An Innovation in Magnetic Field Assisted Freezing of Perishable Fruits and Vegetables: A Review

ABSTRACT

Freezing is an important preservation technique to preserve the raw food and to extend the shelf life for longer duration of time by reducing the product temperature to −18°C or below. Effectiveness of freezing depends on size, shape, distribution of ice crystals, and freezing rates. Application of already existing traditional methods of freezing have lower freezing rates resulting in formation of large ice crystals and high drip loss upon thawing. So, as to overcome the above drawback, the concept of magnetic field assisted freezing has been introduced. In this method, magnetic field is generated around the frozen product either by using the permanent magnets or by electromagnets. In this innovative technology, the nuclear and electronic spins of water molecules are aligned in the direction of magnetic field that prevents clumping and keep them under super cooled conditions to accelerate the freezing speed resulting in formation of small ice crystals without breaking of cell membranes. Thus application of magnetic field helps to enhance the freezing rate and to improve the quality of frozen food in terms of appearance, flavour, texture, and freshness in comparison to other existing freezing methods.

KEYWORDS:

• Magnetic field
• freezing
• application
• super cooling
• conventional freezing
• food preservation