Pulse electric field (PEF) technology uses high voltage electric pulses to permeabilize microbial and plant cell membranes. It can be used as a non-thermal pasteurization method for foods like juices. PEF systems generate short pulses of 15-80 kV/cm for under 1 second using pulse-forming networks and fast switches. This disrupts microbial and plant cell membranes through electroporation. PEF can inactivate bacteria and yeasts while maintaining sensory and nutritional properties of foods. It has potential applications in juice, dairy, meat, and plant oil extraction processing. However, PEF is not effective against spores and requires further research toward commercialization.

1. Pulse Electric Fields For Food Processing
Technology
Department of Agricultural & Food Engineering
IIT Kharagpur
Barun Kumar Yadav
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2. Introduction
• High voltages (≤ 100 kV ) in short ( 1-10 µs )
pulses ( up to 1000 Hz ) .
• Total Treatment time < 1 s (generally).
• Product expose to electric fields via electrodes.
• Effects includes permeabilisation of membranes.
• Classes as a “non –thermal” treatment.
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3. History of PEF (Scientific publication)
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4. Scientific publication vs other technologies
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5. Publication vs uptake of HPP
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6. Principle of Technology
• PEF processing for food preservation implies applying
short electric pulses.
• Usually 1±20 µs, but with a range of 50 ns to several
milliseconds.
• With a high field strength (15±80 kV/cm ) .
• Samples placed between two electrodes in a batch or
continuous treatment chamber.
• To generate such a fast electrical discharge, pulse-
forming networks (PFN) are used.
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7. The main components of a PFN
• Power supply: A high voltage generator which supplies
electrical energy at the selected voltage .
• One or several capacitor banks, inductors or/and resistors.
• One or several switch which deliver electrical energy to the
electrodes and the food sample.
• One (or several) treatment chamber(s) with two electrodes
between which the food sample either flows or is encased.
• An oscilloscope to measure voltage across the electrodes and
display pulse shape.
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8. Working
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9. Type of pulse wave form: PEF may be applied in the form of
exponential decaying, Square , bipolar or oscillating pulses.
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10. Mechanism of Microbial inactivation
• There are mainly two type of mechanism :
Electrical Breakdown
Electroporation
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11. Electrical breakdown
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12. Electroporation
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13. • Microbial inactivation increases with an increase in the
electric field strength.
• Gram-positive are more resistant to PEF than those that
are Gram-negative.
• Yeasts are more sensitive to electric fields than bacteria
due to their larger size.
• At low electric fields they seem to be more resistant than
Gram-negative cells.
• Spores are high resistant to PEF .
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14. Input requirement
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Input
requirements
of PEF
Microbial
inactivation
15-40kV/cm
Improvement of
mass transfer in
plant/animal cell
0.7-3.0kV/cm
In apple juice
22-34kV/cm
Sludge
disintegration
10-20kv/cm

15. PEF Critical Factors
Process
- Electric field intensity
- Pulse Width
- Treatment time and temperature
- Pulse wave shapes and polarity
Microbial entity
- type, concentration, and growth stage of microorganism.
Treatment media
- pH, antimicrobials, and ionic compounds, conductivity, and medium
ionic strength.
- Food with large electrical conductivities generate smaller peak electric
fields across the treatment chamber and therefore are not feasible for
PEF treatment.
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16. Comparison between technique ( Cost VS Technique )
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17. Advantage
• Less treatment time and low treatment temperature.
• Substitute for conventional heat pasteurization.
• Increase shelf life and maintain food safety.
• Minimally processed foods of fresh quality, which have
higher nutritional value because of color and flavor
retention.
• PEF inactivates vegetative micro-organisms including
yeasts, spoilage micro-organisms and pathogens.
• Reduction in microorganisms: 4-6 log
• It can be used to pasteurize fluids such as juices, milk and
soups without using additives.
• It increase the juice and oil extraction yeald.
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18. Disadvantage
• 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.
• Treatment does not inactivate enzymes.
• 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.
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19. Aspects to be considered in PEF
• Generation of high electric field intensities.
• Design of chamber that impart uniform treatment to foods.
• Minimum increase in temperature.
• Design of electrodes that minimize the effect of
electrolysis.
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20. Application of PEF Technology
Juice processing:
• Applying PEF to cellular tissue an increase in mass
transfer coefficients due to cell membrane
permeabilisation.
• There is 10-12% increase of juice yield when applying
electroplasmolysis to apple tissue.
• Application of PEF for juice processing provides a
potential to replace or enhance conventional cell
disintegration techniques.
• The shelf life of fresh orange juices is extended by PEF
treatment from a few days to a few weeks.
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21. Sugar Processing
• In Conventional procedures for production of sugar from
beets, disintegration and destruction of cell membranes a
thermal treatment at temperatures in the range from 70 to
78°C is applied.
• The membrane de-naturation results in an acceleration of
sugar release into the extraction media, but also cell wall
components such as pectin may become soluble and can
diminish juice purity and quality.
• A PEF treatment of sugar beets could increase mass
transfer rates and could allow to reduce extraction
temperatures and better quality of sugar can be obtained.
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22. PEF treatment of microalgae, seaweed,
and other aquatic species
• Different varieties of macro- and microalgae are sources
of vitamins, pigments, proteins as well as antixodative and
bioactive substances.
• Algae extracts applying PEF treatment could provide a
potential toward a gentler downstream processing.
• There is an increasing in the yield after PEF treatment,
mainly in the case of extractability of growth hormones.
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23. Plant Oil Extraction
 Sitzmann and Munch (1988) reported an enhanced
separation of tankage emulsions when extracting protein
and fat from animal tissue.
 A similar effect can be expected after PEF treatment of
oil seeds prior to recovery.
 Yield and quality of oils has been studied and high oil
yield was developed.
 Oil recovery from olives was improved by 7.4% after a
PEF treatment at 1.3 kV/cm in comparison to the control
sample.
 In soybean oil an increase in iso-flavonoid content was
reported.
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24. Meat & Fish Treatment
• Disintegration of animal cellular tissue is used to enhance
the curing of fish or meat products.
• In case of raw ham a long-term curing and air drying is
applied. During such procedures a PEF treatment can be
applied to improve mass transfer processes and to
accelerate curing, reducing the time requirements.
• An increase in mass transfer rates, resulting in faster
water transport to the product surface and therefore
drying time can be reduced.
• This will lead to drastic saving of energy and better
utilization of production capacities during convective air
drying.
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25. References:
• Food preservation Techniques – Peter Zeuthen and Leif Bagh,
Sarensen, CRC , Woodhead Publ. Ltd.
• Maged E.A. Mohamed and Ayman H. Amer Eissa (2012). Pulsed
Electric Fields for Food Processing Technology, Structure and
Function of Food Engineering, Prof. Ayman Amer Eissa (Ed.), ISBN:
978-953-51-0695-1, Intec, DOI: 10.5772/48678.
• Pulse electric field Technology for food industries , Fundamentels and
application - Javier Raso and Volker Heinz , Springer publ Ltd.
• http://www.foodtech-international.com/papers/PulsedElectricField.htm
• http://www.fda.gov/Food/FoodScienceResearch/SafePracticesforFood
Processes/ucm101662
• http://worldfoodscience.com/cms/index.html@pid=1006021.html
• https://www.youtube.com/watch?v=6LYAPgRyU0c
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