Valorisation of underutilised leaf biomass as a sustainable source of protein through nutritional profiling

The rising global population demands a twofold increase in food production by 2050, necessitating sustainable and nutritionally adequate protein sources from underutilised plant biomasses with high nutritional potential. The present study provides a comprehensive and comparative nutritional characterisation of three underutilised leaf biomasses—Moringa oleifera, Amaranthus viridis, and Medicago sativa—by integrating proximate composition, mineral content, amino acid profiling, anti-nutritional factors, IVPD, and multivariate statistical analysis. The findings revealed that the leaves analysed in this study exhibited statistically significant variability (p < 0.001) in nutritional quality, with Amaranthus (29.73%) and Moringa (27.24%) demonstrating high protein content and superior digestibility. Mineral profiling revealed that Moringa oleifera is a rich source of essential micronutrients, particularly iron (20.13 mg 100 g⁻¹) and zinc (19.34 mg 100 g⁻¹). In contrast, anti-nutritional assessment demonstrated species-specific accumulation patterns that may affect nutrient bioavailability. Furthermore, multivariate analysis revealed a strong positive correlation between protein content and digestibility (r = 0.99), accompanied by the concurrent presence of certain anti-nutrients, underscoring the complex nutritional and functional interactions within these leaf biomasses. The present study advances knowledge by providing comparative evidence on the protein digestibility and nutritional quality of Amaranthus viridis and Medicago sativa leaves, which remain relatively underexplored as potential protein-rich leaf biomasses. Furthermore, it provides integrated insights by linking nutritional quality with protein digestibility and anti-nutritional components that influence protein bioavailability. This integrated evaluation provides a strong basis for the valorisation of these leaf biomasses as sustainable protein sources for functional food and nutritional applications.