Effects of static magnetic fields on supercooling and freezing kinetics of pure water and 0.9% NaCl solutions. (January 2018)

• Record Type: Journal Article
• Authors: Otero, Laura; Rodríguez, Antonio C.; Sanz, Pedro D.
• Is Part Of: Journal of food engineering. Volume 217(2018)
• Page Start: 34
• Page End: 42
• Publication Date: 2018-01
• Subjects: Static magnetic fields -- Spatial magnetic gradients -- Supercooling -- Freezing kinetics -- Water -- Chloride sodium solutions; 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.2017.08.007
• Languages: English
• ISSNs: 0260-8774

Abstract

Abstract: Previous papers in the literature show no agreement on the effects of static magnetic fields (SMFs) on water supercooling and freezing kinetics. Hypothetical effects of the SMF orientation and the presence of ions in the sample are also unclear. To shed light on this matter, we froze 10-mL pure water samples and 0.9% NaCl solutions subjected or not to the SMFs generated by two magnets. We found that the relative position of the magnet poles affected the magnetic field orientation, strength, and the spatial magnetic gradients established throughout the sample. Thus, the SMF strength ranged from 107 to 359 mT when unlike magnet poles faced each other whereas it ranged from 0 to 241 mT when like magnet poles were next to each other. At both conditions, we did not detect any effect of the SMFs on the time at which nucleation occurred, the extent of supercooling, and the phase transition and total freezing times in both pure water and 0.9% NaCl solutions. More experiments, under well-characterized SMFs, should be performed to definitively evaluate the ability of SMFs in improving food freezing. Highlights: The relative position of the magnet poles affected the SMF orientation and strength. Significant spatial magnetic gradients were established throughout the samples. Magnetic gradients were in the 107–359 mT and 0–241 mT range in SMF-A and SMF-R samples. SMFs produced no effect on supercooling and freezing kinetics of water and 0.9% NaCl solutions. An accurate SMF characterization is needed to assess the effect of SMFs on freezing.