This document discusses a technique for preserving food using low-frequency magnetic fields. The technique takes advantage of the fact that magnetic fields disrupt ion transport across bacterial cell membranes, interfering with their ability to regulate pH and perform cellular reactions. The document reports on an experiment exposing Escherichia coli bacteria to low-frequency magnetic fields, which negatively impacted their growth, ability to form colonies, and oxidoreductive activity. Unlike other preservation methods, low wattage is required to kill bacteria using low-frequency magnetic fields.

1. Preservation of Food by Low-Frequency Magnetic Fields
Rudra Narayan Sarangi, Sneha Nigam & Muthukumaran.C
Department of Biotechnology, SRM University,Chennai
Inroduction
Keeping in view, the role of microbes in food
spoilage or food poisoning, we have developed
a technique creating a low frequency magnetic
field around the food to reduce the ability of
bacteria to form colonies and to decrease
oxidoreductive activity. On the basis, if
bacteria, for example, are placed in an
environment where large magnetic fields exist,
the potential across their cellular membranes
will be affected. The presence of a low
frequency magnetic field is a good example of
such an environment. This potential will
overwhelm any existing magnetic polarity in
these very small cells, and they will no longer
have control over the movement of ions across
their membranes.
Why Bacteria Hate Magnets?
The concentration of potassium (K+
) ions is
higher inside the cell than outside, and that the
opposite is true of sodium (Na+
) and chloride
(C1-
) ions. The separation of ions across the
bacterial cell wall is essential, and is
maintained by the impermeable phospholipidid
membrane. If all of the charges (+ and -) on the
inside and the outside of the cell are summed
there is a net negative charge on the
membrane's intracellular surface. In other
words, the inside of the cell is more negative
than the outside of the cell
Ion Channels and the regulation of
cellular pH
Different channel proteins transport different
ions across biological membranes. One such
ion is the proton, or positively charged
hydrogen atom [H+). The flow of protons
through ion channels in bacterial cell
membranes is used to control the pH of the
intracellular solution. The regulation of cellular
pH is crucial for the survival of biological
cells.
Inability to control pH kills
This is true because if the pH is too high or too
low, the structural integrity of intracellular
proteins is compromised. This in turn makes
the protein incapable of performing its normal
duties, most of which involve catalyzing
cellular reactions that are needed to keep the
cell alive. Bacterial cells become very 'sick'
when they lose the ability to regulate the ionic
currents through protein channels. One of the
deadliest scenarios is when the flow of protons
is disturbed. In this case, the destruction of the
protons electrochemical gradient equals the
destruction of the ability to expel them from the
cell.
Effect of low frequency magnetic Fields
The effects of low-frequency magnetic fields
(Bm=2.7–10 mT, f=50 Hz, time of exposure
t=0–12 min) on the viability and
oxidoreductive activity of gram-negative
bacteria Escherichia coli were investigated.
The growth of these bacteria was negatively
affected by such fields. Two experimental
systems—solenoid and a cylindrical spool to
find differences between non homogeneous and
“more homogeneous” magnetic fields were
compared . It is observed that there is an
analogous effects in both experimental
conditions. The growth curve of the exposed
bacteria was lower than the control one. The
ability of bacteria to form colonies decreased
with increasing magnetic field intensity and
with increasing time of exposure. The decrease
in oxidoreductive activity with increasing time
of exposure was observed, but the effect was
due to a lower amount of bacteria surviving the
exposure to the magnetic fields.
Conclusion
Unlike PEF (Pulsed Electric Field) we don’t
need 20000 V/cm2
of electricity to kill such
bacteria, a low frequency magnetic field to do
the similar work in small amount of electricity
supply by increasing or decreasing the number
of turns of wire wrapped over a metallic core
The ability of bacteria to form colonies
decreased with increasing magnetic field
intensity and with increasing time of exposure.
The decrease in oxidoreductive activity and
inability to form colonies were compared with
the assumption that the effect of magnetic field
is probably bactericidal.