Karl De Smedt’s official title at Belgium-based Puratos is communication and training manager, sourdough and grains.

But De Smedt is more widely known by a title that has become a huge hit on social media: The Sourdough Librarian. His popularity is due not only to the catchy name, but also to the fact that he is the only full-time sourdough librarian in the world.

There’s nothing gimmicky about De Smedt or his handle. At the Puratos Center for Bread Flavour, De Smedt oversees a collection of living sourdough starters that plays a vital role in preserving the bread’s past and present and ensuring its future.

Puratos first hatched the idea for a library in 1989. When De Smedt joined the company, in 1994, it was the first time he had ever tried sourdough.

“It was an epiphany,” he says. “I thought, ‘My God, what is happening here?’ I didn’t understand what it was.”

Puratos’s experiment ramped up significantly in 1997, when the company started collaborating with Marco Gobbetti, one of the leading authorities on sourdough fermentation in the world. The partnership began with a study of Italian sourdoughs — 18 breads from 18 different patisseries. At the time, no one thought the enterprise would turn into the library De Smedt oversees today.

Then a colleague got wind of what was happening.

“He heard we were collecting sourdoughs, and he started telling us about starters in Greece that were made with basil leaves, starters in Hungary that were made with grapes.”

They also learned about a baker who used chickpeas as the fermentation for ka’ak bread. His kids didn’t like the smell, so when they took over the bakery, they stopped making it. The baker came to Puratos with a plea: make a record of my recipe before it disappears.

Another time, on a visit to a famous sourdough bakery in Chicago, De Smedt and his colleagues were shocked to find out that on the site of the bakery there now stood a clothing store.

Those stories continued to multiply, and before they knew it, Puratos had 43 sourdoughs in its collection.

“We thought, if these bakeries are disappearing, we should do something to save their sourdoughs,” De Smedt says.

The library — walls of refrigerators kept at 4 degrees centigrade — currently contains 128 living sourdoughs. The library was not created for commercial purposes, but it does help bakeries that, for instance, want to analyze why the sourdoughs created in their different facilities have inconsistencies. Or maybe a company takes a sourdough out of production but doesn’t want to lose it forever, in case it decides to bring it back at a later date — the Puratos library becomes its home.