Effect of oscillating magnetic fields on freezing of a colloidal dispersion of superparamagnetic nanoparticles. (June 2023)

• Record Type: Journal Article
• Authors: Otero, Laura; Rodríguez, Antonio C.; Morales, Irene; Costo, Rocío; Presa, Patricia de la; Sanz, Pedro D.
• Is Part Of: Journal of food engineering. Volume 347(2023)
• Publication Date: 2023-06
• Subjects: Oscillating magnetic fields -- Freezing -- Superparamagnetic nanoparticles -- Supercooling -- Freezing kinetics; Food industry and trade -- Periodicals; Food -- Analysis -- Periodicals; Aliments -- Industrie et commerce -- Périodiques; Aliments -- Analyse -- Périodiques; Aliments -- Recherche -- Périodiques; 664.005
• DOI: 10.1016/j.jfoodeng.2023.111440
• Languages: English
• ISSNs: 0260-8774

Abstract

Abstract: Several studies suggest that single-domain biogenic magnetic nanoparticles could play a major role on the effectiveness of oscillating magnetic fields (OMFs) in improving food freezing. To evaluate the potential role of superparamagnetic biogenic particles, we performed freezing experiments in a colloidal dispersion of <10-nm maghemite nanoparticles (MNPs) subjected or not to a 31.3-mT OMF at 50 Hz. Our results show that, at our experimental conditions, Néel mechanism governs the alignment of magnetic dipole moments and, therefore, no significant MNPs rotation, able to disturb the ordering of water molecules, should be expected during OMF experiments. Accordingly, no effects of the applied OMF were observed either on supercooling, ice nucleation, or on freezing kinetics even though heat removal was slightly increased during the precooling step. These results suggest that weak OMFs usually applied in commercial freezers should not produce any significant effect on superparamagnetic nanoparticles present in food that could improve the freezing process. Highlights: A colloidal dispersion of 6.1-nm MNPs was prepared and magnetically characterized. The MNPs dispersion was frozen subjected or not to a 31.3-mT OMF at 50 Hz. Néel relaxation was the dominant relaxation process. No significant MNPs rotation should be expected during OMF freezing experiments. OMF application did not affect supercooling, ice nucleation, or freezing kinetics.