oscillating magnetic field report

1. OSCILLATING MAGNETIC FIELD
IN FOOD PRESERVATION
Made by : Kavi Dihuliya
Submitted to Er. Jinku Bora

2. It is a non thermal processing method.
Oscillating magnetic field is applied for the preservation of the
food.
Preservation of foods with OMF involves sealing food in a
plastic bag and subjecting it to 1 - 100 pulses.

3. • It effects the microorganisms cell membranes as well as malignant cells.
• 1 to 100 pulses with frequency 5 to 500 kHz at temperatures 0 to 50 degree
celsius for time 25 to 100 ms.
• Oscillating magnetic field of intensity 5 to 50 Tesla, frequency 5 to 500 kHz is
applied and it reduces microorganisms by at least 2 log cycles.
• Frequencies higher than 500 kHz tends to heat the food material. And are less
effective.
• Generally the temp of the food increases 2 - 5 degrees celsius.
• ELECTRICAL RESISTIVITY of a food needs to be greater than 10 - 25 ohms-
cm to allow OMF microbial inactivation.

4. OMF GENERATION
• MAGNETIC FIELDS ARE GENERATED BY SUPPLYING CURRENT TO
ELECTRICAL COILS.
• OMF of intensity 5 - 50 Tesla can be generated using
1. SUPERCONDUCTING COILS
2.COILS WHICH PRODUCE DC FIEDLS
3.COILS ENERGZIED BY THE DISCHARGE OF ENERGY STORED IN
CAPACITOR.

6. Effects Of Magnetic Fields On Microorganisms
• Yoshimura (1989) classified the effects of magnetic field on microbial growth
and reproduction as -
i) inhibitory
ii)Stimulatory &
iii)None observable
•Hoffman (1985) reported inactivation of microorganisms with OMF in Milk,Yogurt,
Orange juice and bread roll.
•One pulse of OMF was adquate to reduce the bacterial population between 10^2
and 10^3 cfu/g.
• Acc. to Hofmann Oscillating magnetic field of intensity 5 to 50 Tesla, frequency 5
to 500 kHz was applied and it reduced microorganisms by at least 2 log cycles.

8. EXPOSING Yeast cells to 5T sedimentation pattern was affected but not gene
expression but exposing yeast cells to 14 T Static magnetic field observed a
slight change in gene expression
When an oscillating magnetic field strength of 12.0 T was applied to milk at a frequency
of 6000 Hz, cells were reduced from 25,000 to 970ml−1

9. MECHANISMS OF MICROBIAL INACTIVATION
• OMF could loosen the bonds between ions and proteins.
• Applied electromagnetic signals transfer energy to ions and thus indirectly
affect the metabolic activities in which they are involved.
• breakdown of covalent bonds in the DNA molecules and inhibition of the
growth of micro-organisms.
• Damage to Calcium and Magnesium ions.
• High Intensity Magnetic field affects membrane fluidity.