• Ezeja Enechojo Peace
  Department of Nutrition and Dietetic, Faculty of Agriculture, University of Nigeria, Nsukka
  Department of Chemistry, Faculty of Sciences, Rev. Fr. Moses Orshio Adasu University, Makurdi, Nigeria
  




• Adie Peter Agorye
  Department of Chemistry, Faculty of Sciences, Rev. Fr. Moses Orshio Adasu University, Makurdi, Nigeria
  




• Ogo Ogo
  Department of Biochemistry, College of Health Sciences, Rev. Fr. Moses Orshio Adasu University, Makurdi, Nigeria
  

African locust bean (Parkia biglobosa) is an underutilised West African legume consumed mainly as a fermented condiment, and its potential as a source of plant protein isolate remains largely unexplored. Conventional alkaline solubilisation-isoelectric precipitation exposes protein to harsh pH conditions that can degrade amino acids and reduce protein quality, prompting interest in greener alternatives such as natural deep eutectic solvents (NADES) and ultrasound-assisted extraction. This study characterised the proximate composition of African locust bean flour and comparatively evaluated the amino acid profile and anti-nutrient content of protein isolates recovered by three methods: conventional alkaline solubilisation-isoelectric precipitation (ALK), natural deep eutectic solvent extraction (NDS), and ultrasound-assisted NADES extraction (ULT) methods. African locust bean seeds were processed into flour and protein was extracted by the three methods. Proximate composition of the seed flour, amino acid profiles and antinutrient contents of the isolated proteins were determined using standard methods, and data were analysed using SPSS version 23, with significance accepted at p < 0.05. African locust bean seed flour contained 28.67% protein, 28.23% fat, 8.40% fibre, 6.34% moisture, 1.94% ash and 26.43% carbohydrate. Total amino acid content was highest in NDS (31.42 g/100 g), followed by ULT (26.19 g/100 g) and ALK (25.14 g/100 g), and anti-nutrient levels declined substantially from flour to isolates, with tannins and trypsin inhibitor undetectable in most isolates. Natural deep eutectic solvent extraction produced protein isolates with the highest and best-preserved amino acid content alongside the most comprehensive anti-nutrient reduction, positioning it as a promising green alternative to conventional alkaline extraction for valorising African locust bean as a plant protein source.