Magnetic freezing is nowadays established as a commercial reality mainly oriented towards the food market. According to advertisements, magnetic freezing is able to generate tiny ice crystals throughout the frozen product, prevent cell destruction, and preserve the quality of fresh food intact after thawing. If all these advantages were true, magnetic freezing would represent a significant advance in freezing technology, not only for food preservation, but also for cryopreservation of biological specimens such as cells, tissues, and organs. Magnetic fields (MFs) are supposed to act directly on water by orientating, vibrating, and/or spinning molecules to prevent them from clustering and, thus, to promote supercooling. However, many doubts exist about the real effects of MFs on freezing and the science behind the potential mechanisms involved. To provide a basis for extending the understanding of magnetic freezing, this paper presents a critical review of the materials published in the literature up to now, including both patents and experimental results. After examining the information available, it was not possible to discern whether MFs have an appreciable effect on supercooling, freezing kinetics, ice crystals, quality, and/or viability of the frozen products. Experiments described in the literature frequently fail to identify and/or control all the factors that can play a role in magnetic freezing. Moreover, many of the comparisons between magnetic and conventional freezing are not correctly designed to draw valid conclusions, and wide ranges of MF intensities and frequencies are unexplored. Therefore, more rigorous experimentation and further evidence are needed to confirm or reject the efficacy of MFs in improving the quality of frozen products.

/pdf/effects-of-magnetic-fields-on-freezing-application-to-3hivtckagq.pdf

Effects of Magnetic Fields on Freezing: Application to Biological Products.

Freezing process assisted by electromagnetic field is one of the emerging novel food freezing technologies. The present study investigated the effects of extremely low frequency electromagnetic field (ELF-EMF) on the freezing process of two aqueous solutions with different solutes of 9 g/L sodium chloride (physiological saline) and 10 mmol/L PDADMAC (poly dimethyl diallyl ammonium chloride). Freezing parameters such as supercooling degree were determined in different frequency bands, and some parameters of thawed samples were also measured. Results showed that the supercooling degree of physiological saline was decreased and that of PDADMAC solution increased first and then decreased, while the images of ice crystals showed more and deeper cracks created in some treated samples. The surface tension and contact angle indicated that the energy balance of samples was disturbed under ELF-EMF, and the infrared and Raman spectra of the treated PDADMAC solution showed that the polarized feature and dipole moments of macromolecular groups were enhanced, which might contribute to the change of the freezing process.

Effects of extremely low frequency electromagnetic field on the freezing processes of two liquid systems

Review of hydrogen storage in AB3 alloys targeting stationary fuel cell applications

Ice nucleation is a stochastic process and it is very difficult to be controlled. Freezing technologies and more specifically crystallisation assisted by magnetic, electric and electromagnetic fields have the capability to interact with nucleation. Static magnetic field (SMF) may affect matter crystallisation; however, this is still under debate in the literature. Static electric field (SEF) has a significant effect on crystallisation; this has been evidenced experimentally and confirmed by the theory. Oscillating magnetic field induces an oscillating electric field and is also expected to interact with water crystallisation. Oscillating electromagnetic fields interact with water, perturb and even disrupt hydrogen bonds, which in turn are thought to increase the degree of supercooling and to generate numerous fine ice crystals. Based on the literature, it seems that the frequency has an influence on the above-mentioned phenomena. This review article summarizes the fundamentals of freezing under magnetic, electric and electromagnetic fields, as well as their applicability and potentials within the food industry.

https://www.mdpi.com/2073-4352/7/10/299/pdf/1

An Overview on Magnetic Field and Electric Field Interactions with Ice Crystallisation; Application in the Case of Frozen Food

Cooperative effects of Sm and Mg on electrochemical performance of La–Mg–Ni-based alloys with A2B7- and A5B19-type super-stacking structure

The supercooling and crystallization of water are affected by many factors,the investigation of which is of great significance in the field of food frozen and conservation and low temperature preservation of biology.Experiments were carried out to investigate the supercooling and crystallization of water under DC magnetic fields with different intensity.The results show that the DC magnetic field can reduce the lowest unfrozen temperature and increase supercooling.The time that water remains supercooled increases with the increase of intensity of DC magnetic filed.The crystallization speed also increases obviously.This effect is considered to relate to the formation of water molecular hydrogen bonds.

Supercooling and crystallization of water under DC magnetic fields

Study on the structure and hydrogen storage characteristics of as-cast La0.7Mg0.3Ni3.2Co0.35−XCuX alloys

Based on available formulas for cold exergy and exergy loss,exergy analysis was performed for a laboratory-scale vacuum evaporation system to produce ice slurry.By using EES software,calculations were carried out for the mixing of cold water and icy water in the system,spray and evaporation in the vacuum chamber,vapor condensation in the water trap,and saline coolant production with a chiller.The exergy losses and exergy efficiencies were obtained for the three of them and the whole system.The results show that the spray and evaporation in the vacuum chamber has the highest exergy efficiency and the vapor condensation in the water trap has lower efficiency.The lowest exergy efficiency and largest exergy losses occur in the saline production with a chiller,resulting in lower efficiency of the whole system.In order to improve the exergy efficiency of the system,the saline coolant production with a chiller should be optimized or to be replaced by other means.

Han Jitian

Papers

Supercooling and crystallization of water under DC magnetic fields

Study on the structure and hydrogen storage characteristics of as-cast La0.7Mg0.3Ni3.2Co0.35−XCuX alloys

Exergy analysis on ice slurry production system by water spray evaporation in vacuum environment