When family members eat and enjoy bread again after years of avoiding it, it is pretty easy to guess there must be some pretty solid health benefits from eating sourdough bread. But after looking into it further, I really was surprised at the difference fermenting flour could make, (sourdough is a bit of a misnomer, in that it is actually fermented flour and water that tastes somewhat sour). Things like vitamin and mineral bioavailability, digestibility, and other nutritional properties, along with extended shelf life, not to mention the excellent flavor and aroma

My personal experiences with sourdough baking began with a bread class at Abagail’s Oven more than two years ago. There Martha Levie explained that some people who are gluten intolerant can eat their products without suffering intestinal distress.

While not everyone who is gluten-intolerant can eat sourdough bread. That was the case for my sister-in-law who had stopped eating bread because of gluten sensitivity. I got her to try some and she tolerated it well. Thas is when she began purchasing it at a nearby store.

Eventually, I gave them some Einkorn flour and some of my start. Since then she and her husband have purchased some of Abigail’s Oven Premium White Whole-wheat and have made bread that she can eat. Still, she prefers the convenience of just picking up bread at the Good Earth when she needs a loaf.

Since taking that class two years ago, I have baked hundreds of loaves and after buying my premium white whole-wheat flour I started making bread nearly every day for family, friends, and neighbors. I have also taken Martha’s challenge and started using sourdough to make biscuits, dinner rolls, and pancakes. Over time I have given up using any baker’s yeast.

Before I started making my own sourdough bread, I didn’t really think about what was in commercial bread that we had been eating. But I knew my sourdough bread tasted good—it was like the bread I had eaten in Europe. Since so many folks I know suffer from sugar spikes, bloating, and gluten-intolerance, I thought it was time to investigate the science behind the natural fermentation and go beyond my love of the taste.

In Foods,  Luana Nionelli and Carlo Giuseppe Rizzello wrote that “Sourdough fermentation positively influences all aspects of baked goods’ quality such as texture, aroma, nutritional properties, and shelf life.”[1] Let’s follow their claims to study the science behind sourdough more closely:

  1. Texture and Structure
    They reported that the fermentation process in making sourdough bread increases the “bread extensibility, softness, and volume.”[2]  To make this point they cited four studies (#1,#2,#3,#4,#5), that may interest readers too. They also pointed to the superior retention of carbon dioxide gases in the sourdough process that gives the dough lighter structure.[3] Further, this process breaks down gluten and interferes with unwanted enzymes through acidification, which also fosters “shorter mixing time and less stability than normal dough.”[4]
  2. Flavor
    The ingredients a sourdough start (water and flour) really have no flavor by themselves. Real sourdough bread also only uses the start, flour, water, and some salt, also essentially flavorless. But once the start begins the fermentation process between these ingredients, a distinctive taste develops. The flavor comes from beneficial bacteria and yeast that fight to grow and survive in a complex microscopic ecosystem that evolves over hours or days.[5] Each start depending on its area of origin develops a unique flavor based on whichever bacterium and yeasts have been combined. Also “sourdough fermentation results in a large increase of free amino acids, compared to the baker’s yeast process.” All of which improves the flavor.
  3. Nutrition
    Studies show that the acidic processes of fermentation improve the texture of whole grain high fiber bread.[6] At the same time increasing our ability to absorb the minerals and vitamins, especially found in whole wheat flour.[7] The acids also slow digestion causing the sugars in sourdough to be more slowly absorbed and metabolized. This causes a lower and slower rise in blood sugar, and, therefore usually, insulin levels.[8]
  4. Shelf Life
    Natural fermentation of dough improves loaf “volume and crumb softness by sourdough fermentation have been associated with the decrease of the rate of bread going stale.” Their research further showed that the process was “characterized by a large inhibitory spectrum against [fungus and mold] species that commonly contaminate baked goods and bakeries [and], allowed a long storage of bread (at least 21–28 days).”[9]
  5. Improves Gut Health
    The report finds that sourdough fermentation offers “potentially prebiotic exo-polysaccharides” which can be useful in gut health because it decreases the number of pathogenic bacteria. And then there is this: “The action of making bread is a kind of restoration of certain kinds of biodiversity into our food, onto our bodies and throughout our houses in a way that connects all of these processes. When we make sourdough starters, our bodies and homes flavor our daily bread. And in making sourdough starters, the flour, starter, and bread enrich our bodies and homes.”—Rob Dunn, Inside the fascinating (and delicious!) science of sourdough bread, ideas.TED.com, Dec 19, 2018
  6. Inhibits Tumor Growth
    Their study “sourdough lactic acid bacteria [has been shown] to release lunasin, a strong anti-tumoral peptide,” which inhibits the spread of certain human carcinomas.[10]
  7. Delivers Antioxidants
    Antioxidants have been seen in selected lactic acid bacteria during the fermentation of sourdough.[11]
  8. Regulates Blood Pressure
    The process of fermentation has also been shown to produce “anti-hypertensive peptides,” especially from whole wheat flour, which helps regulate blood pressure. [12]
  9. Eliminates FODMAPS
    An Australian study discovered that people with gluten sensitivity found relief when avoiding commercial bread, bananas, and garlic all of which contain fructan (also called FODMAPS). However, the fermentation process of sourdough bread leaves no fructan.
  10. Improved Mineral Absorption
    Other studies
    show a reduction in phytic acid, which is found in whole wheat flour. This acid blocks the absorption of the mineral-rich properties of whole wheat but is broken down during sourdough fermentation.

Nionelli and Rizzello concluded: “Together with recent medical and technological advances, sourdough-based biotechnology could contribute to improving the quality of life of coeliac patients in the near future.” And all of these studies offer insight into the health benefits of consuming sourdough, but for me, flavor and real ingredients are what counts.


References

1 Nionelli and Rizzello; Sourdough-Based Biotechnologies for the Production of Gluten-Free Foods; Foods, Sep 2016. 
2 Corsetti, Gobbetti, De Marco, Balestrieri, Paletti, and Rossi; Combined effect of sourdough lactic acid bacteria and additives on bread firmness and staling; J Agric Food Chem. 2000 Jul; 48(7):3044-51. 
3 Hammes and Gänzle; Sourdough breads and related products; Microbiology of Fermented Foods. Volume 1. Blackie Academic/Professional; London, UK: 1998. pp. 199–216.
4 Hoseney; Principles of Cereals Science and Technology, 3rd ed; AACC International; St. Paul, MN, USA: 2010. 
5 Damiani, Gobbetti, Cossignani, Corsetti., Simonetti, and Rossi; The sourdough microflora. Characterization of hetero- and homofermentative lactic acid bacteria, yeasts and their interactions on the basis of the volatile compounds produced. Lebensm. Wiss. Technol. 1996;29:63–70. 
6 Katina, Arendt, Liukkonen, Autio, Flander, Poutanen; Potential of sourdough for healthier cereal products; Trends Food Sci. Technol. 2005;16:104–112.
7 Lopez, Krspine, Guy, Messager, Demigne, Remesy;  Prolonged fermentation of whole wheat sourdough reduces phytate level and increases soluble magnesium; J Agric Food Chem. 2001 May;49(5):2657-62.
8 De Angelis, Rizzello, Alfonsi, Arnault, Cappelle, Tossut, Di Cagno, Gobbetti; Use of sourdough lactobacilli and oat fibre to decrease the glycemic index of white wheat bread. Br. J. Nutr. 2007 
9 Rizzello C.G., Cassone A., Coda R., Gobbetti M; Antifungal activity of sourdough fermented wheat germ used as an ingredient for bread making. Food Chem. 2011;127:952–959.
10 Rizzello C.G., Nionelli L., Coda R., Gobbetti M.; Synthesis of the cancer-preventive peptide lunasin by lactic acid bacteria during sourdough fermentation.; Nutr. Cancer. 2012;64:111–120
11 Coda R., Rizzello C.G., Pinto D., Gobbetti M.; Selected lactic acid bacteria synthesize antioxidant peptides during sourdough fermentation of cereal flours; Appl. Environ. Microbiol. 2012;78:1087–1096.
12 Rizzello C.G., Cassone A., Di Cagno R., Gobbetti M.; Synthesis of angiotensin I-converting enzyme (ACE)-inhibitory peptides and gamma-aminobutyric acid (GABA) during sourdough fermentation by selected lactic acid bacteria; J. Agric. Food Chem. 2008;56:6936–6943.