Starch-Gluten and Wheat Derivatives as Functional Fortifiers of Sourdough Bread: Nutritional, Antioxidant and Quality Insights

Fortifying sourdough bread with functional ingredients is an effective strategy to enhance nutritional value, bioactive content, and sensory quality. In this study, the novel strain L. paracasei SP5 was incorporated into mother sponges together with trahanas (2% and 5% w/w) or delignified wheat bran (2% and 5% w/w) and the effects on sourdough bread functionality were evaluated. Sourdough breads supplemented with trahanas exhibited the highest lactic acid bacteria counts (up to 10.4 log cfu/g) and the strongest acidification (pH 4.25–4.32; TTA 9.1–9.8 mL NaOH), along with elevated lactic (2.50–2.53 g/kg) and acetic acid (2.76–3.11 g/kg) concentrations. These breads also showed enhanced total phenolic content (up to 112.1 mg GAE/100 g) and antioxidant activity (ABTS 221.5 mg TE/100 g; DPPH 5.0 µmol TE/g), as well as phytic acid degradation exceeding 91%, improving mineral bioavailability. Sourdough breads supplemented with wheat bran displayed moderate improvements in these parameters, while control breads had the lowest values. Sourdough breads supplemented with trahanas also demonstrated extended shelf-life. These results indicate that L. paracasei SP5 combined with nutrient-rich substrates effectively enhances sourdough bread quality and functionality.