What wheat fibers do to sourdough bread: VUB research reveals hidden flavor makers

Sourdough bread is making a major comeback. It’s praised for being pure, nutritious, and full of character. But what exactly makes this bread so special? In his PhD at the Vrije Universiteit Brussel (VUB), researcher Víctor González Alonso delved deep into the heart of the fermentation process — and discovered how wheat fibers influence not only the texture but also the flavor of bread.

At the center of his research are arabinoxylans (AX), dietary fibers naturally present in wheat. They come in two forms: soluble fibers (WE-AX), which benefit the dough, and insoluble fibers (WU-AX), which can reduce bread quality. Using modern DNA sequencing and metabolite analysis, González Alonso investigated how microorganisms in sourdough respond to these fibers.

His findings challenge some long-standing assumptions. The fiber content itself barely disrupted the development of the sourdough, but the enzymes naturally present in wheat turned out to play a much greater role than expected. Under the acidic conditions of fermentation, these enzymes partially broke down the fibers, influencing both the digestibility and texture of the final bread.

González Alonso also discovered that certain bacteria create new aromas. For example, Lactococcus lactis adds a buttery note, while Limosilactobacillus fermentum introduces a subtle sweet touch.

The results were made tangible, too: the team baked pilot-scale sourdough loaves using fiber-rich wheat. The verdict? Breads that were not only more nutritious but also richer in flavor.

“Sourdough is a beautiful interplay of biology and craftsmanship,” González Alonso concludes. “We now know that fibers play a much greater role in that process than we ever imagined.”