Protein fortification of semolina bread with dry-fractionated lentil protein: Techno-functional and sensory implications

Semolina bread provides high energy content but relatively low protein and dietary fiber levels, representing a nutritional limitation in cereal-based diets. In the context of the growing demand for nutritionally balanced and sustainable foods, this study investigated the effects of enriching semi-whole wheat semolina bread rolls with dry-fractionated yellow lentil protein (fYLPF) at substitution levels ranging from 10 to 40 %, focusing on nutritional, technological, rheological, and functional properties. The fYLPF was characterized by high protein (53.97 %), dietary fiber (11.33 %), and carotenoid content (29.36 mg/kg), confirming its suitability as a sustainable plant-based ingredient. Protein fortification markedly modified dough rheology, leading to increased storage and loss moduli, higher apparent viscosity, and a reduced tan delta, indicative of a solid-like viscoelastic behavior. In the final products, protein and dietary fiber contents increased markedly (up to 16.37 % and 4.38 %, respectively), enabling nutrition claims according to Regulation (EC) No 1924/2006, while carbohydrate content and predicted glycemic index were significantly reduced. Enriched bread rolls also exhibited higher total phenolic content, antioxidant activity, carotenoid levels, free amino acids, and improved in vitro protein digestibility. Protein inclusion influenced technological, textural, and sensory attributes, with increased hardness and chewiness, reduced specific volume, and sensory profiles characterized by more pronounced legume and acidic notes, as well as increased perception of astringency and bitterness at higher substitution levels. Overall, the results suggest that dry-fractionated lentil protein is an effective ingredient for enhancing nutritional quality and protein content while reducing glycemic impact, maintaining acceptable technofunctional performance, particularly at moderate inclusion levels.