IRRADIATION OF VEGETABLES
Ningappa Kirasur
2014-12-129
Dept. of Olericulture
1
What is Food Irradiation?
Food irradiation is the process of exposing food to an ionizing
energy to kill harmful bacteria and other organisms. To extend
Shelf-life of produce
It is a safe process and approved by more than 50 countries
Applied commercially in USA, Japan, and several European
countries for many years
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History of food irradiation
1920-French scientists discover irradiation of preserves foods
1940-U.S. Army begins testing irradiation on common foods
1963-Irradiation is approved by the U.S. government to control
insects in wheat and wheat powder
1964-Government approves irradiation to extend shelf life of
white potatoes
1983-Spices and dry vegetable seasonings approved for
irradiation to kill insects and bacteria
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Radiation sources
Gamma rays from radio nuclides 60co or 137cs
X-rays – generated from machine sources operated at
below an energy level of 5MeV
Electrons – from machine sources operated at below an
energy level of 10MeV
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Contd….
• Treatment of food using either X-rays or electron beams are
referred as “electronic pasteurization”
• The food is treated by exposing it to the energy source for a
precise time period
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Contd…
In the case of e-beam, food is irradiated in just a few seconds
While gamma rays and X-rays considerably take longer time
The ionizing energy merely penetrates into the food but does
not stay in the food
It takes very little energy to destroy harmful bacteria
The levels of ionizing energy used to treat foods for pathogen
reduction are measured in kilo Grays (kGy) 6
Types of applications based on dose of radiation
o Low Dose Applications (up to 1 kGy)
o Medium Dose Applications (1 kGy to 10 kGy)
o High Dose Applications (above 10 kGy)
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Various applications of irradiation doses
Name of food material
purposes Minimum dose (KGy)
Maximum dose(KGy)
Onion Sprout inhibition 0.03 0.09
Potato Sprout inhibition 0.06 0.15
Garlic Sprout inhibition 0.03 0.15
Shallots Sprout inhibition 0.03 0.15
fruits Delay ripening 0.25 0.75
spices Microbial decontamination 6 14
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Status of food irradiation in India
In 1994 Government of India approved irradiation
For onion, potato and spices for internal marketing and
consumption
Food Package Irradiator at Food Technology Division ( BARC )
treat 500 kg /hr at Department of atomic energy
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Irradiation Processing plant
An irradiation chamber shielded by 1.5 - 1.8 m thick concrete walls
The food pre-packed or in bulk placed in suitable containers is sent
into the irradiation chamber using automatic conveyor
The radiation source is stored under 6 m deep water
Source is brought to the irradiation position above the water level
after activation of all safety devices
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Contd…
• The goods in aluminium carriers are mechanically positioned
around the source rack and are turned round their own axis
• Absorbed dose is checked by placing dosimeters at various
positions in a tote box or carrier
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Benefits of Food Irradiation
• Reduces food borne disease
• Reduces food spoilage/increase food supply
• Reduces insect infestations
• Prevent sprouting/delay ripening
• Reduces use of fumigants
• Cheaper than freezing and refrigeration
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FDA Food Safety Concerns
Vitamins are most sensitive to radiation
Very dependent on dose, temperature and food type
Low temperature and no oxygen are best
Enhance nutrition in case of water soluble vitamins
No vitamin deficiency from eating irradiated foods
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Irradiated Food Safety: WHO
o No adverse toxicological effects on human health
o No increased microbiological risk
o No adverse effects on nutritional status
o Irradiated foods are safe
o wholesome at any radiation dose
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How Widespread of Food borne Illness?
Food borne illness outbreaks have been associated with every
food commodity
Dairy products, eggs, meats, seafood, fruits and vegetables
Outbreaks can occur because of cross contact during food
handling, processing and home preparation
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Contd…
The impact of food borne illness on health in the United States
The Centers for Disease Control and Prevention estimates
Food borne illness causes 5,000 deaths each year or
approximately 100 deaths per week
Pathogens such as Salmonella, Listeria and Taxoplasma
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Internationally renowned organizations
World Health Organization (WHO)
The American Medical Association (AMA)
The American Dietic Association (ADA)
o Have embraced this technology for the food safety benefits
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What are Consumer’s reactions?
Consumers are enthusiastic about purchasing clearly labeled
irradiated food
Irradiated foods, safety and taste more important than price
They believed that eliminating harmful bacteria was a more
valuable benefit and than extended shelf-life
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Contd…
o Consumers who prefer organic foods will not have the option
of buying irradiated organic produce
o If it costs more, most consumers would probably not buy it for
long, unless they believe
o Acceptability rates ranging from 45% to 90%, depends on the
food type and method of presentation Nayga et al. (2004)
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Contd…
It is easy for consumers to determine, if a food has been
irradiated
Regulations requires that irradiated food must be labeled
As an international food irradiation logo
Such as “treated with radiation” or “treated by irradiation.”
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Is Food Irradiation Safe?
Yes. Food has been irradiated in several countries for many
years resulting safer for consumption than the untreated
original foods
Food irradiation provides an added layer of protection to food
without significant changes to taste, nutritional value, color or
texture
22
Contd…
o Consumers must practice safe food handling techniques, the
food is irradiated or not
o It is still possible for bacteria to multiply in irradiated food
o If it has been not refrigerated properly
o If care is not taken to avoid cross contamination with harmful
bacteria from other sources
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Does irradiation affect nutritional quality?
• Irradiation could adversely affect the nutritional quality of
foods
• High-energy ionizing radiation that breaks molecules might
destroy vitamins in fruits and vegetables
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Irradiation affect the sensory quality of produce?
Degrade the appearance and sensory quality of many fresh
fruits and vegetables
The effects of irradiation on the quality of fresh fruits and
vegetables
A dose of irradiation high enough to reduce bacterial load
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Case studies
Irradiated sliced green onions at doses ranging from 0.5 to 3 kGy
Doses greater than 1.5 kGy caused loss of aroma and visual
quality
Lower doses of radiation (0.5, 1.0 and 1.5 kGy) reduced
bacterial loads
While colour, texture and aroma were preserved
Fan et al. (2003a)
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Contd….
Irradiated 13 types of fresh-cut vegetables at dosages ranging
from 0.5 to 3 kGy
Measured tissue damage by electrolyte leakage
Green onions, celery, red lettuce and carrots were the most
sensitive
Broccoli, endive and red cabbage were the most resistant
Fan and Sokorai (2005)
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Contd...
o Spinach, romaine lettuce, iceberg lettuce, parsley and green
leaf lettuce were intermediate in sensitivity
Fan and Sokorai (2005)
o Irradiation improves the nutrient content of lettuce
o The irradiated lettuce showed greater browning than controls
o Effect of the increased phenolic content
Fan et al.,(2005a)
28
Contd….
Irradiation doses greater than 1 kGy caused softening (loss of
crispyness), browning and decreased vitamin C content in lettuce
When lettuce irradiated at 0.5 and 1.0 kGy was dipped in hot
water at 47oC
Reduced bacterial loads without effects on vitamin C content
(Fan et al. 2003b)
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Contd…
• Choosing an optimal dose for particular items can be more
difficult
• Uneven irradiation - irregular shapes and variable textures of
vegetables
• When irradiation doses are absorbed unevenly, some areas in the
food get too low doses
• It difficult to control pathogens effectively
(Niemira and Fan 2006)
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Food Irradiation Concerns: Non-Food Related
o Radiation hazardous to workers or public
o Increased risk of nuclear accidents
o Add nuclear wastes
o Radiation resistant microbes
o Effect on environment and ground water polluion
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Food Irradiation: The Future
Implementing irradiation in food processing industries
Develop suitable packaging methods
Develop methods to detect irradiated foods
Education to public
Additional research
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Identification of irradiated food
Codex Alimentarius
Commission has endorsed a
green irradiation logo.
The Radura is the international
symbol indicating a food
product has been irradiated.
All packages of irradiated
foods- labelled with this logo
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Irradiated vegetables
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Contd….
Thank U….