Evaluation of Oat Okara Sourdough for Its Potential Uses in Bread Making

The growing over-75 population has increased the demand for functional foods tailored to the nutritional needs of the elderly. Within the AURA project, an innovative oat okara sourdough was developed to produce bread with enhanced nutritional and functional properties. Breads were produced using oat okara sourdough, oat sourdough, and wheat sourdough for comparison. All samples were subjected to microbiological, physical-chemical, technological, and metabolomic analysis. In addition, bread digestibility was evaluated. The results showed that oat okara flour is an excellent fermentable substrate, yielding sourdoughs with high counts of lactic acid bacteria and yeasts. The breads made with oat okara and oats were softer and brownish due to the oat presence and higher relative yeast. Moreover, oat okara bread exhibited a lower proportion of rapidly digestible starch (RDS) and a higher proportion of slowly digestible starch (SDS), suggesting potential benefits for post-prandial glycaemic control. Metabolomic profiling highlighted lipids, particularly steroidal glycosides (saponins) and fatty acyls, as discriminant metabolites in fermented samples, suggesting enhancement of bioactive compounds through sourdough fermentation. Overall, the use of oat okara in sourdough represents a sustainable approach to upcycle agro-industrial by-products while producing nutritionally valuable bakery products aligned with circular economy principles.