Tag: notes on non thermal processing techniques

Jul 23

Non Thermal Preservation of Food – Oscillating Magnetic Field (OMF)

Oscillating magnetic field (OMF) is generated with electromagnet of alternating current. The intensity varies periodically according to frequency and type of wave in the magnet. OMF is applied in the form of constant amplitude or decaying amplitude sinusoidal wave. The magnetic field may be homogenous or heterogeneous. In homogenous field, field intensity (B) is uniform in the area enclosed by the magnetic field coil. In heterogeneous field, field intensity (B) is non – uniform with the intensities decreasing as distances from the center of the coil increases. Read more

Jul 20

Non Thermal Preservation of Food – Ohmic Heating

Food can be heated by either direct or indirect methods.
Direct heating: In this method of heating, heat is generated within the product. Example; Dielectric heating, Ohmic heating, Pulse Electric Field (PEF), High Pressure Technology (HPT).
Indirect heating: This method of heating relies on heat that is generated externally being applied to the surface of food mostly by radiation, convection and conduction. Example; Infrared heating.
Non thermal preservation of food includes food preservation by following methods.
1. Ohmic heating
2. Dielectric heating
3. Pulse electric field (PEF)
4. High pressure treatment (HPT)
5. Oscillating magnetic field (OMF)
Ohmic heating:
operates by direct passage of electric current through food product with heat generated as a result of electric resistance. In conventional heating, heat travels from heated surface to product by conduction and convection paths. Ohmic heating is also called “resistance heating” or “electro heating”. Here alternating electric current is passed through a food and electrical resistance of the food causes the power to be translated directly into heat. As the food is an electrical component of heater, it is essential that its electrical properties (resistance) are matched to the capacity of heater. Read more