What is it about?

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.

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Why is it important?

Although it has been more than 10 years since magnetic freezers were introduced in the market, evidence of the efficacy of magnetic fields in improving the quality of frozen products has not yet been found. Data in the literature are frequently confusing and apparently contradictory and, therefore, much more research is needed to confirm the potential benefits of MFs on freezing. After examining the magnetic properties of water, the low strength of the MFs applied in ABI freezers (usually lower than 1 mT) casts doubt on the effects that these extremely weak MFs can have on water crystallization, but other mechanisms could be affected. Many doubts also arise concerning the working principles of Proton freezers. Although the scientific community has frequently questioned the science behind magnetic freezers, it sounds strange that manufacturers have not yet presented conclusive evidence to dissipate any doubt as far as their efficacy is concerned. In any case, investigations on magnetic freezing should cover not only MF strengths and frequencies currently used in commercial freezers but also much more wide ranges to have a complete view of the potential effects of magnetic fields on freezing of biological products. Only after finding positive results, mechanisms involved in such results should be investigated. Although patents on magnetic freezing claim that magnetic fields mainly affect water supercooling, the role of other molecules and different mechanisms should not be neglected.

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This page is a summary of: Effects of Magnetic Fields on Freezing: Application to Biological Products, Comprehensive Reviews in Food Science and Food Safety, March 2016, Wiley,
DOI: 10.1111/1541-4337.12202.
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