Effect of oscillating magnetic field (OMF) on the supercooling behavior of iron-oxide nanoparticle (IONP) agar model system

Freezing extends the shelf life of foods but often leads to structural damage due to ice crystal formation, negatively impacting quality attributes. Oscillating magnetic field (OMF)-assisted supercooling has emerged as a potential technique to overcome these limitations by inhibiting ice nucleation and maintaining foods in a supercooled state. Despite its potential, the effectiveness and underlying mechanisms of OMF-assisted supercooling remain subjects of debate. In this study, the effects of OMF on the supercooling behavior of an agar-based food model system containing iron(III)-oxide nanoparticles (IONP) were investigated. Agar samples containing IONPs at various concentrations (3, 6, 12 and 15 mg per 100 mL) were prepared to simulate the presence of ferric materials responsive to OMF. The samples were exposed to an external OMF (10 mT, 10 Hz) at -8°C for 24 h. Higher supercooling probabilities were achieved in the IONP-containing samples, with probabilities of 75%, 75%, and 90% for the 3 mg, 6 mg, and 12 mg concentrations, respectively. In contrast, lower supercooling probabilities of 60% and 55% were exhibited by the control samples (without nanoparticles) and samples containing zinc nanoparticles (ZNPs), respectively. It is suggested that the enhanced supercooling stability in IONP samples is due to the interaction between the magnetic nanoparticles and the OMF, inhibiting ice nucleation possibly through the magneto-mechanical motion affecting water molecule orientation and hydrogen bonding networks.