Sourdough | History Rises Again
May 15, 2019 Annabel Slater By Annabel Slater

Sourdough | History Rises Again

Today sourdough is considered an artisanal bread, but 160 years ago nearly all bread was sourdough. What changed?

Sourdough – History rises again

No one knows who made the world’s first raised bread. But it’s likely to have happened after humans invented agriculture. Settling in one place, experimenting with mixtures of grain, someone probably noticed a mixture of crushed grains and water forming bubbles after a few days – the tell-tale sign of fermentation.

From Fermentation to Sourdough

Fermentation occurs when microbes (like bacteria and yeast) digest substances, producing gas and other products. Milled flour naturally contains strains of Lactobacillus bacteria and wild yeast from the environment, and these microbes can digest starches and sugars in the flour. Ancient civilisations would have found out that this frothy mixture, when baked, produces a softer and fluffier alternative to early flatbreads. This began the trend of ‘leavening’ bread, making bread rise by incorporating substances (like microbes) to put gas bubbles in the mixture.

Sharing the Dough

Does this process sound familiar? It’s actually how sourdough is traditionally made! So ancient leavened bread was just sourdough. Sourdough was eaten by the ancient Egyptians, taken to America by French bakers during the Gold Rush, and nurtured in bakeries across Europe.1

So what changed? Eventually bakers figured out that it was yeast that did the bulk of the leavening–adding yeast to a dough mixture gave fast and reliable results. In 1857, French microbiologist Louis Pasteur identified yeast under the microscope, which led to the creation of commercial baker’s yeast. Bread production was transformed, and sourdough was no longer the only option.2

Fun fact: For a while, bakers used brewer’s yeast which gave the bread a bitter flavour.

What’s in a sourdough?

But Lactobacillus and yeast don’t just change the texture of bread, they change its chemistry. Raw sourdough is a living thing, a changing blend of microbes, and it’s the natural balance between the yeast and bacteria which makes sourdough so special.

As the microbes grow and live and ferment, the Lactobacillus produce lactic acid and the yeast produce alcohol, giving the bread a tangy and acidic flavour. The acid in the dough also keeps out other types of fungus and bacteria, so the eventual bread has a longer shelf life. The microbes also digest gluten, meaning that real sourdough should either be low in gluten or gluten-free—so people with gluten-intolerance and celiac disease to might be able to eat sourdough.3

Fun fact: The lower amount of sugars means sourdough also has a lower glycaemic index than many types of other bread.

You might be eating 100-year-old sourdough

In the past, bakers found they could save some leavened sourdough to add to new mixtures, which would convert them into more sourdough. With careful feeding of flour and water, these so-called ‘starter doughs’ can be kept alive indefinitely. In fact, there are starter doughs in modern bakeries that may be hundreds of years old.

Across the world, jars of starter doughs have been treated like family heirlooms, passed down through generations. Starter doughs were carried by frontier settlers and Gold Rush prospectors, snuggled at night to keep them warm and alive.

Fun fact: Each starter dough really is unique, a potted history of local flour and microbes from the environment - including the Lactobacillus found naturally on the baker’s hands.4

Traditional sourdough continues to be made and sold today in bakeries and artisanal markets. There’s a sourdough library in Belgium which aims to collect and catalogue starter doughs from around the world.5 In Sweden, a sourdough hotel will maintain your starter for you while you vacation.6 You could make your own starter using just flour, salt and water, or purchase a regional starter dough over the web. And you might decide the starter’s history doesn’t really matter - scientists have found the same distinct strains of Lactobacillus in San Francisco starter doughs as in bakeries across Europe.7

But is it real sourdough?

But while some bakers are fiercely proud of their traditional sourdough and treasured starter doughs, there is no legal definition of sourdough. It’s really the Lactobacillus which is key to creating sourdough, yet there is no official legislation stating a sourdough loaf has to contain any Lactobacillus.8

Though 30–50 % of European breads are produced using sourdough, industrially-produced sourdough uses dried starters rather than a spoon of sticky dough from a treasured pot.  Other ‘sourdough mimics’ are likely leavened using yeast, and artificially soured with additives. And  sourdough mimics may not have the time or microbes needed to break down the gluten in grains. Which means, if you are gluten-intolerant or avoiding high GI-foods, there is even more reason to care whether your sourdough is authentic or not.

Slow to produce, nurtured like a pet, is sourdough worth making the traditional way? Let us know what you think in the comments below!

References

  1. Capelle et al. (2012) “Historical and Social Aspects of Sourdough”
  2. Pontonio et al. (2017) “Sourdough authentication: quantitative PCR to detect the lactic acid bacterial microbiota in breads” Accessed 12 April 2019.
  3. Greco et al. (2011) “Safety for patients with celiac disease of baked goods made of wheat flour hydrolyzed during food processing” Accessed 12 April 2019.
  4. “Sourdough Hands: How Bakers And Bread Are A Microbial Match” National Public Radio. Accessed 12 April 2019.
  5. “Inside the World’s Only Sourdough Library” Atlas Obscura. Accessed 12 April 2019.
  6. “Inside Sweden’s secret hotel for sourdough obsessives.” The Local. Accessed 12 April 2019.
  7. Lhomme et al. (2016) “Sourdough microbial community dynamics: An analysis during French organic bread-making processes” Accessed 12 April 2019.
  8. Information Paper On Sourdough In Europe. Fedima. Accessed 12 April 2019.