Food irradiation uses ionizing radiation like gamma rays, x-rays, or electron beams to kill microorganisms and insects in food to reduce spoilage and prevent foodborne illness. It can disinfest, inhibit sprouting, extend shelf life, and improve food quality and safety. Irradiation is a cold process that doesn't significantly raise food temperatures. It is used for fruits, vegetables, spices, meat, seafood, and more. Common applications include disinfestation, sprout inhibition, pathogen reduction, and extending shelf life.

1. Food Irradiation

2. the level of food loss is high (more
than 40% for fruits & vegetables
and higher for fish & meat)
According to the United Nations,
more than 30 percent of the mortality
rate world-wide is caused by
alimentary diseases
Some agricultural products are
important commodities in
international trade. (infestation of
several species of insects and mites)
The presence of parasites, some
microorganisms, yeast and moulds
are also the source of problems,
(toxin formation)

3. Newer Method:
Irradiation
Oldest
Methods
Drying
Fermenti
ng
Salting
Smokin
g
Newer
Methods
freezing
Cannin
g
Refrigerat
ion
Preservati
ves
Pesticid
es
applied to fresh,
frozen or cooked
products.
physical safe
environmental
ly clean
efficient
technology

4. • Physical treatment that consists of exposing foods
either prepackaged or in bulk to the direct action of
electronic, electromagnetic rays
• When made to bombard against materials, they
can knock off an electron from an atom or
molecule causing ionization.
• For this reason, these are often called ionizing
irradiation.
• The X- and gamma-rays are very short
wavelength radiations that have very high
associated energy levels.

6. • Gamma Rays
come from the spontaneous disintegration of
radionuclides.
 cobalt-60 (1.17 and 1.33 MeV) : produced from cobalt-
59
 caesium- 137 (0.662 MeV) : a spent fuel from nuclear
reactors
 Nuclear Waste
 Good penetration
• Electron Beams
Stream of high-energy electrons propelled from an
electron gun (maximum energy 10 MeV).
Similar to Beta Particles
No Waste, In-line equipment
• X-rays
▫ beam of accelerated electrons is directed at a thin plate
of gold (or other metal), producing a stream of X-rays
exiting from the other side (5 Mev)

8. Accelerated electrons:
• The electron beam is a stream of high energy
electrons, propelled out of an electron gun.
• This electron gun apparatus is a larger version of a
standard television tube.
• The electron beam generator can be simply switched
on or off.
• There are no radioactive materials in the process.
The electrons can penetrate food only to a depth of
three centimeters, or a little over an inch, so the
food to be treated must be no thicker than that to be
treated all the way through.
• Two opposing beams can treat food that is twice as
thick. E-beam medical sterilizers have been in use
for at least fifteen years.

10. • Gamma rays and X-rays
▫ form part of the electromagnetic spectrum, like
radio waves, microwaves, ultraviolet and visible
light rays.
▫ Gamma rays and X-rays are in the short wave
length, high-energy region of the spectrum.
▫ Both Gamma and X-rays can penetrate foods to a
depth of several feet.

11. Gamma Rays
• Cobalt-60 the choice for gamma radiation source
• produced by neutron bombardment in a nuclear reactor
of the metal cobalt-59, then doubly encapsulated in
stainless steel pencils to prevent any leakage during its
use in an irradiator.
• Cobalt-60 has a half-life of 5.3 years,
• highly penetrating and can be used to treat full boxes of
fresh or frozen food.
• over 80% of the cobalt-60 available in the world market
is produced in Canada.
• Other producers are the Russian, Republic of China,
India and South Africa.
• Cesium 137 is the only other gamma-emitting
radionuclide suitable for industrial processing of
materials.
• It can be obtained by reprocessing spent, or used,
nuclear fuel elements and has a half-life of 30 years.

12. X-Ray Facility
• Food can also be irradiated by X-rays. In this system an electron
beam accelerator targets electrons on a metal plate.
• Some energy is absorbed and the rest is converted to X-rays.
• Like gamma rays, X-rays can penetrate food boxes up to 15 inches
thick or more, thus permitting food to be processed in a shipping
container.
• When food is irradiated, most of the radiation passes through the
food without being absorbed.
• The small amount that is absorbed destroys any insects on grains,
produce or spices, extends shelf life, and prevents fruits and
vegetables from ripening too fast.
• Thus, food irradiation may replace chemical fumigants, sprout
inhibitors, and post harvest fungicides. Higher doses can kill
Salmonella and other harmful bacteria that can contaminate meats
and poultry and cause food borne diseases.
• Food irradiation is a "cold treatment" that achieves its effects
without raising the food's temperature significantly, leaving the food
closer to its original state.
• Even spices which are treated for 2-4 hours remain essentially at
room temperature. By not using high temperatures, food irradiation
minimizes nutrient losses and changes in food texture, color, and
flavor.

13. Gamma rays
• Naturally occurring and man-made radionuclides, also
called radioactive isotopes or radioisotopes, are
unstable, and emit radiation as they spontaneously
disintegrate, or decay, to a stable state.
• The radionuclide used almost always for the irradiation
of food by gamma rays is cobalt-60.
• Radioactive substances emit gamma rays all the time.
When not in use, the gamma ray “source” is stored in a
pool of water which absorbs the radiation harmlessly
and completely.
• To irradiate food or some other product, the source is
pulled out of the water into a chamber with massive
concrete walls that keep any rays from escaping.
• Medical products or foods to be irradiated are brought
into the chamber, and are exposed to the rays for a
defined period of time.
• After it is used, the source is returned to the water tank.

14. • Radiation processing of food is
carried out inside an irradiation
chamber shielded by 1.5 - 1.8 m thick
concrete walls.
• Food either pre-packed or in-bulk
placed in suitable containers is sent
into the irradiation chamber with the
help of an automatic conveyor.
• The conveyor goes through a
concrete wall labyrinth, which
prevents radiation from reaching the
work area and operator room.
• When the facility is not in use the
radiation source is stored under 6 m
deep water.
• The water shield does not allow
radiation to escape in to the
irradiation chamber, thus permitting
free access to personnel to carry out
plant maintenance.
• For treating food, the source is
brought to the irradiation position
above the water level after activation
of all safety devices.
• The goods in aluminium carriers or
tote boxes are mechanically
positioned around the source rack
and are turned round their own axis,
so that contents are irradiated on
both the sides.
The absorbed dose is determined by
the residence time of the carrier or
tote box in irradiation position.

15. • the irradiation room
• A system to transport the food into and out of the
room
• concrete shielding (1.5 - 1.8 metres thick)
surrounding the irradiation room, which ensures
that ionising radiation does not escape to the
outside of the room.

17. Electron Beams
• Since the associated energy levels of these rays
are too low to be practical value in preservation,
they need to be accelerated (in cyclotrons, linear
accelerators etc.) to make them acquire the
required energy.
• Since electrons cannot penetrate very far into
food, compared with gamma radiation or X-rays,
they can be used only for treatment of thin
packages of food and free flowing or falling
grains.

19. • chemical events
as a result of
energy
deposition on
target molecule
Direct
• radicals formed
from the
radiolysis of
water
indirect

20. • The international unit of measurement is the
Gray (Gy).
• One Gray represents one joule of energy
absorbed per kilogram of irradiated product.
One Gy is equivalent to 100 rad (radiation
absorbed dose)
• The desired dose is achieved by the time of
exposure and by the location of the product
relative to the source.
• depend upon the mass, bulk density and
thickness of the food

21. • While the term irradiation pertains to all forms of
treating food products with ionizing radiation,
specific types of radiation treatments are used in the
food industry today.
• RADURIZATION
• RADICIDATION
• RADAPPERTIZATION

22. RADURIZATION
• Radurization is the process of pasteurization
by the use of radiation.
• It is primarily used to treat foods that have a
high moisture content and a highPH
• The microbes that are targeted are mainly
spoilage organisms.

23. • Meat and fish are the foods for which this process is
mainly used.
• For drier, acidic foods, yeasts and molds can be
denatured.
• The treatment dose for radurization is approximately
1 kGy

24. • The process of radicidation is used to eliminate
pathogens. This process kills vegetative cells only,
meaning that it will not kill spores.
•
• Also, certain radiation-resistant vegetative cells can
survive, including some strains of the bacterium
Salmonella which have been found to be radiation-
resistant.
Radicidation

25. • Refrigeration is required for the product post-
treatment.
• The dose for radicidation ranges from 2.5 - 5.0 kGy.
At this level some physical and chemical changes
may be detected, depending on the type of food.
• For example, leafy vegetables such as lettuce are
more sensitive to irradiation than foods with a
tougher consistency

26. • Radappertization involves treating the product to
levels of radiation of approximately 30 kGy.
• This high level of radiation kills all vegetative cells
and also destroys spores from organisms such as
Clostridium botulinum.
• Such levels are generally deemed sufficient for
clinical sterility, but not usually employed on food
items
Radappertization

27. Logo for irradiated food products

30. • The maximum dose of 10 kGy recommended by
the Codex General Standard for Irradiated
Foods is equivalent to the heat energy required
to increase the temperature of water by 2.4ºC.
• Irradiation is often referred to as a ‘’cold
pasteurization’’ process as it can accomplish the
same objective as thermal pasteurization of
liquid foods,
• For example milk, without any substantial
increase in product temperature.

31. • 1895 W. K. Von Roentgen discovers X-rays.
• 1896 H. Becquerel discovers radioactivity.
• 1896 F. Minsch suggests using ionizing radiation to
kill microorganisms in food.
• 1903 M. Curie described 3 different types of
radiation – alpha, beta and gamma.
• 1904 S. C. Prescott publishes effects of ionizing
radiation on bacteria.
• 1905 U.S. and British patents are issued for the
proposed use of killing bacteria in food with ionizing
radiation.
• 1921 B. Schwartz, a researcher at USDA, publishes
studies about the lethal effect of X-rays on

32. • 1943 Preservation of ground beef by exposure to
X-rays demonstrated to be feasible.
• 1950 U.S. Atomic Energy Commission begins
program using radioisotopes for food
preservation.
• 1953 U.S. Army begins food irradiation program.
• 1958 U.S. Federal Food, Drug and Cosmetic Act
is amended, legally defining ionizing radiation as a
food additive rather than a process.
• USSR approves irradiation for potatoes and grain.
• 1960 Canada approves irradiation for potatoes.
• 1963 FDA approves irradiation for insect
disinfestations of wheat and wheat powder.

33. • 1965 FDA approves irradiation to extend the shelf life
of potatoes.
• 1968 FDA and USDA rescind approval for irradiation
of bacon granted in 1963.
• 1976 Joint FAO/IAEA/WHO Expert Committee on the
Wholesomeness and Safety of Food Irradiation
approves several irradiated foods and recommends
that food irradiation be classified as a physical
process.
• 1980 Joint FAO/IAEA/WHO Expert Committee
concludes that any food irradiated up to a maximum
overall average dose of 10kGy presents no
toxicological hazard and requires no further testing.
• 1983 FDA and Canada approve irradiation for insect

34. • 1985 FDA approves irradiation to control
Trichinella spiralis in pork and to disinfest dry
enzyme preparations.
• 1986 FDA approves irradiation to delay ripening
(maturation) of some fruits and vegetables, and
to decontaminate dry or dehydrated enzyme
preparations.
• 1990 FDA approves irradiation to control
pathogens such as Salmonella in fresh and
frozen poultry.
• 1997(FDA) and 1999 (USDA) Approval of
irradiation to control pathogens in fresh and

35. • Wheat flour – control of mold
• White potatoes – inhibit sprouting
• Pork – kill Trichinia parasites
• Fruit and Vegetables – insect control;
increase shelf life
• Herbs and Spices - sterilization
• Poultry – bacterial pathogen reduction
• Meat – bacterial pathogen reduction

36. • Irradiation is a “cold” process, and
therefore…
▫ Little if any change in physical appearance
 No textural or color changes as with
traditional heat preservation
• Possible chemical changes
▫ Off-flavors
▫ Tissue softening

37. Disinfestation
Shelf Life Extension
Decontamination
Product Quality
Improvement

39. • Commercial processing of irradiated potatoes has
been carried out in Japan since 1973.
• important postharvest treatments
• A low dose of 0.15–0.50 kGy can damage insects at
various stages of development that might be
present
• Irradiation can damage insect’s sexual viability or its
capability of becoming an adult
• Radiation disinfestation can facilitate trade in fresh
fruits, such as citrus, mangoes, and papayas which
often harbour insect pests of quarantine importance
(0.2-0.7 KGy)
• a combination treatment of low doses of gamma
irradiation (0.35 kGy). and heat would be

41. • A very low radiation dose of 0.15 kGy or less
(0.02–0.15), inhibits sprouting of products such
as potatoes, yams, onions, garlic, ginger, and
chestnuts.
• Studies have found that the treatment of garlic
bulbs with 0.15 kGy can inhibit sprouting and
reduce weight losses during storage
• Irradiation affects the flavour compounds of
garlic.
• delay the ripening and senescence of some
tropical fruits such as bananas, litchis,

42. • Delay Microbial development in fruits
• Extends the shelf life of perishable products
such as beef, poultry, and seafood by
decontamination of spoilage microorganisms.
• The shelf-life of many fruits and vegetables,
meat, poultry, fish and seafood can be
considerably prolonged by treatment with
combinations of low-dose irradiation and
refrigeration that do not alter flavour or texture.
• Pseudomonas spp., are relatively sensitive to
irradiation. Dose of 2.5 kGy, applied to fresh
poultry carcasses is enough to eliminate

44. • Escherichia coli O157:H7, Salmonella,
Campylobacter jejuni, Listeria monocytogenes, and
Vibrio
• Salmonella and C. jejuni are usually associated with
poultry( 2.5 kGy )
• E. coli O157:H7 has also been linked to meat and
dairy products in the United Kingdom, hamburger
meat, apple juice and water in the USA, and
vegetables in Japan
• Listeria monocytogenes has been associated with
dairy products, processed meats and other foods
having a relatively long shelf-life under refrigeration.

45. • sensitivity of Pathogens to low levels of ionising
radiation
• As the irradiation dose increases more
microorganisms are affected but a higher dose,
introduce changes in sensory qualities and a
balance must be attained between the optimum
dose required
• Eggs and egg products are often contaminated
with Salmonella
• Frozen egg and dried egg could be irradiated at
doses of up to 2- 5 kGy without quality loss and
this dose provides sufficient hygienic protection.
• Seafood (shellfish & frozen shrimp) is often

46. Minimize Food Losses
Improve Public Health
Increase International Trade
An Alternative to Fumigation of
Food
Increase Energy Saving

47. • Irradiation has high
potential in many
cases where food is
spoiled during
postharvest stage
Disinfestation
sprout
inhibition
delayed
ripening

48. • Reduction of:
pathogenic
microorganisms
parasites

49. (i) infestation by
insects
(ii) infection by
microorganisms
(iii) their limited
shelf life
restricts long-distance shipments.

50. Canning
20,180
kJ/kg
Refrigera
tion
17,760
kJ/kg
frozen
storage
46,600
kJ/kg
refrigerate
d &
irradiated
17,860
kJ/kg

51. Effects
of
Irradiatio
n
Proteins
Carbohy
drates
Lipids
Vitamin
s
Enzyme
s

52. peptide
linkages
• not
attacked
sulfur
linkages
• attacked
hydrogen
bonds
• attacked
Low doses : may cause molecular uncoiling, coagulation, unfolding, and
even molecular cleavage and splitting of amino acids
At 10 kGy radiation, overall increase in total free amino acids was
observed mainly due to the rise in the levels of glycine, valine, methionine,
lysine, isoleucine, leucine, tyrosine, and phenylalanine
affects the functional properties of proteins
Egg
loss of viscosity in the white
off-flavors in the yolk
Milk
off-flavors
increase in rennet coagulation time
reduced heat stability

53. • break high-molecular-weight carbohydrates into
smaller units
• softening of fruits and vegetables through
breakdown of cell wall materials, such as pectin
• Sugars may be hydrolyzed or oxidized
• irradiation of wheat at 0.2–10 kGy increase in
initial total reducing sugars and generation of
bread flavor and aroma
• Irradiation of pure carbohydrates produced
degradation products, which have mutagenic
and cytotoxic effects.
• However, these undesirable effects were

54. • initiates the normal process of autoxidation of
fats which gives rise to rancid off-flavors
• The formation of peroxides and volatile
compounds, and the development of rancidity
and off-flavors
• This process can be slowed by the elimination of
oxygen by vacuum or modified atmosphere
• The peroxide formed can also affect certain
labile vitamins, such as vitamins E and K
• The lipids in cereals degraded only at high
doses of irradiation and no significant effects on

55. • The extent of vitamin C, E, and K destruction
depends on the dosage used,
• thiamine is very labile to irradiation.
• The losses are low with low dose
• Ascorbic acid in solution is quite labile to
irradiation but in fruits and vegetables seems
quite stable at low doses of treatment
• Vitamins (antioxidant activity), such as A, B12,
C, E, K, and thiamine, are degraded when
irradiation is carried out in the presence of
oxygen

56. • Enzymes in foods must be inactivated prior to
irradiation because it is much more resistant to
radiation than microorganisms
• complete inactivation of enzymes requires about
5–10 times the dose required for the destruction
of microorganisms
• The D values of enzyme can be 50 kGy and
almost four D values would be required for
complete destruction
• irradiated foods will be unstable during storage
due to their susceptibility to enzymatic attack
than nonirradiated foods

57. • Fruits and Vegetables (Berries, Mangoes,
Carrots, Papaya, Strawberries)
• Spices
• Cereals and Grains
• Animal Foods (Poultry, Mutton, Beef, Pork,
Processed Meats, Fish and Fish Products)

58. promising technology to maintain the quality of fresh fruits
and vegetables because
• it has the potential to control both spoilage and pathogenic
microbes
• physical means for pasteurization without changing the fresh
state
• at a pasteurization dose (2–5 kGy) could control post-harvest
spoilage and diseases
• undesirable symptoms are
• tissue softening
partial depolymerization of cell wall polysaccharides, mainly
Fungal
diseases
pathological
breakdown
insect
infestation.
tissue
damage
this technology should
be used in
combination with
other treatments.

59. • irradiation with heat strong inactivation effect (1%
survival) was obtained when irradiation plus heat
(1.25 kGy 46°C, 5 min)
• Papaya: 48.9°C for 20 min in combination delayed
ripening with optimum dose of 0.75 kGy
• heating and irradiation had a stronger interaction
than heating and chilling
• The oxidation can be minimized by irradiating in an
atmosphere with reduced oxygen content,
• low-dose irradiation combined with modified
atmosphere is increasingly considered for control of
microorganisms and delayed ripening
• Couture and Willemot showed the synergistic action
of irradiation combined with high carbon dioxide for
control of mold development on strawberries. (7%

60. Strawberry 1.5–
2kGy (3 kGy) 14
days.
Papaya &
mango (0.25
-1 kGy)
Mushroom
(2 - 3kGy)
two-fold

61. • Not all fruits and vegetables are suitable for
irradiation because undesirable changes in
colour or texture, or both, limit their acceptability.
• different varieties of the same fruit or vegetable
may respond differently to irradiation.
• The time of harvest and the physiological state
also affects the response of fruits and vegetables
to irradiation
• For delaying ripening in fruits it is important to
irradiate them before ripening starts.

62. Shelf-life of strawberries
can be extended by
irradiation!!!

64. • Spices, herbs and vegetable seasonings are valued
for their distinctive flavours, colours and aromas.
• they are often heavily contaminated with
microorganisms because of the environmental and
processing conditions under which they are
produced (open air drying procedures)
• Before use in food the microbial load should be
reduced.
• Because heat treatment can cause significant loss
of flavour and aroma, a ‘’cold process’’, such as
irradiation, is ideal.
• Until recently, most spices and herbs were
fumigated, usually with sterilizing gases such as
ethylene oxide to destroy contaminating
microorganisms

65. • increasingly important use of irradiation for
decontamination of spices
• A dose of 2.5 kGy reduced the fungal and
bacterial load by 2 log cycles, and 7.5 kGy
eliminated the fungal population of ground or
whole pepper.
Clostridiu
m
Staphyloco
ccus Bacillus
Aspergill
us
Fusarium

66. • Irradiation of spices on a commercial scale is
practised in over 20 countries and global
production has increased significantly from
about 5,000 tonnes in 1990 to over 60,000
tonnes in 1997.
• In the USA alone over 30,000 tonnes of spices,
herbs and dry ingredients were irradiated in
1997 as compared to 4,500 tonnes in 1993.

67. • with low doses of irradiation to eliminate fungi,
since some of these organisms can produce
mycotoxins
• 0.2–1.0 kGy are effective in controlling insect
infestation in cereals
• Increasing the dose to 5 kGy totally kills the
spores of many fungi, which survive lower doses
• loaf volume and baking quality deteriorated
above 5 kGy irradiation irrespective of the
baking formula.

68. • The irradiation is effective in preventing or
delaying the microbial spoilage of fresh meats
and poultry.
• Early studies indicated that irradiation at doses
between 0.25 and 1kGy under aerobic
conditions increased microbiological shelf life,
but accelerated rancidity
• In case of meats, doses up to 2.5 kGy control
Salmonella, Campylobacter, Listeria
monocytogenes, Streptococcus faecalis,
Staphylococus aureus, and Escherichia coli in
poultry and other meats.
• The doses in excess of 2.5 kGy may change

69. • The amount of nitrite required in cured meats
possibly can be reduced by irradiation, thus the
chance of nitrosamine formation can be lowered
• can be reduced from normal levels of 120–150
to 20–40 mg/kg without loss of organoleptic
quality

70. • control of pathogenic organisms and the
extension of shelf life of fresh fish could be
achieved with relatively low doses 2.5 kGy
• Clostridium botulinum (A, B, E, and F) present in
fish and fish products remained unaffected by
the low doses of irradiation.
• Thus, precautions during storage under 3°C and
oxygen availability to the product need to be
taken

71. • As irradiation is a cold process does not
substantially raise the temperature of the food
being processed,
• nutrient losses are small and often significantly
less than losses associated with other methods
of preservation such as canning, drying and
heat pasteurization.

73. • Production of gas and volatiles compounds, which may migrate
into the food and cause off-flavors.
• At sterilizing doses, nylon gives rise to little off-odor production,
• in case of polyethylene, short fragmentations of the polymer are
produced, which enter the food
• Volatile compounds are formed in polyethylene, polyester
terephthalate, and oriented polypropylene after irradiation dose
from 5 to 50kGy.
• Twenty-two compounds (polyester terephthalate), 40 (oriented
polypropylene), and only acetone was identified for
polyethylene, which could be a good candidate for irradiation
of packaged food products.
• These compounds are hydrocarbons, ketones, and aromatic
compounds

74. The properties of polyethylene terephthalate (PET) are
well preserved during irradiation
At doses of 60 kGy and higher, some damage may
occur in tin-coated steel and aluminum containers, but at
the level of sterilizing doses there should not be any
affect
At doses less than 20kGy, physical changes in flexible
containers are negligible.
High doses above 30 kGy cause brittleness in
cellophanes, saran, and plioform, while 20 kGy or more
can cause inconsequential physical changes in mylar,
polyethane, vinyl, and polyethylene plastic films
At strong doses of 50kGy, mechanical properties of
polymers can be improved by cross-linking

76. • has a low operating cost
• requires low energy
But:
high capital costs
requires a critical minimum capacity
At low doses all microorganisms and their toxins
will not be eliminated and above threshold
doses, organoleptic changes and off-flavor will
develop.
Limitation in packaging material