Oat sourdough fermentation enhanced β-glucan viscosity and extractability from wholegrain oat bread in an in vitro gastrointestinal model

Sourdough fermentation has been demonstrated to enhance the texture, sensory and nutritional properties of wheat- and rye-based bread. However, its use in wholegrain oat bread is not well known, especially its impact on altering the physiological functionality of β-glucan. This study aimed to design fermentation conditions for oat sourdough to enhance the β-glucan functionality in wholegrain oat bread using two types of germinated oats as a source of enzymes, showing different β-glucanase activity. Two sourdoughs, fermented by an association of Lactiplantibacillus plantarum and Fructilactobacillus sanfranciscensis strains, have been obtained: one fermented with oat malt (OM) and the other with sprouted oat grains (SPO). Sourdough was added to the bread as 30% of the total dough weight (61% of flour weight). An in vitro gastrointestinal simulation model was used to assess the physiological functionality of β-glucan in the breads. The use of the two germinated materials induced a different degradation of β-glucan (from 1,060.3×10 3 g/mol to 681.7×10 3 g/mol with SPO vs. 117.4×10 3 g/mol with OM). The addition of sourdough with sprouted oats made the bread softer and increased its volume. The extracts obtained after in vitro digestion from this bread showed high value of viscosity and the highest β-glucan extractability, indicating an increased physiological functionality of β-glucan. This study demonstrated the potential of sourdough fermentation to modulate β-glucan degradation and improve the physiological functionality of oat bread.