Pulsed electric field (PEF) processing is an emerging non-thermal food preservation technology. PEF technology is established on the utilization of electric fields to remove food-borne pathogens and to subjugate the spoilage microorganisms in foods. This technology is notably acknowledged for its capability to amplify the mean life of food products without the utilization of heat also preserving the quality aspects such as sensory and nutritional attributes, together with enabling the safety of food products
3. Highly appreciated as a non-thermal processes
The most appealing technologies due to its short treatment times and reduced
heating effects
Enables inactivation of vegetative cells of bacteria and yeasts in various foods
Inactivates microorganisms at lower temperatures and preserves the sensory and
nutritional value of foods
An alternative substitute for conventional thermal processing of liquid food
products such as fruit juices, milk, and liquid egg
PEF 3
5. Electrical breakdown of
cellular membranes
Phospholipid
vesicles
Planar
bilayers
Microorganisms
Model
systems
Permeabilization of a cell
membrane
Formation of a
pore
Stability of
the pore
Two key
steps
Primary effect of PEF on biological cells
• Local structural changes
• Breakdown of the cell membrane
PEF 5
6. Two Theories
Formation of a
transmembrane
potential
1
Electromechanical
instability theory
2
Schematic depiction of mechanism
of membrane permeabilization by
electrocompressive forces induced
by an external electrical field
PEF 6
7. PEF 7
Irreversible
breakdown
of the cell
membrane
Increased
electric field
strength
Increased
pulse width
Increased
number of
pulses
Osmotic imbalances and cell swelling was related to membrane rupture after
opening of pores
• Initial perforation of the cell membrane
• Time-dependent pore expansion
Two-step mechanism
8. PEF 8
Main components
• An impulse generation system/ PFN
• A treatment chamber
Pulse-forming network (PFN) Treatment chamber
Power supplies (voltages up to 60 kv) Batch System
Switches (Ignitron, Thyratron , Tetrode, Spark
Gap, Semiconductors)
Continuous Systems
Capacitors (0.1-10 µf)
Inductors (30 µh)
Resistors (2 Ω-10 MΩ)
Parallel plate configuration
Coaxial configuration
Co-linear configuration
9. PEF 9
Block diagram of
pulse power system
Pulse generator with
single-pulse energy-
storage tank and ON-
switch
10. PEF 10
Employed to transfer high voltage pulse to food
Consists of two electrodes separated by insulating material
One connected to the high voltage source
Another connected to the ground
Floating electrodes (i.e. both connected to the pulse generator)
Continuous Systems > Batch System
Co-field arrangements are advantageous
Treatment chamber,
12. PEF 12
Electric field strength
Treatment time, specific energy and pulse geometry
Treatment temperature
Treatment medium factors
Conductivity
Effect of air bubbles and particles
Cell characteristics
Main processing parameters
13. PEF 13
Pasteurization of various food products
Juices
Milk & dairy products
Soup
Liquid eggs
Enhancement of drying efficiency
Modification of enzymatic activity
Solid food preservation
Waste water treatment and extraction
14. PEF 14
•Sun, D-W. 2014. Emerging technologies for food processing: Elsevier.1
• Raso-Pueyo, J, and V Heinz. 2010. Pulsed electric fields technology for the
food industry: fundamentals and applications: Springer Science & Business
Media.
2
• Lelieveld, HL, S Notermans, and S De Haan. 2007. Food preservation by
pulsed electric fields: from research to application: Elsevier.3