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Food Technology Division

FOOD PRESERVATION BY RADIATION PROCESSING 

NEED TO PRESERVE FOOD

Food is vital for human existence. Conservation and preservation of food is a prerequisite for food security and it provides economic stability and self-reliance to a nation. 

The need to preserve food has been felt by mankind since time immemorial. The seasonal nature of production, long distances between production and consumption centres and rising gap between demand and supply have made this need even more relevant today. The hot and humid climate of a country like India is quite favourable for the growth of numerous insects and microorganisms that destroy stored crops and cause spoilage of food every year. Spoilage can also occur due to chemical and physiological changes in stored foods. Sea-foods, meat and poultry may carry harmful microbes and parasitic organisms that cause illnesses associated with their consumption. As in other parts of the world, India has also practiced various methods of food preservation such as sun drying, pickling and fermentation which were supplemented with more energy consuming techniques such as refrigeration, freezing and canning. Each of these methods has its merits and limitations. Man has always been on the search for newer methods to preserve foods with least change in sensory qualities. Radiation processing of food is one of the latest methods developed for this purpose. 

Radiation processing of food involves exposure of food to short wave radiation energy to achieve a specific purpose such as extension of shelf-life, insect disinfestation and elimination of food borne pathogens anparasites. In comparison with heat or chemical treatment, irradiation is considered a more effective and propriate technology to destroy food borne pathogens. It offers a number of advantages to producers, processors, retailers and consumers.Radiation processing of food involves exposure of food to short wave radiation energy to achieve a specific purpose such as extension of shelf-life, insect disinfestation and elimination of food borne pathogens and parasites. In comparison with heat or chemical treatment, irradiation is considered a more effective and appropriate technology to destroy food borne pathogens. It offers a number of advantages to producers, processors, retailers and consumers. 

 

Major Features

 

Food Preservation by Radiation Processing
Safety and Nutritional Adequacy of Radiation Processed Foods
Application of Radiation Processing of Food
Benefits and Limitations of Radiation Processing of Food 
Consumer Responses
Control & Regulations
Economics of Radiation Processing of Foods
Know-How and Technology Transfer 
International Status
Frequently Asked Questions
 

For further information write to: 
Head 
FOOD TECHNOLOGY DIVISION 

BHABHA ATOMIC RESEARCH CENTRE 
Mumbai-400085 

Phone: 25505180, 25592539 
Telex: 011-61022 BARC IN 
Fax : 91-22-25505151 / 25519613 
ftd@barc.gov.in


SAFETY AND NUTRITIONAL ADEQUACY OF RADIATION PROCESSED FOODS

No other method of food processing has been subjected to such a thorough assessment of safety as the radiation processing method. The various aspects of wholesomeness and safety of radiation processed foods have been studied in great detail in scientific laboratories of the world. These results have been reviewed by the experts of the World Health Organization (WHO), Food and Agricultural Organization (FAO), and International Atomic Energy Agency (IAEA) and also independently by the governments of various countries. The tests for wholesomeness and safety of radiation processed food include, checking for induced radioactivity, microbiological safety, safety of chemical changes, nutritional adequacy, and feeding studies on animals and humans. 
At the energies of the gamma rays from Cobalt-60 and those recommended for X-rays and accelerated electrons, no radioactivity can be induced in foods. The microbiological aspects of radiation processed foods have been studied in detail. None of the studies have indicated that foods preserved by radiation pose any special problems in relation to microorganisms. The chemical differences between radiation processed foods and non-irradiated foods are too small to be detected easily. The rough composition of food remains largely unchanged, some losses in certain vitamins may be encountered. Such losses are however also encountered with other methods of food processing. The losses are often minor and could be made up from other sources. Animal feeding studies have been the most time consuming and expensive feature of wholesomeness testing. None of the short- or long-term feeding studies on animals and trials on human volunteers have shown any adverse effects of consumption of radiation processed foods. 

In 1980 a joint FAO/IAEA/WHO Expert Committee on Food Irradiation (JECFI) reviewed the extensive data on wholesomeness collected up to that time and concluded that irradiation of any commodity up to an over all dose of 10 kGy presents no toxicological hazards and introduces no special nutritional or microbiological problems. An Expert Group constituted by WHO in 1994 once again reviewed the wholesomeness data available till then and validated the earlier conclusion of JECFI. The findings are published in the form of a monogram by WHO (WHO, 1994). In 1997 another Expert Group constituted by FAO/IAEA/WHO even affirmed the safety of doses higher than 10 kGy. The Codex Alimentarius Commission, which provides international standards for food has also published Codex General Standard for Irradiated Foods and Recommended International Code of Practice for Operation of Radiation Facilities for Treatment of Foods. 
Radiation processing can be carried out only in facilities licensed to do so. The license could be obtained after fulfilling the requirements of the Atomic Energy Regulatory Board (AERB), an independent regulatory body which looks in to all the safety aspects of a radiation processing plants. In fact a number of facilities for radiation processing of medical products are already in operation in India. 

In India, the Ministry of Health and Family Welfare, amended the Prevention of Food Adulteration Rules (1954) through a Gazette notification dated August 9, 1994, permitting irradiation of onion, potato and spices for internal marketing and consumption. In 1998 a number of other food items were permitted for radiation processing (Table-1a). Approval for additional items including fish and shrimp for shelf-life extension and pathogen control and disinfestation of dry fish and pulse products like besan is expected soon (Table-1b). 

 

Table–1a: Food items approved for radiation preservation by the Ministry of Health & Family Welfare under Prevention of Food Adulteration Rules, 1955.
Name of food Purpose Minimum Dose (kGy) Maximum Dose (kGy)
Onion  Sprout inhibition 0.03  0.09 
Potato  0.06  0.15 
Ginger 0.03  0.15 
Garlic  0.03  0.15 
Shallots (Small onion) 0.03 0.15 
Mango Disinfestation  (Quarantine) 0.25 0.75
Rice  Disinfestation 0.25  1.00 
Semolina (sooji, rawa), Wheat atta and maida  0.25 1.0
Raisin, figs and dried dates 0.25 0.75
Meat and meat products including chicken Shelf-life extension and pathogen control 2.5 4
Spices Microbial decontamination 6 14
Table–1b: Additional food items recommended by the Central Committee for Food Standards for approval 
Name of food Purpose Minimum Dose (kGy) Maximum Dose (kGy)
Pulses  Disinfestation 0.25  1.00 
Dried sea-foods 0.25  1.00 
Fresh sea-foods Shelf-life extension 1.00  3.00 
Frozen sea-foods Pathogen control 4.00  6.00 

 

APPLICATION OF RADIATION PROCESSING OF FOOD

Interest in the practical application of the process is emerging for many reasons. High food losses caused by insect infestation, microbial contamination and spoilage; mounting concern over food borne diseases, harmful residues of chemical fumigants and the impact of these chemicals on the environment, the stiff standards of quality and quarantine restrictions in international trade are some of the reasons. Though irradiation alone can not solve all the problems of food preservation, it can play an important role in reducing post-harvest losses and use of chemical fumigants. 
On the basis of radiation dose, applications of radiation can be classified into:

  • Low Dose Applications 
Sprout inhibition in bulbs and tubers 0.03 - 0.15 kGy
Delay of fruit ripening 0.25 - 0.75 kGy
Insect disinfestation including quarantine treatment and elimination of food borne parasites 0.25 - 1 kGy

 

Reduction of spoilage microbes to improve shelf-life of meat, poultry and seafoods under refrigeration 1.5 - 3 
kGy 
Elimination of pathogenic microbes in fresh and frozen meat, poultry and seafoods 3 - 7 
kGy 
Reducing number of microorganisms in spices to improve hygienic quality 10 kGy 
 

High Dose Applications 

Sterilization of packaged meat, poultry and their products which are shelf-stable without refrigeration
25 - 70 kGy
Sterilization of hospital diets 25 - 70 kGy

 

THE BENEFITS AND LIMITATIONS OF RADIATION PROCESSING OF FOOD
Benefits  Limitations 
Radiation processing is a cold process and therefore, unlike heat, it can be used on agricultural commodities without changing their fresh-like character Radiation processing is a need based technology and cannot be applied to all kinds of foods
Radiation processing dose not alter significantly nutritional value, flavour, texture and appearance of food Radiation processing cannot make a bad or spoiled food look goo
Radiation using Cobalt-60 cannot induce any radioactivity in food and does not leave any harmful or toxic radioactive residues on foods as is the case with chemical fumigantsd It cannot destroy already present pesticides and toxins in foods
Due to the highly penetrating nature of the radiation energy, it is a very effective method Amenability of a particular food commodity to radiation processing has to be tested in a laboratory
Prepackaged foods can be treated for hygienization and improving shelf-life Only those foods for which specific benefits are achieved by applying appropriate doses, and those duly permitted under the Prevention of Food Adulteration Act (PFA) Rules, 1955, can be processed by radiation.
The radiation processing facilities are environment friendly and are safe to workers and public around  

 

CONSUMER RESPONSES

Consumer acceptance is a major factor in commercialization of radiation processing technology. A number of surveys have been conducted nationally and internationally to study the response of consumers to radiation processed food. These surveys as well as limited market trials have demonstrated that consumers are receptive towards radiation processed food. A review on consumer attitudes and market response to food processed by radiation has shown that though consumers express concern about food processed by radiation, when presented with correct information, the acceptance is improved. To evaluate the public perception on radiation processed foods in India, a questionnaire was prepared. Response to tasting of irradiated foods conducted in Mumbai at several seminars organized by Professional bodies, and seminars for specific target groups like University Students, University and School teachers, officers and staff of Army Supply Depot, Mumbai and consumer and food industry groups have shown overwhelming positive response to eating snack items made from irradiated onions, potatoes and spices. The Defence Research and Development Organization (DRDO) have conducted `Ahar Utsavs' with irradiated foods among Defence personnel at several locations in the country with great success. In another study sensory evaluation of irradiated spices was carried out by housewives in Anushaktinagar (DAE staff quarters), college canteens and quantity cookery laboratory of SNDT Women's University, Mumbai. Higher percentage of subjects preferred stored irradiated to stored non-irradiated spices 


 

CONTROL AND REGULATIONS

Control of food processing in all types of facilities involves the use of accepted methods of measuring the absorbed radiation dose, the distribution of that dose in the product package, and of monitoring of the physical parameters of the process. Dosimetry for food irradiation is analogous to temperature monitoring in thermal processing, with dose meters being the analogs of thermocouples in that they are employed to provide an accurate measure of the rate of energy delivery, total energy delivered or absorbed and the over dose ratio. There are several types of dose meters, the most common ones being based on a chemical change that is linear within a practical dose range. Dosimetry is the keystone of the proper radiation processing. Careful dosimetry is required to ensure that a technologically useful dose has been applied, while maintaining the best possible dose uniformity ratio. Therefore, prior to commissioning of the plant, extensive dosimetric calibrations of the irradiator are carried out and followed during the processing by routine dosimetry. Because it is not possible to distinguish irradiated from non-irradiated products by sight, smell or taste, it is important that appropriate indicator devices which undergo radiation induced colour change be attached to each container/package, and that physical.


 

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. Past experience has shown enough market demand to sustain this activity.


 

KNOW-HOW AND TECHNOLOGY TRANSFER

Expertise and know-how for designing, fabrication and commissioning of irradiators is available in the country with the Department of Atomic Energy and Bhabha Atomic Research Centre. A prototype commercial demonstration irradiator with an initial throughput of 20 tons/day for treatment of spices has been commissioned in Vashi, under the management of Board of Radiation and Isotope Technology (BRIT), a constituent unit of the Department of Atomic Energy. The first prototype commercial demonstration irradiator for potatoes and onions (POTON) with a throughput of 10 tons/h is being set up in Lasalgaon, Nashik Dt., Maharashtra.
Two pilot-plant irradiation facilities, namely the Food Package Irradiator in Food Technology Division, Bhabha Atomic Research Centre and another at the Defence Laboratory, Jodhpur have been licenced for irradiating food items that have been cleared for domestic trade and consumption. It is proposed to use these irradiation facilities for treatment of limited commercial quantities for test marketing and consumer response surveys.


For further information on technology transfer write to:
Head 
Technology Transfer & Collaboration Division 
Bhabha Atomic Research Cenre 
Mumbai-400085


 

INTERNATIONAL STATUS

The Joint Expert Committee of the Food and Agricultural Organization (FAO), World Health Organization (WHO), and International Atomic Energy Agency (IAEA), in 1980 concluded that food processed by radiation up to a dose of 10 kGy is safe for human consumption and does not pose any special nutritional, microbiological or toxicological problems. These conclusions have also been reviewed and endorsed later by the similar Joint Expert groups set up from time to time and also by a number of scientific and technical associations and bodies Today over 30 countries world wide, including India, have approved the use of radiation processing of foods for over 100 food items and some of these countries are applying the technology on a limited commercial scale.


 

FREQUENTLY ASKED QUESTIONS

ANSWERS TO THESE COMMON QUESTIONS