The document discusses Pulsed Electric Fields (PEF) technology as an innovative, non-thermal food processing method that efficiently inactivates microorganisms while preserving food quality. It outlines the fundamental mechanisms, treatment systems, and various applications of PEF, including its role in processing juices, dairy products, and enhancing drying efficiency. The document highlights the advantages of PEF over conventional thermal processing in maintaining sensory and nutritional values of food.

1. M.Venkatasami
M.Tech (Processing and Food Engineering)
Department of food process engineering
AEC&RI, TNAU

2. INTRODUCTION
HISTORICAL BACKGROUND
MECHANISMS OF ACTION
PEF TREATMENT SYSTEMS
TREATMENT CHAMBER DESIGN
PROCESSING PARAMETERS
APPLICATIONS
PEF 2

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

4. PEF 4

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,

11. PEF 11
Continuous Systems
Co-linear configurationParallel plate configuration Coaxial configuration

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