l          Food and Agriculture Applications 

One of the popular applications of nuclear technology is food irradiation.  Food irradiation can eliminate bacteria, insects and parasites that can cause food-borne diseases, such as salmonella, trichinosis and cholera. In addition, irradiation can slow down spoilage and increase the shelf life of food.

The irradiation process exposes food to gamma rays from cobalt-60 which is a radioisotope of cobalt. Gamma rays are a form of electromagnetic energy, just like radio waves, microwaves, X-rays and even light. Gamma rays have the ability to penetrate well into a food. Machine-generated X-rays have similar properties. More recently, electron beams (e-beams) have become available as a source of ionizing energy in the USA and other countries. Like X-rays, e-beams are machine-generated using ordinary electricity and can be powered on and off at the touch of a switch. E-beams offer extremely rapid and cost-effective processing, but in some cases sacrifice penetration depth depending on product density. Treatment of food using either X-rays or electron beams are occasionally referred to as “electronic pasteurization” or “electronic irradiation” methods because they are derived from electricity.

Regardless of the source of ionizing energy, the food is treated by exposing it to the energy source for a precise time period. In the case of e-beam, food is irradiated in just a few seconds, while it takes gamma and X-rays considerably longer. The food is never in contact with the energy source; the ionizing energy merely penetrates into the food but does not stay in the food. It takes very little energy to destroy harmful bacteria. At these levels there is no significant increase in temperature or change in composition. Irradiation does not make food radioactive nor does it leave any residues.

Irradiation does not change the food any more than canning or freezing.  All known methods of food processing and even storing food at room temperature for a few hours after harvesting can lower the content of some nutrients, such as vitamins. At low doses of radiation, nutrient losses are either not measurable or, if they can be measured, are not significant. At the higher doses used to extend shelf-life or control harmful bacteria, nutritional losses are less than or about the same as cooking and freezing.  Independent scientific committees in USA, Denmark, Sweden, United Kingdom and Canada also have reaffirmed the safety of food irradiation. In addition, food irradiation has received official international endorsement from the World Health Organizations and the International Atomic Energy Agency.  In the United States, the U.S. Food and Drug Administration has approved the use of irradiation for fruits, vegetables, pork, poultry, red meat and spices.  In addition, more than 40 countries have also approved the use of radiation to help preserve nearly 40 different varieties of food.  

In agriculture, radiation had eradicated approximately 10 species of pest insects in wide areas, preventing agricultural catastrophes. These pests included the Mediterranean fruit fly and the screwworm fly.  The technique used for eradicating the aforementioned insects is the sterile insect technique which is a method of biological control, whereby millions of insects sterilized with radiation, are released. The released insects are normally male as it is the female that causes the damage, usually by laying eggs in the crop, or, in the case of mosquitoes, taking a bloodmeal from humans. The sterile males compete with the wild males for female insects. If a female mates with a sterile male then it will have no offspring, thus reducing the next generation's population. Repeated release of insects can eventually wipe out a population, though it is often more useful to consider controlling the population rather than eradicating it.

Agricultural researchers also use radiation to:

• develop hundreds of varieties of hardier, more disease-resistant crops—including peanuts, tomatoes, onions, rice, soybeans and barley;
• improve the nutritional value of some crops, as well as improve their baking or melting qualities or reduce their cooking time;
• pinpoint where illnesses strike animals, allowing the breeding of disease-resistant livestock;
• show how plants absorb fertilizer, helping researchers to learn when to apply fertilizer, and how much to use; this prevents overuse, thus reducing a major source of soil and water pollution.

References:

Ø      Robert J. Woods, “Food irradiation”, Endeavour, Volume 18, Issue 3, 1994, Pages 104-108

Ø      Johannes Friedrich Die, “Will irradiation enhance or reduce food safety?”, Food Policy, Volume 18, Issue 2, April 1993, Pages 143-151

Ø      L. H. Wedekind, “Food irradiation in Asia and the Pacific”, Food Policy, Volume 11, Issue 4, November 1986, Pages 285-288

Ø      S. V. Nerpin, V. M. Prokhorov and V. N. Savin, “Use of isotopes and nuclear radiation in agricultural research “, Atomic Energy, Publisher Springer New York, ISSN 1063-4258 (Print) 1573-8205 (Online), Issue Volume 26, Number 2, February, 1969, pp. 161–165

Ø      http://www.osti.gov/bridge/servlets/purl/840065-Jhd7iT/native/840065.pdf

Ø      http://www.iaea.org/nafa/d5/index.html

Ø      http://physics.isu.edu/radinf/food.htm