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NON THERMAL PRESERVATION
TECHNIQUES
Zarqa Azam (Roll# 27)
Riaheen Shahbaz (Roll# 29)
B.Sc. (Hons.) Food Science and Technology
Semester 8th –Regular
FST-609. Food Quality Management
Institute of Food Science and Nutrition (IFSN)
University of Sargodha, Sargodha
2016. 2

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OUTLINE:
 Introduction
 Problems
 Uses
 Cost of equipments
 Objectives
 Types of non-thermal preservation techniques
 High pressure processing
 Irradiation
 Ozonation
 Ultrasound
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CONTI..
 Oscillating magnetic field
 Pulsed electric field
 Hurdle technologies
 Pulsed light processing
 Processing with E-Beam
 Sanitizer washes
 Natural antimicrobials
 Conclusion 4

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INTRODUCTION
 Method use for processing and preservation.
 Keeping the temperature of food to minimum as much as
possible.
 Method use without heat.
 Destroy pathogens.
 Keep foods safe to eat .
 Retaining the sensory attributes.
 Nutrient content similar to raw or fresh products. 5

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PROBLEMS
 Problem with the thermal processing :
 Loss of volatile compounds
 Nutrients
 Flavour
 To overcome these problems non thermal method
 came into food industries:
 To increase the production rate
 Profit.
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USES OF NON THERMAL PRESERVATION
 Used for bulk quantities of foods.
 Mainly used in the large scale production.
Cost of equipments:
 Used in the non thermal processing is high then used in
thermal processing.
 After minimizing the investment costs of non thermal
processing methods it can also be employed in small
scale industries 7

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OBJECTIVES
 Extend shelf life
 Good quality
 Safe food with better nutrition
 Meet consumer requirements
 Better financial return to industry
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TYPES
 High pressure processing
 Irradiation
 Ozonation
 Ultrasound
 Oscillating magnetic field
 Pulsed electric field
 Hurdle technologies
 Pulsed light processing
 Processing with E-Beam
 Sanitizer washes
 Natural antimicrobials 9

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HIGH PRESSURE PROCESSING
 “High Hydrostatic Pressure” or “Ultra High Pressure”
processing.
 Method of preserving and sterilizing food
 Product processed under very high pressure
 High Pressures applied at short periods of time
(20minutes)
 The high pressure used in HPP kills most micro-
organisms :
 By damaging cell components such as cell membranes
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HOW MUCH PRESSURE?
 For food processing 200-800MPa pressure is required.
For inactivating milk enzymes;
 Alkaline phosphates and protease about 1000 MPa is
needed.
 600MPa is the optimum pressure for processing
commercial food products.
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COMPONENTS
 A pressure vessel and its closure
 A pressure generation system
 A temperature control device
 A materials handling system
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PROCESS
 Food packages are loaded onto the vessel and the top is
closed
 The pressure medium usually water is pumped into the
vessel from the bottom.
 Once the desired pressure is reached, the pumping is
stopped, valves are closed, pressure can be maintained
without further need for energy input
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ADVANTAGES
 It kills vegetative bacteria and spores
 Reduced processing time.
 Freshness, flavor, nutrients, color, and taste retained
 Shelf life is increased
 Low energy consumption
 Elimination of chemical preservatives
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APPLICATIONS:
 Used in pasteurization and sterilization of fruits and fruit
products
 Tenderization of meat
 Sterilization of heat sensitive ingredients like shellfish,
flavorings, and vitamins
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OZONATION
 Powerful sanitizer similar to chlorine or common bleach
 Ozone can reduce contamination on food and increase
storage life.
 Toxic to humans at very high doses
 Should not be used to treat high fat foods.
Principle
Ozone does not act as a systemic poison to
microorganisms, but rather, destroys them by oxidation.
Consequently, it is impossible for a microorganism to
build up any resistance to oxidation
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ADVANTAGES OF OZONE
 Instantly destroys microbes
 Eliminates chemical storage
 Environmentally friendly
 Does not affect product taste
 No harmful by-products
 Can be used in air and water
 It leaves no residues in food or water.
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IRRADIATION
 Technology that improves the safety and extends the
shelf life of food by reducing or eliminating
microorganisms and insects.
 Irradiation can make food safer for the consumer
 Irradiation to a dose of between 1 kGy and 10 kGy is an
effective method of reducing the microbial load of food. 18

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ADVANTAGES
 Extend the shelf life
 Irradiation may also inactivate enzymes..
 Low dose irradiation (less than 1 kGy) is also used to
inhibit sprouting (e.g. onion, garlic, potato)
 Used for the purpose of insect disinfestations and
inactivation 20

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ULTRASOUND
 Form of energy generated by sound waves of frequencies
that are too high to be detected by human ear, i.e.16KHz
 Ultrasound can be propagate in liquid,gasses,solids.
 Effective for inactivation of microorganisms and
enzymes.
 Produce intracellular cavitations due to micro
mechanical shocks
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ULTRASOUND IN INDUSTRY
 Major significant to industry and consumer
 Better quality and healthy food
 High efficiency
 Saves energy and cost
 Minimizing of flavor loss
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OSCILLATING MAGNETIC FIELD
 A magnetic field is defined as the region in which
magnetic material is able to magnetize the surrounding
particles.
 Magnetic field may be static or oscillating
 In order to inactivate microorganisms, flux density of 5
to 50 tesla (T) is required, corresponding to very high
intensity magnetic fields.
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CONT..
HOW HIGH INTENSITY MAGNETIC FIELDS
ARE GENERATED?
 Generated by an electric current passing through a coil
 Capacitor is charged by high voltage DC power supply
 By closing the switch
 An oscillating current is produced inside the capacitor
 And then an oscillating magnetic field is induced to the
food placed inside the magnet coil
 For high magnetic fields, superconductor coils are used
 40KA current is required
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CONTI..
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CONTI..
HOW THIS MECHANISM INACTIVATES M/O
 Magnetic fields alter the growth and reproduction of
microorganisms by both genetic and bio chemical
phenomena
 Effect may be due to magnetic field or induced electric
field
 Depending upon both features of magnetic field and
properties of food and microbial:
 The growth of microbial may be inhibited
 Or unaltered by this technique
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CONTI..
APPLICATIONS
 Some packed liquid foods such as milk, yoghurt, orange
juices etc
 They may be subjected to oscillating magnetic field with a
frequency between 5 and 550 kHz.
 For a total exposure time between 25µs and 10ms.
 Performed at atmospheric pressure and room temperature,
resulting in a temperature increase not higher than 5˚C
 Therefore a good retention of nutritional and sensory
properties of foods is assured. 27

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PULSED ELECTRIC FIELD (PEF)
 Another non-thermal technology that can be use to
inactivate bacterial cells at ambient temperatures
 More suitable for liquids and semi liquid foods which
can be easily pumped
 Can be used to increase the shelf life of soups, milk,
whole liquid eggs and fruit juices 28

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CONTI..
HOW THIS PROCESS OCCURS?
 Process involves placing the food material between two
electrodes
 And passing pulses of high electric field strength (1-50
kV/cm)
 Since the pulses are applied for short durations (2µs to
1ms) the negative impact on food quality due to heat
processing is highly diminished
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CONTI..
APPLICATION OF PEF RESULTS IN:
 Cellular death due to generation of pores
(electroporation) in the bacterial cell membrane
 Without having an effect on enzymes or proteins present
in foods
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CONTI..
EFFECTIVENESS
 The effectiveness of this technique will strongly depend
upon
 Treatment time
 Electric field strength
 Specific energy of the pulses
 Although this technique is useful, inactivation has only
been achieved in the range of 3-4 logs.
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CONTI..
ADVANTAGES AND LIMITATIONS
 Advantages:
 Pulse applied for shirt period so no generation of heat
 Less usage of energy
 Limitations:
 Cannot be applied to the foods which cannot
withstand high fields
 And foods that form bubbles
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HURDLE TECHNOLOGY OR SYNERGISM
 Hurdle approach or process of using multiple
technologies is an effective approach to microbial
decontamination in comparison to that of a single
technology alone
 Deliberate and intelligent combination of preservative
treatment can help in maintaining the quality of food and
delivering almost similar level of microbial destruction
 At the same time it warranties to counteract the negative
effect of individual technologies on food quality 33

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CONTI..
 The choice of hurdles will strongly depends on
 The type of food it is being applied to in addition to
the mode of inactivation
 For example:
 Exposure of egg shells contaminated with
S.Enteritidis with UV radiation (1500-2500 µW/cm²)
followed by ozone (5 lb/in² gauge for 1min) resulted
in an inactivation of 4.6 logs or more in a total
treatment time of 2 min
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PULSED LIGHT (PL) PROCESSING
 Non thermal technology that uses short, intense pulses of
white light which include ultraviolet, infrared, visible
light
 Treatment of foods by PL has been approved by FDA (21
CFRI79.41)
 PL is like a camera flash but far more intense 35

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CONTI..
HOW IT WORKS?
 When this light is flashed on foods, it kills
microorganisms but has minimal impact on foods
 Short flashes of this intense light are used to prevent the
temperature of the food from increasing
 Within PL there is ultraviolet light that kills the
pathogens by disrupting their DNA. 36

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PROCESSING WITH E-BEAM
 Non-thermal technology where the high energy electrons
(close to the speed of light) are aimed at solid or liquid
foods
 Reducing the number of or eliminating pathogens, pests
or insects
 Unlike Gamma radiations this technology uses no
radioactive isotopes
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CONTI..
HOW IT WORKS?
 E-beam may work against pathogens such as viruses and
bacteria
 by breaking the linkages in RNA or DNA
 and by disrupting other parts that are essential to
organisms
 Some Drawbacks include:
 Limited penetration depth through food
 High initial cost 38

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NATURAL ANTIMICROBIALS
 Since ancient times spices and herbs have been used for
preventing food spoilage and deterioration
 Also for extending shelf life and food quality
 The antimicrobial effect of these components is a result
of an increase in permeability of the cytoplasmic
membrane which leads to the loss of cellular constituents 39

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CONTI..
EXTRACTS FROM VEGETABLES, HERBS
 Plants secondary metabolites such as essential oils and
natural plant extracts have also been reported to have
antimicrobial, antifungal and anti-insecticidal properties
 Extracts from capsicum, seaweeds and green tea have
been found to inhibit the growth of Salmonella spp.
 Tomatoes treated with 100ppm oregano (herb) results in
2.78 log reduction.
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USING SANITIZER WASHES
 Sanitizers like chlorine, are used by the food industry
that helps to kill pathogens in food and on
equipments/utensil surfaces
 FDA regulates the sanitizers to be used by food industry
 Microorganisms attach to the food, can lower the
effectiveness of sanitizer and to address this problem
 Use of surfactants (components of detergents) is being
studied to enhance the effectiveness of sanitizer 41

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CONTI..
HOW IT WORKS
 Combining food grade surfactants with sanitizers
 Improves the killing effectiveness
 When applied to surface of food
 By “Loosing” microorganisms attachment
 Allowing the sanitizer to be more potent antimicrobial
agent
 The combination of sanitizer and surfactants has
not yet been commercialized but shows greater
potential.
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HENCE:
 Non Thermal or Alternative Food Processing
Methods Enhance the
 MICROBIAL SAFETY
 FOOD QUALITY
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