1.
SEMINAR
“PULSED ELECTRIC FIELD”
PRESENTED BY MS:ANSARI SANA

2.
WHY PROCESS FOODS?
1. Extend shelf life
2. Maintain sensory properties
3. Maintain nutritive properties
4. Ensure safety
5. Make more convenient.
6. Economic value
FOOD PROCESSING
THERMAL PROCESSING NONTHERMAL PROCESSING

3.
WHAT IS PULSED ELECTRIC FIELD?
 Pulsed electric fields is a non thermal method of food preservation
that uses short pulse of electricity for microbial inactivation .
 It is also called High Electric Field Pulses (HELP).
 It uses short electric field pulses to preserve food.
 It works in intensity of 10-80 kV/cm with duration of micro to
milli seconds.
 (Pulse - A pulse is a single disturbance that moves through a
medium from one point to the next point)

4.
HISTORY
 In 1920’s a process called ‘electropure’ was introduced in europe
and the USA. In milk pasteurization it is used by passing current
within carbon electrode treatment chamber.
 In 1950’s pulse discharges of high voltage electricity across two
electrodes for microbial inactivation is first investigated.
 In 1967- first non thermal lethal effect of homogeneous pef on
microbes by sale and hamilton
 Early patents by krupp in germany for inactivation of vegetative
microorganisms in milk and fruit juices with an electric field
strength up to 30 kv/cm.
 1987 - pure pulse technologies, usa use electric fields and their
effect on fruit juice quality was investigated by dunn and pearlman.

5.
PRINCIPLE
 Basic principle - keeping food below temperatures normally used in
thermal processing.
 PEF technology is the application of short pulses of high electric
fields with duration of microseconds micro- to milliseconds and
intensity in the order of 10-80 kV/cm.
 The processing time is calculated by multiplying the number of
pulses times with effective pulse duration.
 The process is based on pulsed electrical currents delivered to a
product placed between a set of electrodes.
 The applied high voltage results in an electric field that causes
microbial inactivation.

6.
COMPONENTS
 Pulse generator
 Treatment chamber
 Monitoring and controlling devices

7.
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

8.
APPLICATION OF PEF
 Pasteurization of food such as juices, milk, yogurt,
soups and liquid eggs.
 Color change in fruit juices (prolonged storage)
less in juices treated by PEF.
 Reducing solid volume (sludge) of wastewater
 Apple juice, orange juice, milk, liquid egg and
brine solution

9.
ADVANTAGES
 Less treatment time.
 Low treatment temprature.
 It can operate at room temperature to retain quality and heat-
sensitive vitamins.
 Increase shelf life & maintain food safety with low processing costs.
 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.

10.
 It can be used to pasteurize fluids such as juices, milk and soups
without using additives.
 PEF causes the formation of large, permanent pores in cellular
tissues, which can be used to improve juice yield etc
 PEF can be used as continuous process.
 Used for pretreatment applications for improvement of metabolite
extraction.

11.
DISADVANTAGES
 High capital cost.
 PEF treatment is effective for the inactivation of vegetative bacteria
only.
 PEF is a non-thermal process, there is an increase in temperature
occurs in treatment chamber.
 Refrigeration is required to extend shelf-life.
 Treatment does not inactivate enzymes
 Not useful for solid foods.
 The method of inactivation is still theoretical and not clearly
studied.
 Availability of commercial units is less.
 Still under research and development.

12.
APPLICATIONS
Microbial Inactivation by PEF
 Application of pulsed electric fields technology has been
successfully demonstrated for the pasteurization of foods such as
juices, milk, yogurt, soups, and liquid eggs.
 PEF technology has recently been used in alternative applications
including drying enhancement, enzyme activity modification,
preservation of liquid and semisolid food products, and waste water
treatment, besides pretreatment applications for improvement of
metabolite extraction.

13.
JUICE PROCESSING
 When PEF treatment is introduced, juice of exceptional sensorial quality
is obtained that closely resembles the juice of freshly squeezed fruits but
which is safe from a microbial point of view.
 An additional advantage for producers is the extension of the shelf life
that is obtained.
 The shelf life of fresh orange juices is extended by PEF treatment from a
few days to a few weeks.
 This extension considerably simplifies the distribution of this kind of
juice and results in less waste of juice that otherwise would have expired

14.
 PEF technology has recently been used in drying enhancement,
enzyme activity modification, preservation of liquid and semisolid
food products, and waste water treatment, besides.

15.
it is better than thermal processing but this technique is only for
liquids not for solids that’s why it is not uses commercially.

16.
REFERENCES
 Ade-Omowaye, B. I. 0., Eshtiaghi, N., and Knorr, D., (2000),
Impact of high intensity electric field pulses on cell permeabilisation
and as pre-processing step in coconut processing, lnnov. Food Sci.
Emerg. Techno!. 1(3): 203-209.
 Ade-Omowaye, B. I. 0., Taiwo, K, and Knorr, D., (2002), Use of
pulsed electric field pretreatment to improve dehydration
characteristics of plant based foods, Trends Food Sci. Technol. 12:
285-295.
 Alvarez, 1., Pagan, R., Condon, S., and Raso, J., 2003b, The
influence of process parameters for the inactivation of Listeria
monocytogenes by pulsed electric fields, Int. J. Food Microbiol. 87:
87-95.