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

2

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

4

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

5

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

8

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

10

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)

26

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)

29

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….