Sourdough science

Do you still have the starter you created when everyone was making sourdough bread in the pandemic? I’m sad to report that my starter died an ignoble death at the back of our basement refrigerator. I’m a serial starter killer, but I might have to try again, because nothing you can buy can replicate the flavor of a true sourdough bread. But why it that? Scientists are coming closer to answer that question, as they unlock the secrets of sourdough.

Researchers in Brussels analyzed fibers in wheat called arabinoxylans, which come in two forms: “water-extractable, which have a positive or neutral effect on dough, and water-unextractable, which can actually decrease bread quality.” The findings of this research show that these fibers affect the growth of microorganisms in the mix of enzymes and bacteria produced by the fermentation process. Previously, it was assumed that the bacteria were responsible for transforming some of the water-extractable fibers into the water-unextractable types. However, using advanced DNA techniques and metabolite analysis, doctoral researcher Víctor González Alonso discovered that the change was triggered by enzymes inside the wheat itself.

González Alonso also made findings about the flavor of sourdough. He identified bacteria responsible for some of the taste qualities most appreciated by sourdough bread aficionados. Lactococcus lactis helped form buttery aromas, while Limosilactobacillus fermentum produced sugar alcohols that lend sweetness to the bread.