Impact of varying magnetic field conditions on the microstructure and quality of yellowfin tuna during assisted re-freezing.

As traditional freezing methods can cause serious and irreversible damage to fish, in order to improve the freezing quality of yellowfin tuna, the effects of magnetic field (MF) treatments on freezing behavior and muscle quality were investigated. Six conditions were applied: no magnetic field (NMF), static magnetic fields (SMF) at 1 and 3 mT, and alternating magnetic fields (AMF) at 1, 3, and 5 mT. Compared to NMF, MF-assisted freezing significantly reduced the phase transition time and improved physicochemical properties, myofibrillar protein stability, and ice crystal morphology. Notably, SMF-1 and AMF-3 yielded the most favorable results, leading to more compact microstructures, uniform water distribution, and smaller, evenly distributed ice crystals. These conditions effectively maintained muscle integrity and reduced freezing-induced damage. Overall, MF-assisted freezing, especially under SMF-1 and AMF-3, shows potential as a novel strategy to enhance the freezing process and preserve the quality of fish products.