Structural evolution of β-lactoglobulin under intensified magnetic fields

This study investigates the structural and functional changes of β-lactoglobulin (β-LG) under incremental magnetic fields (IMF: 5, 10, 15, 20 T). Multi-scale characterization reveals four stages of conformational transition: contraction (5 T), folded compaction (10 T), aggregation/refolding (15 T), and unfolding/etching (20 T). The magnetic field was found to induce ordering of the secondary structure and promote oxidation reactions among CC, C-O-C, and O-C=O groups, thereby enhancing the crystallinity, emulsifying properties, and freeze-thaw stability of β-LG. Notably, at 10 T, the particle size reached a minimum of 67.46 ± 2.33 μm, representing a 32.23 % reduction (p < 0.05). The secondary structure showed increased order, with α-helix and β-sheet contents of 7.45 % and 58.74 %, respectively. Functional properties were optimized at 10 T: emulsifying activity increased to 10.26 m²/g (a 34.82 % improvement) and emulsifying stability to 81.70 % (a 72.04 % improvement), while freeze-thaw water precipitation was reduced by 15.4 %. These results fully demonstrate that IMF can precisely restructure β-LG through oxidative folding-unfolding transitions, establishing 10 T as the critical magnetic field strength for enhancing functionality in dairy and bioactive delivery applications.