Meet the Baker Behind the Loaves (podcast): Karl De Smedt, The Sourdough Librarian

When describing one’s desire to never stop learning about the art of sourdough bread baking terms like journey, adventure, and quest are often used. Each of them meaning something different to each individual baker based on how he or she goes about learning new baking skills and harnessing what drives their unique passion for sourdough baking. For example, I often describe my baking as a journey because my passion is driven by things like experimentation, ingredient research, and learning from fellow bakers that I meet as a result of sharing my baking experiences with the worldwise sourdough community. This week’s featured baker has chosen the term “quest” to describe his pursuit of sourdough knowledge and quality baking experiences. In its simplest form, a quest can be defined as “an act or instance of seeking” (Merriam Webster dictionary). In my opinion this definition may be a bit too general because while one can go on a quest to seek something for him or herself. A quest can take on a much deeper meaning when it is carried out on behalf of others.

More specifically, Karl De Smedt aka the sourdough librarian has dedicated himself to ensuring the future of sourdough baking and constantly learning more about each sourdough culture’s story and capabilities through his “Quest for Sourdough” and research at the Puratos World Heritage Sourdough Library. After interviewing him I excitedly and sincerely shared the following on Instagram . “One factor that I’ve cherished over my years as a blogger is that while I’ve never amassed a sizeable amount of followers etc, I’ve been able to meet and interview quite a few individuals who inspire me on many different levels. This morning I had the pleasure of meeting and interviewing one such individual, Karl De Smidt aka @the_sourdough_librarian. I found out that he is as much of a fermentation enthusiast as I am and values what it means to live a life that is defined by all that goes into truly “living food” and “living bread.” In other words, I found his passion, wealth of knowledge, and genuine personality to be inspiring, enlightening, and relateable on many levels.

So without further ado, it is may honor to present to you, Karl De Smedt of the Puratos World Heritage Sourdough Library.

The following topics were discussed during the course of this interview (podcast episode):

0:00-1:48 – Episode Intro – including one of the historical facts that I learned during this interview that blew my mind.

1:49-3:06 – Karl’s baking background before and after joining Puratos.

3:07-6:18 – History of the Puratos World Heritage Sourdough Library and its primary goals.

6:19-9:50 – Do sourdough starters in the Sourdough Library stay true to their original cultures and characteristics? and Plans to investigate this by revisiting their original sources.

9:51-12:00 – Lambic (wild) beer fermentation in Belgium – the unique wild yeast and bacteria present in each brewery and its surrounding area.

12:01-14:09 – Notable discoveries made so far at the Sourdough Library.

14:10-15:43 – Unique properties of lactobacillus sanfranciscensis, a lactic acid bacteria that was originally found in San Fransisco, but was later found in sourdough cultures all over the world.

Photo Credit: The Quest for Sourdough

15:44-17:53 – What Karl has gained from interacting with fellow bakers while on his “Quest for Sourdough.”

17:54-21:16 – An outsider’s view on the prevalance and history of sourdough in the United States versus that of European countries.

21:17-23:07 – Were classic French and Italian breads originally made with sourdough?

23:08-26:53- Why countries with histories of baking rye breads have longer stretches of uninterrupted years of sourdough being their primary bread leavening agent? and The science of baking an evenly baked loaf of German sourdough rye bread.

26:54-29:06 – What effects does rye flour truly have on sourdough starters that are not performing (fermenting) as expected?

29:08-31:20 – Sourdough culture in Belgium and its relation to well known American sourdough bakers.

31:21-33:20 – Countries that bake using sourdough, but purposely avoid sourness in their breads. Also, Karl’s experiences with sourdough in China and Japan.

Photo Credit: The Quest for Sourdough

33:21-35:26 – Notable friendships that Karl has formed since officially launching his “quest for sourdough.”

35:27-40:52 – Karl’s perspective on the terms “living bread” and “living food” and how it relates to the history of bread and fermentation. – What came first beer or bread?

40:53-43:21 – What’s being worked on now at the Sourdough Library? and What are some future plans for experiments (sourdough culture analysis)?

43:22-44:56 – The scientific study of sourdough’s effects on grain digestibility at the University of Bozen/Bolzano in Italy using starters from the library.

44:57-47:08 – Getting in touch with Karl and keeping up with the Sourdough Library’s activities…What are the benefits of registering your sourdough starter on

47:09-48:30 – Parting remarks and episode outro.


About Barry W

Israel (formerly NJ) based sourdough baker and fermentation enthusiasts sharing his baking, fermenting, cooking, and brewing adventures on
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