Green Extraction Technologies for Sustainable Plant Protein Recovery: Mechanisms, Functional Properties, and Industrial Applications with Emphasis on African Locust Bean

Abstract

Sustainable plant-protein production requires extraction processes that reduce resource use while preserving protein functionality. This review evaluates natural deep eutectic solvent (NADES) extraction, ultrasound-assisted extraction (UAE), and their integration, with emphasis on the underutilized African locust bean, Parkia biglobosa. A structured literature search was conducted in Scopus, Web of Science, PubMed/MEDLINE, ScienceDirect, and Google Scholar for literature published from January 2000 to July 2026, with emphasis on 2014–2026 studies. Evidence was synthesized narratively because the retrieved studies used heterogeneous matrices, extraction conditions, and analytical methods. Across plant-protein matrices, reported protein recovery was approximately 60–85% for NADES and 72–88% for integrated UAE–NADES systems, with generally improved solubility, emulsifying activity, foaming, and in vitro digestibility compared with conventional alkaline extraction–isoelectric precipitation (AE-IP). P. biglobosa contains approximately 25–40% crude protein and has a useful amino-acid profile, but direct species-specific experimental evidence for NADES and UAE remains limited. Green extraction technologies show promise for sustainable plant-protein recovery, but their performance cannot yet be assumed for P. biglobosa from evidence generated in other species. Direct optimization, functional characterization, safety assessment, and techno-economic evaluation of P. biglobosa are therefore priorities.