carefully selected strains of bacteria. I can’t promise you that sourdough projects at home will reduce gluten to the same degree. If you have celiac disease and want to experiment with this, consider testing your final product for gluten levels (you can buy testing kits here; I’ve never tried them).
Second, scientists are still learning about celiac disease and gluten intolerance. There may be some detrimental aspect of wheat that is not broken down through sourdough fermentation, but which hasn’t yet been recognized. This is just a speculation, but it’s the kind of thing that’s always worth keeping in mind.
Third, while I do think properly treated (soaked, sprouted, sourdough fermented), a moderate amount of grains can included in a good diet, I don’t consider them among the best foods for anyone. For some people they may not really work as part of an optimal diet at all, perhaps those with severe metabolic syndrome. Grains are also full of antinutrients and proteins that interfere with nutrient absorption and metabolism regulation, like feelings of satiety (being full). Aside from breaking down gluten, processes like fermentation break these down. But can fermentation (or soaking or sprouting) break down all of the nasties for all grains? Probably not.
I prioritize eating fresh, local, and sustainably produced meats, vegetables, fats, fish, fruit, nuts, dairy (especially fermented dairy), chocolate (yes, it’s a food group), and things like that. Still, grains, including gluten grains, have their advantages. They’re inexpensive, widely produced, and serve as a tasty base for all sorts of sauces and proteins, fats and vegetables.
I don’t have celiac disease, but based on digestive experiences, I do think I’m at least somewhat gluten intolerant. I’ve reduced wheat to almost nothing in my diet, and have been surprised that I miss wheat bread and pasta much less than I would have thought. Still, sometimes a piece of crusty bread with butter is, well, crusty bread with butter. For those with gluten intolerance, an occasional piece may not be so far out of reach.