pH-shifting extraction reveals conformation-dependent flavor binding to sea cucumber collagen proteins

Sea cucumber collagen fibers (SCCF) are important nutritional and functional resources in aquatic foods, yet their interactions with flavor compounds remain insufficiently understood. This study innovatively applied pH-shifting extraction to isolate sea cucumber collagen fiber proteins extracted at alkaline (ALP), neutral (NP), and acidic pH (ACP), revealing conformation-dependent mechanisms in flavor binding. Key amino acids (Glu, Gly, Phe) were identified as crucial for structural stability and binding potential. Multi-spectroscopic analyses demonstrated that flavor interaction induced significant conformational changes: a reduction in α-helix and β-sheet content, with an increase in β-turns and random coils. FL and FTIR spectra confirmed that hydrogen bonding and hydrophobic interactions were the dominant forces driving complex formation. The molecular weight distribution and amino acid composition of the proteins varied substantially with extraction pH, directly influencing their distinct flavor-binding capacities. These findings provide a novel strategy for optimizing flavor retention in seafood by tailoring protein extraction conditions. • pH-shifting effectively fractionated sea cucumber collagen into ALP, NP, and ACP. • Flavor binding capacity varied with protein isoelectric point and compound structure. • Spectroscopic analyses revealed flavor-induced secondary and tertiary rearrangements. • Findings provide mechanistic insights for improving flavor stability in seafood proteins.