Multidimensional Evaluation of Local Rye Bread Fortified with Whey as a Model for Food Waste Valorization: From Recipe Development to Consumer Acceptance

The growing demand for functional and sustainable foods has driven food innovation, enhancing its nutritional value. This study aimed to develop a nutritious bread using local rye from the Trás-os-Montes region of Portugal and incorporating whey, a by-product of the dairy industry, as a replacement for water. Three bread formulations were tested: a traditional recipe with 37.5% rye flour and water (Control—CTR); the same recipe using whey instead of water (Rye Whey—RW); and a formulation with 100% local rye and whey replacing water (Full Rye Whey—FRW). Nutritional composition was assessed, including moisture, ash, protein, dietary fiber, sodium, potassium, lipids, and carbohydrates. Sensory analysis included both quantitative descriptive analysis and consumer acceptance testing. Microbiological quality was also evaluated. Whey-containing samples showed lower moisture and increased levels of ash, lipids, carbohydrates, and potassium. RW had the highest protein content (6.54 ± 0.28 g/100 g, p < 0.05), while FRW exhibited the highest dietary fiber (6.96 ± 0.15 g/100 g, p < 0.05). RW demonstrated a balanced nutritional and sensory profile, with high consumer acceptance. Overall, the combination of local rye and whey presents a promising strategy for producing nutritious bread while valorizing local agricultural resources and dairy by-products. These findings support sustainable food production practices and contribute to circular economy approaches.