From Germinated Pseudocereals to Functionalized Bread: The Role of the Food Matrix in Protein and Phenolic Bioaccessibility

Abstract

Despite the well-documented nutritional benefits of germinated pseudocereals, whether these benefits are preserved following bread incorporation remains unexplored. Bread incorporating germinated quinoa, amaranth, and buckwheat at 15% and 30% substitution was evaluated alongside the germinated materials using rheological, chemical, and in vitro digestion simulation methods. Except for amaranth, all formulations demonstrated lower hardness than the whole wheat control. Overall, quinoa and buckwheat breads yielded acceptable rheological quality. Germinated buckwheat exhibited the highest protein content (33.38 g/100 g DW); however, the protein contribution in incorporated bread remained below theoretically expected values. Germinated quinoa (61.5%) showed the highest in vitro protein bioaccessibility, and protein digestibility decreased with increasing substitution levels. Despite the lowest quantitative protein contribution, buckwheat-incorporated bread exhibited the highest protein digestibility among all formulations. Furthermore, buckwheat showed the highest phenolic content (1988 mg GAE/100 g) and flavonoid bioaccessibility (92.7%); however, these advantages were not reflected in the incorporated bread products. Germination-induced improvements do not necessarily translate into enhanced nutrient bioaccessibility in the final bread product. These findings are consistent with a critical role of the food matrix and suggest that germinated quinoa demonstrates the most consistent overall performance, while buckwheat shows advantages in protein digestibility and flavonoid bioaccessibility.