Sourdough. Pasta madre. Surdeg. Masa madre. Sauerteig. Μεταλευτής. Levain… of course, levain.
Something acidic (sour, sauer, sur), something that can regenerate itself (madre, mother), and something that can rise (levain, leaven). These are terms found in the languages of some of the cultures that have traditionally used this mixture of wild yeasts and lactobacilli to ferment flour and make leavened bread.
There are several proverbs that warn us to not let a lover know too much about the loved one, lest the information break the spell. Applying this old-school wisdom to my passion for sourdough, I did not mind knowing as little as possible about my creature and preferred an instinctive approach when it came to bread making, even though I was earning my living as a scientist. I guess sourdough baking is, for me as for many others, a way of reconnecting with mother earth.
So why be pedantic about it?
One good reason for unveiling the magic behind sourdough fermentation is consistency.
As sourdough bakers, we have all faced the enigma: “Why did this loaf come out ugly, sad, and flat while last week’s loaf was just gorgeous?” Some days, my sourdough starter tripled its volume in a few hours, and on others, it hardly doubled. Thus, quite reluctantly, I began to seek for answers. I learned about the impact of the acidity of the sourdough culture and the effect of the external temperature on my starter. I became accustomed to the terms homofermentative and heterofermentative lactobacilli. But I was still feeling that I was missing some pieces of the puzzle and that I needed help to move forward.
To find the answers to my remaining questions, I reached out to one of the most acclaimed masters of sourdough baking, Ian McMillan Lowe. He is a baker with a substantial bread baking background combined with a deep interest in the microbiological aspects of natural fermentation.
Ian has worked for chefs Mario Batali, Thomas Keller, Sam Mason, Gordon Ramsay, and Chika Tillman in New York City, and for Daniel Chirico in Melbourne, Australia. In 2013, he opened his “neighborhood bakery,” Apiece, in Launceston, Tasmania. Apiece specializes in naturally leavened bread and its Instagram feed is one of the most followed among sourdough baking enthusiasts. Ian is also the co-founder of BreadEd, an artisan bakers’ conference focusing on local grain economies, now heading into its fourth year.
In his spare time, Ian reads everything ever published on sourdough fermentation, continuously updating his knowledge as new scientific articles on the topic are published. Most importantly, he does not just read; he applies what he learns to his baking, turning his bakery into a permanent bread lab that produces delectable experiments.
How did you first become interested in natural fermentation?
I grew up in the suburbs of American cities like Houston, Phoenix, Wichita, and Dallas, where the food you eat outside your home is, almost without exception, the result of an industrial process. So, from a young age, I had an intense desire for “real” food, partly because it was so foreign to what I knew. My interest in natural fermentation, then, is born of a desire for simple, pure and “authentic” foods. I am a disciple of bread, as bread is my favorite food.
Natural fermentation is still the norm in lesser developed countries, more out of necessity than ideology. In rural Africa and Southeast Asia, for example, there are traditional beers still being made using whichever local grains happen to be available, like sorghum, millet, or maize. The resulting beer is naturally fermented, low-alcohol, unpasteurized, unfiltered, and ultimately has a short shelf-life. What’s more, these beers are closer to sourdough bread in their microbial communities than they are to “first-world” beers, and arguably with greater health benefits.
What are, in your opinion, the advantages of this type of fermentation compared to that based on commercial yeast?
First, there are the obvious benefits, repeated in baking literature: extended shelf-life, better texture in the final product, and an increased nutritional profile.
But, for me, flavor matters above all else.
And in this sense, there’s no comparison: I’ve never had a yeasted product that tastes better than its sourdough counterpart–a conclusion similarly found in nearly every study using controlled blind tasting panels.
What are the main differences between the two types of fermentation, natural and yeast-based?
There are three primary differences. The first has to do with an overall mindset, the implications of which are difficult to elucidate. The use of industrial yeast strains embodies the reductive, illusory ideal that humans have some control over nature. Of course, it’s just a gross simplification for convenience’s sake.
Yeast manufacturers produce a highly specific subset of yeast strains for use in almost every biotechnological application: beer, bioethanol, bread, the production of medically-related compounds, sake, wine. Most of these strains are selected for only one or two reasons. Saccharomyces strains used in bread production, for instance, have been chosen to maximize carbon dioxide output and for their ability to survive whichever packaging process is used. That’s it. It’s hard to quantify the long-term environmental or health costs, which are likely both immense.
The second corollary stems from the first. The industrial process allows for the concentration and use of cell numbers that are not achievable in nature. For example, to attain a yeast cell population comparable to that you would find in a dough made of 1% fresh yeast to one kilogram of flour (a standard rate of inoculation in classic lean dough formulas), the sourdough baker would have to preferment approximately 16 kg of flour.