Development of Functional Gluten-Free Sourdough Bread Enriched with Enzyme-Treated Broccoli By-Products

Broccoli by-products represent an underutilized source of dietary fiber and bioactive compounds with potential as functional food ingredients. This study evaluated the effect of enzymatic treatment with Viscozyme® L on broccoli by-products and their incorporation into gluten-free (GF) sourdough breads. Three GF bread formulations were developed: a control bread (BCT), a bread enriched with untreated broccoli by-products (BBC), and a bread enriched with enzymatically treated broccoli by-products (BBE), using a commercial GF bread (COM) as reference. Nutritional composition, antioxidant activity, starch digestibility, and sensory characteristics were evaluated. The incorporation of broccoli by-products significantly improved protein, total dietary fiber, and antioxidant activity compared with COM, with all reformulated breads meeting the EU “high fiber” claim. Enzymatic treatment with Viscozyme® L further enhanced these properties, with BBE reaching 2.66 g 100 g−1 soluble dietary fiber and 13.51 µM TE g−1 in FRAP, while exhibiting the highest slowly digestible starch content (20.39 g 100 g−1), suggesting a potentially more favorable starch digestibility profile. Sensory evaluation confirmed that these nutritional improvements were achieved without significantly compromising consumer acceptability. Overall, Viscozyme® L-treated broccoli by-products represent a sustainable, clean-label ingredient for nutritionally enhanced GF bakery products, supporting agri-food by-product valorization within a circular economy framework.