What yogurt and sourdough bread have in common, and how the key starter ingredients for both can be the infinite source for future batches.
My mom absolutely loves her friend’s Indian yogurt and asked for the recipe. She was handed a tiny container of old yogurt with a smile and simple instructions: add this to fresh plain yogurt. At first, my mother was confused - why would she want old yogurt...wouldn’t it go bad eventually?
What my mom didn’t know was that she had been handed an infinite supply of yogurt-making material. Mix this old yogurt with some plain new yogurt, and eventually the new yogurt will magically taste like the old yogurt. Want to make more? Repeat.
Making new yogurt from old yogurt starter is the work of microorganisms, and it is also applicable to making sourdough bread.
First of all, let’s be clear about what sourdough bread is. While many bread recipes prescribe baker’s yeast as a leavening agent, authentic sourdough recipes call for a sourdough starter.
Unlike other types of leavening agents, sourdough starter is a fermented mix of flour and water that you can make at home. Now, throw this starter, some flour, water, and salt into the oven, and you will get bread with richer flavors than a bread made with commercial baker’s yeast. The difference is this goopy and pungent sourdough starter.
If we were to examine this starter with a powerful microscope, we would see a burgeoning community of microorganisms like lactic acid bacteria (LAB) and wild yeasts. These microorganisms come naturally from the flour, and they are continually cared for and cultured by the baker.
All the microorganisms feed on the flour’s sugars and release bubbles of carbon dioxide gas through a biological process called fermentation. These pockets of gas ensure a light and fluffy bread. LAB specifically secrete the “sour” acids like acetic acid and lactic acid which flavor the bread. If your starter bubbles and smells, the sourdough fermentation process is probably working.
Properly cared for, a jar of sourdough starter can be passed down generations. However, a common misconception is that sourdough breads made with older starters taste better. While a starter’s taste improves initially, the taste is more dependent on the makeup of the microbial community rather than the starter’s age. Different flour and water from different environments create different microbial communities! In fact, food scientists from North Carolina State University began the “Sourdough Project”. They investigated whether geography, climate, and even the baker’s gender (women have more LAB on their bodies than men!) affect the microbial communities and taste of sourdough bread. It turns out, the bacteria living on the skin of baker’s hands as well as the location of where the starter was made did affect the microbial makeup of the dough starter.
It sounds cheesy, but maybe it’s also the love and care that goes into passed down starter from family and friends that impact taste. Based on the yogurt her friend made and passed down, my mom thinks so.
Link to the Sourdough Project
Sources
This was a very interesting article. I loved it! Keep up the good work Lucy.