Durum Wheat Milling By-Product Valorization Through the Production of Fermented Freeze-Dried Bioingredients for Breadmaking

The aim of this study was to valorize durum wheat milling by-products through fermentation in order to obtain fermented bioingredients acting as sourdough in yeast-leavened bread and improving its nutritional and technological properties. Wheat bran or germ flours were fermented using the Lactiplantibacillus plantarum ITM21B strain (log10 5.00 CFU/g, 14 h at 37 °C), thus obtaining Bio21B-B or Bio21B-G (at dough yield DY500 and DY300, respectively). After fermentation, both bioingredients were enriched in lactic acid, while a significant reduction of the total protein content (by 87% and 95% for Bio21B-B and Bio21B-G, respectively) was observed. The germ-based bioingredient was also enriched in total free amino acids and L-glutamate. The preliminary incorporation of bioingredients in bread formulation at a wheat flour replacement level in the range 4–7% highlighted the need to increase the integration level to fortify the final product with bioactive compounds. To this aim, freeze-dried fermented bioingredients were incorporated in yeast-leavened bread formulations by replacing 24% of wheat flour. Nutritional characterization of breads indicated a higher concentration of organic acids, amino acids (L-glutamate, alanine, aspartate, glycine, and arginine), and total protein content in breads prepared with the bioingredient compared to the respective control bread containing unfermented flour and to the standard bread. The evaluation of bread texture highlighted a positive impact of fermentation in fermented germ-based bread, showing a reduction of hardness and improvement of chewiness and volume in comparison with its relevant control. Further studies are needed to optimize bread formulation and improve technological characteristics of baked products including wheat by-products.