Molecular determinants of protein foamability and foam stability revealed by hydrogen/deuterium exchange MALDI mass...

Foam stability in food systems is governed by molecular processes that occur at the air-liquid interface; however, the intrinsic protein properties governing macroscopic foam performance remain insufficiently understood. In this study, we applied a high-throughput hydrogen/deuterium exchange matrix-assisted laser desorption/ionization mass spectrometry (HDX MALDI-MS) approach to quantify protein structural flexibility and investigated its relationship with foam properties. Four model proteins differing in molecular size, structural stability, and surface hydrophobicity were characterized systematically. Correlation analysis revealed that foamability showed a strong positive relationship with surface hydrophobicity, indicating that foam formation is primarily controlled by adsorption kinetics. Foam stability strongly correlated with the amount of exchanged hydrogen of the slowly exchanging backbone amide HDX population, which reflects structural flexibility within protected regions of the protein. These findings demonstrate a clear association between HDX-derived structural flexibility and foam stabilization performance. Importantly, the HDX-based analytical approach provides quantitative information on protein structural flexibility that is associated with foam stability. In combination with conventional interfacial characterization, this approach may provide deeper and more precise insight into the mechanisms of protein-mediated foam stabilization and offer a foundation for the rational screening and design of proteins with enhanced foaming performance for food applications.