Emerging pulsed electric field (PEF) and static magnetic field (SMF) combination technology for food freezing

The potential of an innovative freezing technique by applying combined pulsed electric field (PEF) and static magnetic field (SMF) was successfully tested and validated. 0.9% sodium chloride (NaCl) solution was frozen under the PEF (1.78 V cm^-1, duty ratio: 0.5) at the frequencies of 0-20 kHz and different SMF conditions (attractive and repulsive). At -20 °C, an increase in the working frequencies reduced the phase transition time and the shortest phase transition time (1443 ± 2 s) was obtained at 20 kHz. The patterns of ice crystals became uniformly round (roundness: 0.88-0.90) under the PEF. The effects of attractive and repulsive SMFs showed different patterns in ice crystal formation with the shortest phase transition time under the repulsive SMF. The combined PEF (1.78 V cm^-1 at 20 kHz) and repulsive SMF resulted in an effective and synergistic freezing process, forming uniformly round and the smallest mean size of ice crystals in the shortest phase transition (1004 ± 3 s).