1. A Brief History of Food Irradiation
1905 Begins the era of food irradiation.
1958 Congress defines a source of radiation as a food additive.
1980 Foods irradiated up to 10 kGy considered to be safe and wholesome.
1997 Foods irradiated at any dose should be considered as safe and as wholesome as foods treated by any other conventional process.
2001 Irradiation is used to eliminate possible traces of Anthrax.
FDA approves the use of irradiation in a variety of foods.
1905 Scientists receive patents for a food preservation process that uses ionizing radiation to kill bacteria in food.
1921 A U.S. Patent is granted for a process to kill Trichinella spiralis in meat using x-rays.
Animal feeding studies are performed to assess the wholesomeness of irradiated food.
1943 Scientists at the Massachusetts Institute of Technology show that x-rays can be used to preserve ground beef.
1950’s Beginning of era of food irradiation in the U.S. and Europe, with studies involving wholesomeness and application of the technology dominating the research.
1953 Formation of the U.S. National Food Irradiation Program, a project of the U.S. Army and the Atomic Energy Committee.
The Army Medical Department oversees a program to study the safety and wholesomeness of 21 irradiated foods. The Army Surgeon General concludes that foods irradiated up to a specific dose pose no significant health risks to humans.
1958 Congress classifies irradiation as an additive; therefore, a food additive petition detailing each application is required before irradiation can be used.
1976 The Joint Expert Committee on the Wholesomeness of Foods, formed by the World Health Organization, International Atomic Energy Agency, and Food and Agriculture Organization of the United Nations, convenes with scientists and other experts to recommend that food irradiation should be classified as a process, not an additive.
1980 The Joint Expert Committee designates that foods irradiated up to 10 kGy be considered safe and wholesome.
1997 The Joint Expert Committee designates that foods irradiated at any dose should be considered as safe and as wholesome as foods treated by any other conventional process.
2001 Irradiation is used by the U.S. Postal Service to eliminate possible traces of Anthrax. Consumers begin to understand the technology and acceptance grows.

2. Radiation Spectrum

4. E-beam – shallow penetration Gamma – ‘deeper’ penetration
Method of Action
E-beam – shallow penetration
Converted to x-ray for more penetration
Gamma – ‘deeper’ penetration
All act via similar mechanisms

5. UV Radiation
Effective at microbial decontamination in liquids.
Approved for use in surface decontamination.
Approved for use in juices.

6. Accelerated electrons: The electron beam - a stream of high energy electrons out of an electron gun.
This electron gun apparatus is a larger version of a standard television tube.
There are no radioactive materials in the process. The electrons can penetrate food only to a depth of three centimeters.
Two opposing beams can treat food that is twice as thick. E-beam medical sterilizers have been in use for at least fifteen years.
Gamma rays: The radionuclide used for the irradiation of food by gamma rays is cobalt-60.
produced by neutron bombardment of cobalt-59 in a nuclear reactor.
they are doubly encapsulated in stainless steel “pencils” to prevent any leakage.
Cobalt-60 has a half-life of 5.3 years.
This technology has been used forty years to sterilize medical, dental and household products, and it is also used for radiation treatment of cancer.
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.
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.

7. IRRADIATOR UNIT

8. Dose Irradiation doses are measured in gray (Gy)
Gy is measured in joule/kg absorbed energy
1 Gy = 1J/kg over an area of 1 m2 / s2
For X-rays and gamma rays =, the unit is Sievert
Energy sources are constant
Applied dose = energy source x time exposed

9. Bacterial Susceptibility
All bacteria have different susceptibilities to radiation (values in kGy)
Salmonella spp. –
Listeria monocytogenes –
E. coli O157:H7 –
A % reduction = 5 x D10 value
Jejuni – common poultry

10. Sources of Radiation
Cobalt MeV
Cesium  keV
Electron accelerators operated at
10 MeV or less
X-ray generators operated at
7.5 MeV or less

11. Low Dose (<1 kGy) Medium Dose (1-10 kGy) High Dose (> 30 kGy)
Types of Irradiation
Low Dose (<1 kGy)
Control insects
Inhibit maturation
Inhibit sprouting
Medium Dose (1-10 kGy)
Extend shelf life
Reduce microorganism level
High Dose (> 30 kGy)
Sterilize - analogous to canning
Decontaminate certain food additives, e.g., spices

12. ECONOMICS OF RADIATION PROCESSING OF FOODS
The design of the facility and therefore the economics depend on the parameters associated with radiation processing of food.
These parameters include dose range, nature of food product, density of product, irradiator efficiency, annual operating hours, throughput, Cobalt-60 loaded, replenishment of Cobalt-60 required and the number of handlers employed, besides capital cost and cost of operation, maintenance, etc .
In general a radiation processing facility may cost between 5-10 crores. The cost of processing charged to product is expected to be less than 5% of the cost of the commodity.

13. Heated Lipid (180 ºC/1Hr) vs Irrad (120 kGy)

14. Labeling Criteria
The FDA requires that irradiated foods bear the radura label and state on the label “Treated with radiation” or “Treated by irradiation”
There is no statutory requirement specific to irradiation