Hybrid Fractionation of Cowpea: Combining Dry and Wet Routes to Produce Versatile Protein Ingredients

Cowpea (Vigna unguiculata L.) is an underutilized protein-rich pulse with strong potential to diversify the alternative protein market, particularly through sustainable fractionation strategies. However, comparative insights into how dry and hybrid routes influence protein structure, functionality, and nutritional quality within the same processing stream remain limited. This study evaluated the nutritional, morphological, and techno-functional properties of ingredients recovered via dry and hybrid (dry-wet) processes. Dry fractionation (milling and air classification) yielded a cowpea protein concentrate (CPC) with 47.5% yield and 54.6 g·100 g^-1 protein (d.b.). CPC served as feedstock for wet extraction, producing a cowpea protein isolate (CPI) with a 45.0% process yield and 87.5 g·100 g^-1 protein (d.b.). The hybrid route increased protein purity compared to dry processing while reducing solvent demand (water and pH-adjusting solutions) per unit of protein relative to conventional wet extraction of whole flour. Both ingredients mainly consisted of glutamic acid, aspartic acid, leucine, and lysine. The amino acid score (AAS) met FAO/WHO requirements, except for sulfur-containing amino acids, with in vitro protein digestibility-corrected AAS of 66% (CPC) and 70% (CPI). Soaking (CPC-S) markedly reduced tannins, phytates, and ash content through leaching. CPI exhibited higher solubility at alkaline pH and improved emulsifying, foaming, and water-/oil-holding capacities than CPC. Structural analyses indicated that the hybrid process produced a more homogeneous protein-rich matrix with signs of aggregation and molecular rearrangement. In contrast, dry-fractionated ingredients retained heterogeneous structures associated with protein-carbohydrate interactions. Overall, the hybrid route efficiently produced a high-purity CPI, with improved functionality, and provided a promising route for developing high-value cowpea-derived ingredients for plant-based food applications. PRACTICAL APPLICATIONS: This study demonstrates an efficient strategy for converting cowpeas into high-value protein ingredients using a combined dry and wet fractionation approach. By removing starch- and fiber-rich components during the initial dry fractionation step, the process generates a protein-enriched fraction that facilitates downstream extraction and can reduce the intensity of aqueous processing compared to conventional wet extraction from whole flour. The resulting ingredients exhibit enhanced nutritional quality and improved techno-functional performance, including higher solubility, emulsifying capacity, and foaming properties. These attributes support their use across diverse food applications, including plant-based beverages, meat analogs, bakery products, and nutritional formulations. Overall, this approach expands the use of cowpea as a versatile, sustainable, and competitive alternative protein source for contemporary food systems.