Why sourdough went viral

By Josie Delap

Shortly before the world shut down in response to covid-19 someone tweeted that a “sourdough starter is a Tamagotchi for people in their 30s”. The analogy, no doubt irritating to diligent bakers, is apt. Like the diminutive digital pets, you have to regularly feed your sourdough starter – the gloop of wild yeast and accompanying bacteria used to leaven this type of bread. You can overfeed both. Though you can leave your starter to slumber in the fridge for a while, ignore it for too long and, like a Tamagotchi, it will perish. In the (currently unimaginable) event that you jet off on a long holiday, it is now possible to check your starter into a sourdough hotel, which will lavish care on it until you return.

No one country can lay claim to sourdough, but the Egyptians may have been the first to bake bread raised with wild yeast. In 2019 Seamus Blackney, a scientist who became a video-game designer, baked a loaf using a starter based on a 4,500-year-old yeast from Egypt. From the Middle East it spread north, through Europe and beyond. Each sourdough starter varies just slightly from one to the next, depending on the micro-organisms in the air, flour and water where it was made, and those on the hands of the mixer. Blackney used yeast from the Puratos Sourdough Library in Belgium – mission statement: “to preserve the biodiversity of leaven agents” – which has more than 90 starters in its vaults, from 25 countries. Most are from Europe. In the northern reaches of the continent sourdough is often made with 100% rye flour. Elsewhere lighter sourdoughs are more common. Some are protected by European regulations, such as Italy’s pane di Altamura, which is made with semolina flour, and Spain’s pan de Cea. These must be leavened with wild yeast.