1  What is radiation processing of food ?

Radiation processing of food involves the controlled application of energy from ionizing radiations such as gamma rays, electrons and X-rays for food preservation. Gamma rays and X-rays are short wavelength radiations of the electromagnetic spectrum which includes radiowaves, microwaves, infrared, visible and ultra violet light. Gamma rays are emitted by radioisotopes such as Cobalt-60 and Caesium-137 while electrons and X-rays are generated by machines using electricity.

Electromagnetic Spectrum: Gamma rays are a part of the electromagnetic spectrum. They can penetrate deep into food materials and bring about desired effects

How irradiation works ?

Irradiation works by disrupting the biological processes that lead to decay. In their interaction with water and other molecules that make up food and living organisms, radiation energy is absorbed by the molecules they contact. The reactions with the DNA cause the death of microorganisms and insects and impair the ability of potato and onion to sprout.

3  How do you irradiate food ?

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. Absorbed dose is checked by placing dosimeters at various positions in a tote box or carrier.

A typical Food Irradiation Plant

4  What are the advantages of radiation processing of food ?

Irradiation is a cold process and can be used to pasteurize and sterilize foods without causing changes in freshness and texture of food unlike heat. Unlike chemical fumigants, irradiation does not leave any harmful toxic residues in food and is more effective. It is efficient and can be used to treat prepacked commodities.

5  Does the irradiation process make food radioactive ?

No.  The irradiation process involves passing of food through a radiation field allowing the food to absorb desired radiation energy. The food itself never comes in contact with the radioactive material. Gamma rays, X-rays and electrons prescribed for radiation processing of food do not induce any radioactivity in foods.

6  What is the difference between the terms "Irradiated" and "Radioactive" food ?

Radiation processed foods are those that have been exposed to radiation as prescribed above to bring about the desired effect in food. Radioactive foods, on the other hand, are those that become contaminated with radionuclides. This type of contamination never occurs during food irradiation.

7  What are the chemical changes in radiation processed foods and are they harmful ?

Irradiation produces very little chemical changes in food. None of the changes known to occur have been found to be harmful. The radiolytic products and free radicals produced are identical to those present in foods subjected to treatment such as cooking, canning etc. Highly sensitive scientific tests carried out during the past 30 years have failed to detect any new chemical product in radiation processed foods.

Do the free radicals or radiolytic products which are produced during irradiation affer the safety of food ?

No. There is no evidence to suggest that free radicals or radiolytic products affect the safety of radiation processed food. This has even been confirmed by many long term multi-generation studies in which laboratory animals were fed irradiated products exposed up to a dose of 45 kGy.

9  Does irradiation adversely affect the nutritional value of food ?

No. In comparison to other food processing and preservation methods the nutritional value is least affected by irradiation. Extensive scientific studies have shown that irradiation has very little effect on the main nutrients such as proteins, carbohydrates, fats and minerals. Vitamins show varied sensitivity to food processing methods including irradiation. For example, vitamin C and B1 (thiamine) are equally sensitive to irradiation as well as to heat processing. Vitamin A,E,C,K and B1 in foods are relatively sensitive to radiation, while riboflavin, niacin, and vitamin D are much more stable. The change induced by irradiation on nutrients depends on a number of factors such as the dose of radiation, type of food, and packaging conditions. Very little change in vitamin content is observed in food exposed to doses up to 1 kGy. The Joint Expert Committee of the Food and Agriculture Organization (FAO), World Health Organization (WHO), and International Atomic Energy Agency (IAEA), in 1980 concluded that irradiation does not induce special nutritional problems in food.

10  Does consumption of radiation processed food cause chromosomal abnormalities ?

National Institute of Nutrition (NIN), Hyderabad reported that the feeding of radiation processed food caused development of abnormal chromosomes (Polyploidy) in malnourished children and laboratory animals. Polyploidy means occurrence of cells having more than twice the normal number of chromosomes. Human cells normally have 46 chromosomes. Some polyploid cells may naturally occur in human body. The NIN reported the incidence of “polyploidy” after feeding of products made from wheat immediately after irradiation. No polyploidy was observed when irradiated wheat was stored for 12 weeks before consumption. However, a number of institutions in India and abroad could not reproduce these results. In 1976, a committee appointed by the Government of India examined the NIN data and concluded that neither the design of the study nor the results were such as to demonstrate induction of polyploidy due to consumption of radiation processed wheat. A number of researchers and scientific committees in Australia, Canada, Denmark, France, United Kingdom, United States, and a Joint FAO/IAEA/WHO Expert Committee on the Wholesomeness of Irradiated Food have also evaluated the NIN data and rejected their claims.

11  Are there any human feeding studies of radiation processed foods ?

Yes. In the early 1980s, eight feeding studies using several radiation processed food items, including wheat, were conducted in China with human volunteers, More than 400 volunteers consumed radiation processed food under controlled conditions for 7-15 weeks. Results showed no significant differences between the control and the test groups. Incidence of polyploidy was within the normal range in participants irrespective of consuming irradiated or non-irradiated diet.

12  Can radiation processing of food lead to increased microbiological hazards ?

No. The microbiological safety of radiation processed foods has been carefully scrutinized by international scientific bodies. It has been shown beyond doubt that irradiation can neither increase the infectivity of pathogenic microorganisms nor help them to “grow better” in radiation processed foods. Like in other processing methods, adequate care in packaging, handling and storage are necessary for ensuring safety of radiation processed foods.

13  Can irradiation be used to destroy microbial toxins and pathogenic viruses in food ?

No. As in many other food processing procedures only food of good hygienic quality should be irradiated. It is very important that foods intended for processing are of good quality and handled and prepared according to good manufacturing practice (GMP) established by national and international standards.

14  Can irradiation be used to make spoiled food good, or to clean up "dirty foods" ?

No. Like any other food treatment irradiation can not reverse the spoilage process and make bad food good. A food that looks, smells and tastes bad, cannot be saved by any treatment including irradiation.

15  Does radiation processing of food that contain pesticide residues or additives present any health hazard ?

No. There is no scientific evidence to indicate any health hazard associated with radiation processing of food containing pesticide residues and additives. In the United States, the Food and Drug Administration (FDA) has calculated that the total yield of radiolytic products from the pesticide residue would be virtually negligible.

16  Is there any risk in irradiating foods in contact with plastic or other packaging materials ?

No. Results of extensive research have shown that almost all packaging materials currently used in food industry are suitable for irradiation. Many packaging materials including laminated plastic films with aluminium foil used for packaging of foods are routinely sterilized by irradiation.

17  Can an accident at a food irradiation facility lead to "Meltdown" of the irradiator and release of radioactivity
      that would contaminate the environment and endanger people living nearby ?

No. It is impossible for a “melt down” to occur in a gamma irradiator. A radiation facility can not explode as Cobalt-60 is not a fissionable material and no neutrons are produced unlike in a nuclear reactor. Also no environmental contamination due to leakage of radioactivity can occur because the radioisotope is doubly encapsulated in stainless steel tubes.

No. It is impossible for a “melt down” to occur in a gamma irradiator. A radiation facility can not explode as Cobalt-60 is not a fissionable material and no neutrons are produced unlike in a nuclear reactor. Also no environmental contamination due to leakage of radioactivity can occur because the radioisotope is doubly encapsulated in stainless steel tubes.

18  Do food irradiators have radioactive west disposal problem ?

No. Cobalt-60 and Caesium-137 which are used as the source of radiation energy decay over many years to nonradioactive Nickel and Barium, respectively. When the radioactivity falls to a low level the source pencils are returned to the supplier who has the option of reactivating them in a nuclear reactor or of storing them.

19  How irradiation process is controlled to ensure that foods are properly treated ?

Laws and regulations enacted by Atomic Energy Regulatory Board govern operations of irradiators used to process non-food products, such as medical supplies. Three such irradiators are operating in India and about 160 around the world. The plants which must be approved by the Government before construction, are subject to regular inspection, safety audits, and other reviews to ensure that they are safely and properly operated. Similar controls would be applicable for radiation processing facilities. At the international level, the Codex Alimentarius Commission, of the United Nations Food and Agriculture Organization (FAO) and the World Health Organization (WHO) have laid down standards for good manufacturing practices (GMP) and good irradiation practices (GIP) for a number of foods. They cover all aspects of treatment, handling, storage and distribution of food. The guidelines emphasize that, as with all food preservation techniques, effective quality control systems need to be installed and adequately monitored at critical control points at the irradiation facility.

20  Are there any tests to detect whether food has been irradiated ?

Yes. There are specific tests developed for certain class of foods. However, no single method has yet been developed that reliably detects irradiation of all types of foods or radiation dose levels applied. Thermoluminescence measurement and electron spin resonance spectroscopy can be used for detecting radiation processed spices and meat containing bone tissue.

21  Will irradiation increase the cost of food ?

Any processing will add to the cost of food. In most cases, however, food prices may not necessarily rise just because a product has been treated. Many variables affect food costs, and one of them is cost of processing. But processing also brings benefits to consumers in terms of availability, storage life, distribution, and improved hygiene of food. Irradiation can have a stabilizing effect on market price of commodities by reducing storage losses resulting in increased availability of produce. Irradiation costs may range from Rs.0.25 to 0.50 / kg for a low dose application such as sprout inhibition of potato and onion and insect disinfestation in cereals and pulses to Rs.1-3/kg for high dose applications such as treatment of spices for microbial decontamination. The costs could be brought down in a multipurpose facility treating a variety of products around the year.

22  How much a typical radiation processing facility costs ?

Estimated cost of a commercial radiation processing facility is in the range of Rs.6-8 crores.

23  Is it true that consumer is opposed to buying radiation processed foods ?

No. Consumer research and market tests in several countries including USA, South Africa, The Netherlands, France, Thailand, China, etc. have shown that consumers accepted radiation processed products when factual information about the benefits of the technology was provided to them. Consumers willingly bought, and in many cases, expressed preference for the radiation processed products.

24  Are radiation processed foods being sold on a regular basis in the market ?

In some countries, such as France, The Netherlands, South Africa, United States, Thailand and China, commercial quantities of some radiation processed food items - strawberries, mango, banana, shrimp, frog legs, chicken, spices, and fermented pork sausages - are being sold on regular basis on the market shelf. Besides, more than 23 countries are irradiating food for processing industries and institutional catering. These radiation processed food items are labeled to indicate the treatment and its purpose.

Radiation processed Foods on Sale in a U.S. Market. Irradiated products are marketed on a commercial scale in the United States. Several other countries also market irradiated foods.

25  How has the safety of radiation processed food been tested ?

The safety of radiation processed food has been ascertained using an internationally accepted wholesomeness testing protocol. The investigations include checking for induced radioactivity, monitoring changes in microflora, presence of any of mutant forms of microbes; assessing nutritional adequacy of irradiated foods by studying proximate analysis, vitamin losses, study of amino acids, protein efficiency ratio and in vitro digestibility; studying the chemical constituents of irradiated foods to rule out the possibility of any toxic compounds; and finally the multi-generation feeding studies lasting for 3-4 generations in at least two mammalian species. One third of the animals are studied in detail for vital characteristics such as growth, reproduction, hematology, longevity, histopathology, presence of cancer and mutations. Many animal feeding studies have been carried out with radiation processed foods. One of the most notable was a six year animal feeding study with high-dose irradiated chicken that was conducted for the U.S. Army and the U.S. Department of Agriculture. More than 600,000 pounds of chicken were fed to several generation of test mice, hamsters, rats, rabbits, and dogs. It was concluded that radiation sterilized chicken would pose no toxicological hazard to humans.

26  Where cam food be irradiated ?

Food can be irradiated in a radiation processing plant which is authorized by the Atomic Energy Regulatory Board and licenced by the competent authority. The licence to carry out radiation processing of food is given only after ascertaining the safety of the installation, its suitability to ensure proper process control, and availability of licenced operators and qualified staff. A facility could be put up as a private, public or joint sector company.

27  What is the world status of the technology of radiation processing of food ?

The volume and number of radiation processed food products entering trade has grown steadily in recent years, particularly in China, Belgium, France, The Netherlands, South Africa and the United States. Over 100000 tonnes of food material were irradiated in 1995.

28  What is the status of the technology of radiation processing of foods in India ?

In 1994 Government of India approved irradiation of onion, potato and spices for internal marketing and consumption. There is a small pilot scale Food Package Irradiator at Food Technology Division, Bhabha Atomic Research Centre, Mumbai, which can treat up to 500 kg of onion and potato per hour. The Department of Atomic Energy is constructing two demonstration facilities for food irradiation. A facility for technology demonstration purpose will be soon commissioned for irradiation of spices at Vashi, Navi Mumbai. Another demonstration facility for irradiation of potato and onion is being set up at Lasalgaon in Nashik District.

29  Why irradiate spices ?

Most spices get heavily contaminated with microbes including pathogenic bacteria during sun drying. Contamination arises from deposition of excreta of insects, birds, rodents and other animals and from wind blown dust containing these microbes. Naturally present mold spores can grow under high humidity storage conditions and lead to formation of aflatoxins and other mycotoxins. It can also lead to caking and spoilage. Insect infestation is another major problem in stored spices often resulting in losses up to 20-25%.

30  How can radiation processed foods be identified in the market ?

Radiation processed food cannot be recognized by sight, smell, taste or touch. Codex Alimentarius Commission has endorsed a green irradiation logo. As per the PFA (Fifth Amendment) Rules, 1994, all packages of irradiated foods to be marketed in India will be labeled with this logo, along with the words “Processed by irradiation method”, and the date of irradiation, licence number of the facility and the purpose of irradiation. Consumers will have a free choice to buy irradiated or non-irradiated commodity.