Unlocking the functional potential of broccoli protein: A comparative study of deep eutectic solvent and traditional...

To address the growing shortage of protein resources, plant-derived proteins have become a major focus in food research. Broccoli, containing approximately 25% protein on a dry-weight basis, represents a promising yet underexplored source due to limited understanding of its extractability and functional properties. In this study, we compared the protein composition and functionality of broccoli protein isolates (BPI) obtained using alkali-acid isolation (ALK-BPI) and deep eutectic solvent extraction (DES-BPI). A total of 3639, 3383, and 3556 proteins were identified in broccoli powder, DES-BPI, and ALK-BPI, respectively. Compared with ALK-BPI, DES-BPI preserved a broader range of proteins and exhibited higher similarity to unprocessed broccoli, indicating that DES extraction maintains the native protein profile. DES-BPI was particularly enriched in ribosomal and chloroplast-associated proteins, likely due to hydrogen-bonding interactions between proteins and the solvent matrix. Moreover, DES-BPI showed enrichment of stress-response proteins, which significantly contributed to its higher antioxidant activity compared with ALK-BPI (T-AOC: 1.20- fold, DPPH: 1.34- fold, ABTS: 1.18- fold). Random forest analysis identified phosphoglycerate kinase and glutathione reductase as the major contributors to antioxidant capacity. Collectively, these findings indicate that DES extraction not only enhances protein recovery but also preserves proteins with superior nutritional and functional potential. This highlights broccoli as a valuable plant protein source and provides new insights into DES as a mild and efficient approach for producing functional foods and sustainable protein ingredients.