People with celiac disease or various gluten intolerances may soon have a broader range of food options, thanks to advancements in research and the expanding industrial use of a traditional bread-making process: sourdough. Sourdough is a dough of varying consistency, depending on the initial ratio of flour to water, which undergoes spontaneous fermentation (due to naturally occurring microorganisms in the flour) or is based on an inoculum (previously selected microorganisms). During sourdough fermentation, fermentation microorganisms produce a series of secondary metabolites that directly influence or participate in subsequent chemical, biochemical, or metabolic reactions, affecting the essential characteristics of the end products: nutritional, sensory, aging behavior, overall quality, etc.
There is also a direct impact on the long-term effects of baked goods with sourdough on consumer health. These effects include starch digestibility (reducing the glycemic index and attenuating the postprandial glucose increase), formation of bioactive peptides (with antioxidant, anticancer effects and lowering blood cholesterol levels), gluten degradation, as well as other potentially allergenic proteins in the dough, such as amylase and trypsin inhibitors (due to a more drastic proteolytic activity of bacterial fermentation compared to yeast fermentation), solubilization of dietary fibers, increased bioavailability of minerals through a reduction in phytic acid, changes in the concentration and accessibility of certain phenolic compounds, sterols, vitamins, and the promotion of short-chain fatty acid-producing species in the intestinal microbiome.
Numerous scientific studies analyze these effects, but their meta-analysis provides many contradictory results, partly due to variations in bread recipes, experimental methodologies, and significant differences in sourdough microbial ecosystems that make them practically incomparable. A study worth noting, funded by the U.S. Department of Agriculture and conducted by researchers from Penn State and Colorado State University (Josephine Wee, assistant professor of food science at Penn State, and Charlene Van Buiten, assistant professor of food science and human nutrition at Colorado State University), is investigating whether bacteria in sourdough could help reduce gluten content in bakery products. In the U.S., gluten intolerance affects approximately 7% of the population, according to the National Institutes of Health, with 1% suffering from celiac disease. The incidence of celiac disease has increased by 7.5% per year in recent decades, reflecting a continuous rise in the prevalence of autoimmune diseases worldwide.
„A study of 500 sourdough starters collected from around the world showed that no two starters are exactly alike, and presently, little is known about the ability of the sourdough microbiome,” said Wee. „The outcomes of our research will leverage whole food microbiomes to develop fermentation technologies that will address the next generation’s consumer demands for high-quality, clean label products with reduced gluten immunogenicity.”
On the other hand, if sourdough research proves successful, it will have a significant impact on public health expenditures in the medium and long term, reducing the incidence of allergic reactions, environmental visits, and medication consumption. A substantial impact is also expected in terms of greenhouse gas emissions, as sourdough allows for the elimination of several ingredients from long food chains involving energy-intensive transport and production processes (yeast, chemical additives, enzymes, etc.). Moreover, unlike yeast, bacterial fermentation of the dough requires milder temperatures, approximately 22 – 28°C.
