食品辐照过去现在未来

Radiation Physics and Chemistry 63 (2002) 211–215 Food irradiationFpast, present and future J.F. Diehl* Wildbader Str.6, D 76228 Karlsruhe, Germany Abstract A review is presented of historical developments, the present situation, and expected future developments in the field of food irradiation. Acceptance of the process in different parts of the world is not uniform. In the USA and in some other countries where health authorities actively encourage the use of this technology, commercial application has greatly advanced in recent years. In contrast, progress in the European Union is still slow.r 2002 Published by Elsevier Science Ltd. Keywords: Radiation processing; Food preservation; Review 1. The past The early history of food irradiation is the history of radiation itself. Roentgen discovered X-rays in 1895, Becquerel recognized radioactivity in 1896. An outburst of research on the biological effects of ionizing radiation on living organisms followed these discoveries. Enter- prising inventors soon found practical applications of radiation. British Patent No. 1609 was issued in 1905 to J. Appleby and A. J. Banks for their invention ‘‘to bring about an improvement in the condition of foodstuffs’’ and in ‘‘their general keeping quality’’. They proposed the treatment of food, especially cereals, with alpha, beta or gamma rays from radium or other radioactive substances, stressing ‘‘the exceptionally marked advan- tage of an entire absence of the direct use or employment of chemical compounds’’. B. Schwartz of the US Department of Agriculture suggested the use of X-rays for inactivating trichinae in pork in 1921. A French patent was granted in 1930 to the German engineer O. W .ust for an invention to kill all bacteria in a packaged food by treatment with X-rays. None of these proposals led to a practical application, simply because the radiation sources available at that time, X-ray machines or radioactive isotopes, were not powerful enough to treat food in commercial quantities. However, technological developments during World War II produced equipment that could be adapted to improve radiation processing. Klystron tubes developed for radar were used to construct electron accelerators of very high power, and radioisotopes generated in nuclear reactors became available for large gamma ray sources. Early studies on food preservation using such radiation sources were described by Josephson (1983). Reports from the United States about successful experiments on irradiation of food stimulated similar efforts in other countries. By the mid- or late 1950s, national research programs on food irradiation were also underway in Belgium, Canada, France, The Federal Republic of Germany, Netherlands, Poland, the Soviet Union, and the United Kingdom. The first commercial use of food irradiation occurred in 1957 in Germany, when a spice manufacturer in Stuttgart began to improve the hygienic quality of its products by irradiat- ing them with electrons, using a van de Graaff generator. The machine had to be dismantled in 1959 when a new food law prohibited the treatment of food with ionizing radiation, and the company turned to fumigation with ethylene oxide instead. In Canada, irradiation of potatoes for inhibition of sprouting was allowed in 1960, and a cobalt-60 plant began irradiating potatoes in 1965. The facility was closed after only one season, when the company ran into financial difficulties. In spite of these setbacks, interest in food irradiation grew worldwide. At the first International Symposium *Fax: +49-721-453-726. E-mail address: j.f.diehl@t-online.de (J.F. Diehl). 0969-806X/02/$ - see front matter r 2002 Published by Elsevier Science Ltd. PII: S 0 9 6 9 - 8 0 6 X ( 0 1 ) 0 0 6 2 2 - 3 Dolly Dolly on Food Irradiation, representatives from 28 countries reviewed the progress made in national research programs (IAEA, 1966). Health authorities in these countries, however, still hesitated to grant permissions for marketing irradiated food. Unanswered questions about the safety of irradiated food for human consump- tion were recognized as the major obstacle to commer- cial utilization of the new process. Consequently, the International Project in the Field of Food Irradiation (IFIP) was created in 1970. The Project had the specific aim of carrying out a worldwide research program on the health safety of irradiated food. Under the sponsor- ship of FAO, IAEA and OECD, 19 countries joined their resources, with this number later growing to 24. Office and laboratory facilities for the project director and his staff were provided at the Federal Research Center for Nutrition in Karlsruhe, and IFIP was often designated as the ‘‘Karlsruhe Project’’. WHO became associated with IFIP as an advisor. The research program included long-term animal feeding studies, short-term screening tests, and the study of chemical changes in foodstuffs irradiated with a dose of up to 10 kGy (Diehl, 1995). The results obtained in the International Project and in national testing programs were repeatedly evaluated by the Joint FAO/IAEA/WHO Expert Committee on the Wholesomeness of Irradiated Food (JECFI). This Committee concluded in 1980 that the irradiation of any food commodity up to an overall average dose of 10 kGy presented no toxicological hazard and no special nutritional or microbiological problems (WHO, 1981). IFIP had successfully completed its task of examining the wholesomeness of food irradiated to a dose of up to 10 kGy and was terminated in 1982. Its results have been documented in more than 60 Technical Reports and in several books, such as (Elias and Cohen, 1983). National governments and international agencies that had participated in IFIP felt that the international platform for exchange of information on food irradia- tion provided by the Project since 1970 had been very useful and should be maintained. As a result of these considerations, the International Consultative Group on Food Irradiation (ICGFI) was created in 1983; it is now supported by 45 member countries. ICGFI provides publications on the safety of irradiated food, the effectiveness of food irradiation, commercialization of the process, legislative aspects, control of irradiation facilities, and acceptance of and information on food irradiation. The Web page /www.iaea.org/icgfiS pro- vides information on ICGFI activities and links to other food irradiation Web sites. On the basis of JECFI’s landmark decision of 1980, the Codex Alimentarius Commission adopted in 1983 a General Standard for Irradiated Foods and a Recom- mended International Code of Practice for the Opera- tion of Radiation Facilities. The World Health Organization encourages the use of the process, which it described as ‘‘a technique for preserving and improv- ing the safety of food’’ (WHO/FAO, 1988). WHO asked another group of experts to review and evaluate the results of scientific studies carried out after 1980, together with the older studies which had already been considered by previous international and national expert committees. The report of this expert group (WHO, 1994) fully confirmed the conclusions of the JECFI meeting of 1980. In 1997, an FAO/IAEA/WHO Study Group on High Dose Irradiation examined the results of safety studies carried out on food irradiated with doses higher than 10 kGy. Few foods tolerate doses above 10 kGy without loss of sensory quality. On the other hand, long-term animal feeding studies with foods irradiated with doses as high as 70 kGy have shown no treatment-related adverse health effects. The Study Group concluded that food irradiated to any dose appropriate to achieve the intended technological objective is both safe to consume and nutritionally adequate (WHO, 1999). Public opinion about food irradiation was generally positive during the growth period of nuclear technology in the 1950s and 1960s. With the advance of the anti- nuclear movement since the 1970s the climate of opinion changed and opposition to the practical use of food irradiation grew. Much more than other modern methods of food processing, food irradiation had to overcome barriers created by prejudice, misleading information, and highly restrictive legal and regulatory measures. 2. The present Aware of the opposition from some very vocal anti- irradiation activist groups and uncertain about the acceptance of irradiated commodities by consumers, the food industry has made little practical use of irradiation processing, although governments of 42 countries have approved the irradiation of various foods. For many years, spices and seasonings remained the only group of products irradiated worldwide on a significant scale. Irradiation of sizable quantities of frozen poultry, shrimps or frog legs remained limited to a few countries, such as France and Belgium. Concern about public health problems created by the presence of pathogenic microorganisms in food and the recognition of food irradiation as an effective tool to combat these problems, have recently helped to overcome the barriers. The quantity of spices and dried seasonings irradiated to improve their hygienic status has grown from about 8000 t in 1987 to over 80,000 t in 1998 (Diehl, 2000). According to estimates provided by the Food and Environmental Protection Section of FAO/IAEA, Vien- na, the quantity of food processed by irradiation J.F. Diehl / Radiation Physics and Chemistry 63 (2002) 211–215212 worldwide increased from about 200,000 t in 1997 to 257,000 t in 1999. Especially the food industry in the United States of America is now actively pursuing the possibilities of irradiating products other than spices. In August 1999, the Food Irradiation Coalition, an alliance of food industry trade associations, health organiza- tions, academic and consumer groups, has asked the US Food and Drug Administration (FDA) to allow irradiation of ready-to-eat meat and poultry products and fruit and vegetable products for the purpose of eliminating illness-causing microorganisms. The Coali- tion has the support of prominent public health experts who have emphasized the health benefits of food irradiation and have lamented the slowness in the adoption of the new technology (Lee, 1994; Crawford and Ruff, 1996; Lutter, 1999). In the United States, irradiation of meat and meat products requires prior approval not only by FDA, but also by the US Department of Agriculture’s Food Safety and Inspection Service (USDA/FSIS). FDA approved irradiation of refrigerated or frozen raw meat and meat products for control of foodborne pathogens in 1997, FSIS’s separate approval became effective in February 2000. The first commercial packages of irradiated beef reached the retail consumer market in May 2000. The frozen beef patties (hamburgers) were electron irradiated at Sioux City, Iowa, by SureBeam Corporation; they were marketed in five states by the end of May 2000 (Mermelstein, 2000) and in 18 states by February 2001 (Mermelstein, 2001). The Iowa facility is capable of processing about 100,000 t of hamburger meat per year. Another company, Ion Beam Applications, irradiates spices herbs and feeds in eight plants located in California, Illinois, New Jersey, North Carolina, and Texas. A cobalt-60 source instead of an electron accelerator is being used by Food Technology Service, Inc. (FTS), Mulberry, Florida, the first irradiation company in the United States dedicated specifically to the food industry, to process frozen poultry and a number of other products. The plant began operation in 1994, then under the name of Vindicator, Inc. Since August 2000, FTS is also irradiating frozen beef patties and fresh ground beef. Sterris Isomedix, also using cobalt-60 sources, has three irradiation plants in New Jersey and Illinois. Other commercial irradiators dedicated to food irradiation are under construction in the USA (Arkan- sas, New Jersey, New York), and several more are being planned. Another promising application of radiation proces- sing is irradiation of papayas and other exotic fruits (rambutan, lychee, star fruit, atemoya) in Hawaii for shipment to the US mainland. Until recently, quarantine regulations to prevent the spreading of fruit flies from Hawaii to orchards in California have severely restricted the export of tree-ripened Hawaiian papaya and other tropical fruits to US mainland consumers. The fruits had to be steam-heated for several hours in order to kill fruit flies in the interior of the fruit. This was only possible with fruits picked green. In contrast, disinfesta- tion by irradiation (IAEA, 1992) can be carried out on tree-ripened fruit, enabling Hawaiian exporters to offer products of much higher quality. The first commercial X-ray irradiator for food irradiation started operating in July 2000 in Hilo, Hawaii. This development is also of great interest to fruit growers and exporters in Central and South America. The Interim Commission on Phytosanitary Measures of the International Plant Protection Convention has considered irradiation as a phytosanitary measure at its session in Rome, 2–6 April 2001. Irradiation of fruit for quarantine purposes may eventually facilitate and stimulate fruit trade worldwide. In other countries, new commercial irradiators avail- able for food irradiation have been recently commis- sioned in Brazil, China, India, Republic of Korea, Mexico, and Thailand. In Europe, some countries were early supporters of industrial food irradiation, particu- larly Netherlands and France. In contrast, German governments, while supporting research in this field, did everythingFunder pressure from anti-nuclear groupsFto keep irradiated food from reaching the market. Greatly differing national legislations on food irradiation were the result. One of the important tasks of the bodies ruling the European Union (EU) is the harmonization of food laws in the member countries. A first draft of a European Directive on food irradiation was proposed by the European Council in 1988. It contained a ‘‘positive list’’ of nine commodities or commodity groups for which irradiation was to be permitted. After more then 10 yr of debate in the European Parliament in Strasbourg and in various agencies in Brussels a new European set of rules on food irradiation was finally adopted and published in the EU’s Official Gazette on 13th March 1999. In the course of the legislative process the ‘‘positive list’’ of permitted commodities has been whittled down from the original nine to a single group: dried aromatic herbs, spices and vegetable seasonings. Any food irradiated as such or containing irradiated food ingredients has to be labelled ‘‘irradiated’’ or ‘‘treated with ionizing radia- tion’’, regardless of how small the proportion of irradiated ingredients in the product may be. This is bound to cause technical difficulties. Spices are often purchased as mixtures, and components may sometimes be irradiated, and sometimes not. The cost of changing labels accordingly, would be high. The present positive list is considered as provisional, and EU member countries that have national permissions for irradiation of other products, such as France for frozen poultry meat, and Belgium, France, and the Netherlands for frozen shrimps, can request to get these items added to the final positive list. But this will not be easily achieved. J.F. Diehl / Radiation Physics and Chemistry 63 (2002) 211–215 213 Dolly Any addition to the list requires approval by the European Parliament. The way in which food irradia- tion was systematically downgraded and misrepresented in the European Parliament has been documented (Diehl et al., 1991). There is as yet no indication that the influence of anti-irradiation forces in that Parliament has decreased. Under these circumstances, the status of food irradiation in the EU is not very encouraging. Space does not permit consideration of the situation in the many other countries where food irradiation is practiced to some extent. An overview of recent developments in the application of this technology has just become available (Loaharanu and Thomas, 2001). 3. The future What is the outlook for research in the field of food irradiation? Research programs in the 1990s emphasized improvement of methods of detection of irradiated foods. Whereas some twenty years ago it was not possible on the basis of chemical analysis to differentiate between irradiated and nonirradiated samples of a foodstuff, a number of reliable analytical methods are now available (Delinc!ee, 1998). Another big push in this area is unlikely. Of course there will always be research on irradiated food, just as on cooked or dried or frozen food. There will be more studies on the radiation resistance of various species of microorganisms and on factors that influence it; on chemical reactions induced by irradiation in different media; on losses of this or that vitamin under varying conditions of irradiation and storage; on combination methods (radiation plus heat, water activity, pH, packaging atmosphere, etc.); on the suitability of various packaging materials for irradiated foods; on the effect of irradiation conditions on the sensory quality of foodstuffs; on the minimal radiation dose required to sterilize, inactivate or kill specific insects, parasitic helminths or protozoa, and so on. But a resumption of the concerted efforts that stimulated so much research in this field in the 1960s to 1980s is unlikely. The fact that the last International Symposium on Food Irradiation was held in 1985 (IAEA, 1985) may be taken as an indication of a decreasing importance assigned to research in this field. To what extent will food irradiation be practiced? All indications are that radiation processing of food will grow, but the pace will be very different in various parts of the world. In the United States, where the health authorities actively encourage the use of this technology, the presently rapid growth of progress is likely to continue. Other countries of the Americas will probably follow the trend set in the United States. Progress in the European Union is decidedly slower. With Green Party politicians in the European Parliament, outspoken opponents to the use of any nuclear technology, the policy of delay and obstruction that has prevailed during the 1980s and 1990s is likely to continue. Some countries in other continents take positions close to that of the United States, some others are as reluctant as the European Union. To what extent will new international activities influence progress in this field? The International Atomic Energy Agency in Vienna, which has supported research and development in this field for many decades, is subject to budget restrictions. Its Food Preservation Section has recently been merged with the Agrochem- icals Section to form a new Food and Environmental Protection Section, with less budget and less staff available for food irradiation activities. The mandate of the International Consultative Group on Food Irradiation (ICGFI) was recently extended for 3 yr, until May 2002. Representatives of some member countries have expressed the opinion that food irradia- tion is now an established industrial technology that can stand on its own feet. The future of ICGFI is therefore somewhat uncertain. A positive sign on the international scene is the revision of the General Standard for Irradiated Foods and the Recommended International Code of Practice for Radiation Processing initiated by the Codex Alimentarius Commission. At its 33rd session in March 2001, the Codex Committee on Food Additives and Contaminants has moved the revision of the General Standard to Step 5 of the Codex procedure. Recognizing the recommendations of international groups of experts that have become available since the present General Standard was adopted in 1983, this revision of the General Standard removes the 10 kGy upper dose limit. The comp