Pulsed electric field (PEF) technology uses short, high voltage electric pulses to induce pores in cell membranes, causing microbial inactivation and cell disintegration without significantly heating the food. This allows for longer shelf life and fresh quality retention compared to thermal pasteurization. PEF works by exceeding the critical transmembrane potential of cells, typically around 10 kV/cm for E. coli. It is effective against vegetative microbes and can reduce microbial loads by 4-6 logs but has limited effectiveness against spores, viruses or enzymes. PEF is suitable for liquid, semi-liquid and some solid foods but requires expensive equipment and refrigeration to extend shelf life.

1. NOVEL TECHNOLOGIES FOR
FOOD PROCESS
Applications of Pulsed Electric Fields
Technology for the Food Industry
(PEF)
Iğdır University
Food Engineering
Özen Sökmen

2. INTRODUCTION
 Pulsed electric field processing (PEF) is an efficient
non-thermal food processing technique using short,
high voltage pulses.
 PEF or Pulsed Electric Field technology is a
alternative process to pasteurisation and
sterilisation methods.

3. WHAT IS PULSED ELECTRIC FIELDS ?
 These pulses induce portion of plant, animal and
microbial cells, leading to cell disintegration and
microbial inactivation.
 Pulsed electric field processing (PEF) is an efficient
non-thermal food processing technique using short,
high voltage pulses.

4. PEF: HOW IT WORKS ?
 High intensity (PEF) processing involves the application of
pulses of high voltage (typically 20-80 kV/cm) to foods placed
between 2 electrodes.
 PEF affects Cell membrane and Loss of barrier function;
 Cell cytoplasm is surrounded by a thin semi-permeable layer,
the cell membrane. The membrane acts as a semi-permeable
barrier for the intra- and extracellular transport of ions and
macromolecules.

5.  This cell membrane is a phospholipid bilayer with a thickness
of 5 nanometer (nm). By exposing the cell to a pulsed
electrical field the cell membrane becomes punctured. The
membrane is punctured with small pores of 50-100 nanometer
each . This effect is called electroporation, which is the loss of
the cell’s barrier function allowing access to the cell’s valuable
contents.

6.  Electroporation takes places after 1 microsecond (µs). The process is
quick, flexible, energy-efficient and because heat is minimized, products
have a longer shelf life whilst maintaining better nutritional value than with
traditional food processing techniques.
 The high voltage pulses applied induce pores in cell membranes, causing
a loss of barrier function, leakage of intracellular content and loss of
vitality. The treatment is applied continuously in a chamber ‒ a setup of
multiple electrodes

9.  While being pumped (liquids and semi viscous
liquids) or transported (solids) through the
treatment chamber, the product is exposed to the
high voltage pulses. The required treatment time is
less than a second.

10. TARGET OF PEF
 Pulsed Electric Field (PEF) processing or electroporation works by
puncturing the cell membrane, whatever the size of cell. The process is
targeted, gentle and clean. As a result, we measure dramatic increases
in yield and the preservation of pigments, antioxidants and vitamins.
PEF makes healthy products last longer.
 Loss of cell membrane barrier function causes microbial death. Despite
its targeted effect on cell membranes PEF does not affect vitamins,
flavors or proteins. This allows microbial decontamination of heat
sensitive liquids whilst retaining their sensory qualities and functional
value.

11.  Membrane disruption occurs when the induced membrane
potential exceeds a critical value of 1 V in many cellular
systems, which corresponds to an external electric field of
about 10 kV/cm in the case of E. coli. In case of killing E. coli
and reducing the microbial load of a liquid you need a
minimum threshold value of about 10 kV/cm. Electroporation
is irreversible above a certain threshold.
 And more Self Life.
E.Coli with TEM

12. WHAT TYPES OF FOODS CAN BE TREATED ?
 Solid, semi-liquid and liquid foods can be treated.
 Treatment of plant or animal tissue aiming on cell disintegration has
practically no size limitations.
 It can be applied to whole fruits, vegetables and potato tubers, fruit or
vegetable pieces and fruit or vegetable mashes, prior to separation
processes. However, the maximum size of the plant or animal tissue
must be smaller than the gap of the treatment chamber.

13.  Example ; Bread
Milk
Orange Juice
Liquid eggs.
And we can see some examples
http://www.pulsemaster.us/pef-products

14. MICROBIAL INACTIVATION
 Microbial Inactivation increases with an increase in the electric field intensity
-Above the critical transmembrane potential
 Gram-positive are more resistant to PEF than Gram-negative
 Yeasts are more sensitive to electric fields than bacteria due to their large
size
 At low electric fields they seem to be more resistant than gram negative cells
Listeria innocua
with TEM

15.  Whereas all kinds of vegetative spoilage and pathogenic
microorganisms can be inactivated, a limited effect on enzymes,
spores and viruses are found.
 Other constituents such as vitamins, minerals, pigments and flavors
are also retained. In contrast to heat treatment the functionality and
nutritional value of proteins is hardly affected
 A comparison between the inactivation of 2 yeast spp. of different
size showed that the field intensity need to achieve the same
inactivation level was inversly proportional to cell size

16. PEF EFFECTS ON ENZYMES
 51,7% and 83% of pepsin was inactivated at 37,0 kV/cm and 71,8kV/cm for a
treatment time of 126 µs, respectively
 Activity of polyphonol oxidase (PPO) decreased 38,2% when treated at 34,9
kV/cm 34,2 kV/cm, respectively
 Enzyme inactivation was determined for lactoperoxidase in milk in comparison to
thermal inactivation.
 Both PEF and the induced heat contributed to the observed inactivation effect,
depending on the properties of enzymes and test conditions

17.  Graphices demonstrate to activation decrease
(Iysozyme) during the PEF processing.

18. Activation decrease (Iysozyme) during the PEF processing.

19. ADVANTAGES
 Less treatment time
 Low treatment temprature
 Increase shelf life and maintain food safety with low processing costs.
 Fresh guality, higher nutritional value (unchange color and flavor)
 PEF inactivates vegatative micro organisms including yeast, spoilage
micro organisms and pathogens.

20.  Reduction in microorganisms: 4-6 log (especially
milk)

21.  It can be uses to pasteurize fluids such as juices, milk and soups
without using additives
 It can support or replace conventional processing techniques such as
enzymatic maceration and mechanical disintegration.

22.  Low electric field strength and/ or pulse number causes reversible cell
rupture stimulating a stress reaction in plants or cell cultures and
allowing enzymes or proteins with potential health benefits to be
harvested.
 Used for pretreatment applications for improvement of metabolite
extraction

23. DISADVANTAGES
 High capital cost.
 PEF treatment is effective for the inactivation of vegetative bacteria
only.
 Micro-organisms are destroyed by PEF but spores, with their tough
protective coats, and dehydrated cells are able to survive.
 Refrigeration is required to extend shelf-life.
 Enzymes more resistant than vegetative bacteria to treatment

24.  PEF treatment has considerable added value for specific product
ranges.
 PEF is a continuous processing method, which is not suitable for solid
food products that are not pump able.
 PEF processing is restricted to food products with no air bubbles and
with low electrical conductivity.
 https://www.youtube.com/watch?v=fFa3NFUHzWE
 https://www.youtube.com/watch?v=YBhrj6W9N2M

25. REFERANCES
 http://www.intechopen.com/books/structure-and-function-of-food-
engineering/pulsed-electric-fields-for-food-processing-technology#SEC15
 http://italianfoodmaterialsandmachinery.com/pulsed-electric-fields-an-alternative-
method-to-heat-treatment-technologies/
 http://www.pulsemaster.us/pef-pulsemaster/faq
 http://www.elea-technology.eu/elea-pef
 http://www.foodsafetymagazine.com/magazine-archive1/februarymarch-
2015/novel-food-safety-technologies-emerge-in-food-production/
 https://www.safaribooksonline.com/library/view/case-studies-in/9781845695514/
 http://link.springer.com/article/10.1007%2Fs12393-009-9011-7
 http://link.springer.com/article/10.1007%2Fs11947-011-0731-3
 http://link.springer.com/chapter/10.1007/978-94-007-1100-6_1
 https://www.youtube.com/watch?v=fFa3NFUHzWE
 https://www.youtube.com/watch?v=YBhrj6W9N2M

26. Thank you
for listening and attantion