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January 1, 1998
First published in Food Technology Magazine January 1998. 52[1]: 56-62. (Download PDF version)
The Food and Drug Administration's (FDA) approval of irradiation for red meats in December 1997 ended a long chapter in the tumultuous history of an important food safety and preservation technology. Federal acceptance validates what food scientists have long known: that appropriate absorbed doses of radiation effectively kill disease-causing bacteria and delay food spoilage. When irradiated ground beef becomes available, consumers once again may enjoy their hamburgers rare or medium rare. Low doses of radiation can kill at least 99.9% of Salmonella in poultry and an even higher percentage of Escherichia coli O157:H7 in ground beef.
This summary briefly addresses the remaining questions about food irradiation. In addition, it provides a useful summary of the regulatory history and the current state of scientific knowledge of the technology as applied to food. Federal regulators, food scientists, food processors, and consumers will write the next chapter in the story of irradiation. New challenges awaiting resolution include safely and successfully implementing irradiation in the meat and poultry processing industries; maintaining the quality of raw, irradiated meats; developing packaging suitable for irradiation; developing methods to detect irradiated foods; and educating the public about the wholesomeness of foods made safer by irradiation.
Although irradiation of medical devices and disposables has a long history of use (Derr, 1993), irradiated foods were not produced commercially in the United States until 1992. Radiation is cleared for use on at least one food product in 35 countries, and irradiated foods are commercially available in 28 developing as well as developed countries (IAEA, 1995; Loaharanu, 1996). Spices are the most commonly irradiated food. Other commercially-available irradiated foods include a variety of fruits and vegetables, rice, potatoes, onions, sausage, and dried fish (in Bangladesh only). At least one irradiated muscle food (meat, poultry, and seafood) is cleared for use in 18 countries, including Chile, France, and the Netherlands.
The number of retail outlets offering irradiated foods and the amount of irradiated foods commercially available in the United States has grown slowly. Only four retail stores in the United States continuously offer irradiated foods. Use of irradiated foods has grown slightly faster in the food service sector, primarily in hospitals for reducing the potential for cross contamination in food preparation and for immune-compromised patients.
When molecules absorb ionizing energy, they become reactive and form ions or free radicals that react to form stable radiolytic products (Woods and Pikaev, 1994). The Council for Agricultural Science and Technology (CAST, 1989) estimated that a dose of 1 kGy would break fewer than 10 chemical bonds for every ten million bonds present, an extremely small percentage. Cooking, or applying infrared radiation to foods, produces similar changes in chemical bonds.
Even though an extremely small percentage of chemical bonds are broken when a food is irradiated, the effect can be dramatic. For example, breaking bonds in the deoxyribose nucleic acid (DNA) results in the loss of a cell's ability to replireplicate. A relatively small change in the DNA of a bacterial cell can destroy the cell. The cellular destruction caused by disruption of the genetic material in a living cell is the principal effect of radiation on food (Murano, 1995a), enabling destruction of insects, inactivation of parasites, delaying of ripening, and prevention of sprouting. Ionizing radiation cannot make food radioactive. The physical laws that govern the nature of chemical reactions and the stability of chemical substances are the same whether the enhanced molecular reactivity created by heat energy is supplied by infrared radiation, microwaves, ionizing radiation, or other sources (CAST, 1986). The radiolytic products that form when food is irradiated are generally the same as those that are formed when food is cooked. Investigators developing methods for detecting irradiated foods have identified alkylcyclobutones in some irradiated foods that were not detected in unirradiated samples. These substances may serve as markers for irradiated foods. Despite concerns expressed by those who decry the use of radiation, no unique radiolytic products of toxicological significance have been found in irradiated foods (Crawford and Ruff, 1996).
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Table 1 Applications of Ionizing Radiation Accepted in the U.S. by the Food and Drug Administration.
The issue of toxicological safety raises the questions: (1) Is there evidence of adverse toxicological effects that can be attributed to toxic substances produced by irradiating the food? (2) What should be tested? (3) What tests provide useful information? The questions are difficult to address because radiation leads to the absorption of ionizing energy rather than the addition of a substance. The toxicological safety of food additives has traditionally been assessed by animal feeding studies and involves determining the highest dose of a substance that causes no toxicological effects, and the application of safety factors to account for individual variability and uncertainty in extrapolating from animals to humans (Pauli and Tarantino, 1995).
To assess the changes caused in foods by irradiation and recommend toxicological testing requirements for assessing their safety, the FDA formed the Bureau of Foods Irradiated Food Committee (BFIFC). Because no evidence of toxicity attributable to irradiation of food was found, the committee recommended that foods irradiated at doses less than 1 kGy, or foods representing only a very small fraction of the diet, should be exempt from requirements for toxicological testing. FDA then organized a task group to assess animal feeding and mutagenicity studies. The group concluded that toxic effects are not expected from foods irradiated at doses below 1 kGy and concurred with the recommendation of the BFIFC. Because available data were not adequate to evaluate the safety of irradiation of all foods at doses greater than or equal to 1 kGy, the task group also recommended that the agency consider authorizations of the process on a case-by-case basis for foods that are consumed in significant amounts or that are irradiated at higher doses. Hence, the poultry petition that was cleared by FDA in 1990 (9 CFR Part 381) was considered separately because the petition requested radiation dose levels greater than 1 kGy.
With the red meat petition, however, the concept of chemi-generic clearance was used. This concept is that radiation chemistry of the constituent components (e.g., water, protein, lipid, carbohydrates) among a food group produces common and predictable stable endproducts. Muscle foods, for example, have similar macronutrient composition and, therefore, are expected to yield similar radiolytic products. The database of the toxicological studies completed for the poultry petition can thus be used to address toxicological questions about different meat species and fish. For foods to be irradiated above 1 kGy, FDA's principal interest is with the conditions for food irradiation (temperature, packaging atmosphere, dose range) and their impact on microbiological safety and nutritional adequacy.
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Table 2 Information Required by the U.S. Food and Drug Administration To Establish the Safety of Irradiated Food
The issue of microbiological safety of irradiated foods raises many questions; the two most important are: (1) Can irradiation mutate microorganisms, producing more virulent pathogens? (2) Will irradiation reduce the numbers of spoilage microorganisms, allowing pathogens to grow undetected without competition? FDA does not consider radiation- induced mutation a concern with respect to increased virulence or heat resistance since there is no evidence for such effects. In fact, radiation is much more likely to reduce the virulence of any surviving pathogens (Farkas, 1989). FDA requires evidence that radiation, under realistic conditions, achieves the intended microbiological effect without allowing Clostridium botulinum to grow and produce toxin undetected.
The two most important questions of nutritional adequacy of irradiated foods are: (1) Does irradiation result in a significant loss of any nutrient in the food under the proposed conditions of use? (2) Is the food proposed for irradiation an important dietary source of the affected nutrient? Many food processes, like cooking, alter nutrient content much more than irradiation. Trace elements and minerals are not affected by irradiation. Macronutrients such as protein, carbohydrates, and fats are not significantly affected by doses up to 10 kGy. Even with sterilization doses of 50 kGy, macronutrient losses are small and nonspecific (Diehl, 1995; WHO, 1994).
Some vitamins, however, are sensitive to radiation. The amount of vitamin loss due to food irradiation is affected by several factors, including dose, temperature, presence of oxygen, and food type. Generally, radiation at low temperatures in the absence of oxygen reduces any vitamin loss in foods, and storage of irradiated foods in sealed packages at low temperatures also helps prevent future vitamin loss (WHO, 1994). Not all vitamins have the same sensitivity to irradiation. For water soluble vitamins, the order of sensitivity is generally: thiamin > ascorbic acid > pyridoxine > riboflavin > folic acid > cobalamin > nicotinic acid. For fat soluble vitamins, the order of sensitivity is generally: vitamin E > carotene > vitamin A > vitamin K > vitamin D (WHO, 1994).
FDA requires that the affected vitamin(s) in the irradiated food are not significant in the overall diet. The nutritional significance of vitamin loss due to irradiation depends on the level of loss and the proportion of the irradiated food in the diet. It is doubtful that any vitamin deficiency would develop from consuming irradiated foods. For example, pork is a major source of thiamin, the most radiation sensitive water-soluble vitamin, but only 2.3% of thiamin in American's diets would be lost if all the pork in the United States were to be irradiated (CAST, 1996).
The most recent World Health Organization (WHO) review of the safety and nutritional adequacy of irradiated foods concluded that food irradiation: (1) will not lead to toxicological changes in the composition of food that would have an adverse effect on human health; (2) will not increase microbiological risk; and (3) will not lead to nutrient losses that would have an adverse effect on the nutritional status of people (WHO, 1994). Furthermore, a meeting of the Food and Agriculture Organization of the United Nations, International Atomic Energy Agency, and the World Health Organization (WHO) concluded on the basis of knowledge derived from over 50 years of research that irradiated foods are safe and wholesome at any radiation dose (WHO, 1997).
As with cooking and thermal processing, higher radiation doses kill greater numbers of bacteria. The D values (decimal reduction, or dose required to destroy 90% of the microorganisms present) of several pathogenic bacteria that may be associated with raw meat and poultry are shown in Table 3. Salmonella is the most resistant nonspore forming pathogen, with a D value of about 0.6 kGy. The radiation doses approved for poultry, 1.5–3.0 kGy, would destroy about 99.9% (3 logs) to 99.999% (5 logs) of Salmonella. Except for spores of Clostridium botulinum, all other pathogenic bacteria listed in Table 3 would be controlled within this dose range. A minimum dose of 1.5 kGy would destroy at least 6 logs of E. coli O157:H7, which has a D value of about 0.24 kGy. Irradiation, therefore, would be extremely effective at eliminating this pathogen, declared an adulterant in ground beef in 1994. The parasites Toxoplasma gondii and Trichinella sprialis are inactivated at doses of 0.25 kGy (Dubey et al., 1986) and 0.3 kGy (Brake et al., 1985), respectively.
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Table 3 D values of some important foodborne pathogens
Although the primary objective of irradiation of muscle foods is destruction of pathogenic bacteria, substantial reduction of spoilage microorganisms also occurs. Niemand et al. (1983) reported that levels of aerobic and anaerobic bacteria were reduced by over four logs and almost five logs, respectively, in chilled ground beef irradiated at doses to 2.5 kGy. Shelf life of the ground beef stored at 4°C was extended by nine days, before counts reached seven logs. The refrigerated shelf-life of vacuum-packaged beef sirloin cuts irradiated to 2 kGy more than doubled, from about four weeks for non-irradiated product stored at 0°C to 10 weeks for irradiated product stored at 4°C (Niemand et al., 1981). Lefebvre et al. (1992) reported a three log reduction in psychrotrophic aerobic bacteria in ground beef irradiated at 2.5 kGy. The irradiated ground beef had a shelf-life of ten days before counts reached seven logs compared with the non-irradiated control which lasted only one day.
Lambert et al. (1992) found that pork loin slices packaged under nitrogen and irradiated to 1 kGy had a 26-day shelf-life (21 days more than the control) stored at 5°C. Thayer et al. (1993) found that uninoculated ground pork, irradiated at 1.9 kGy, had no surviving bacteria when stored at 2°C for up to 35 days.
The predominant food spoilage organisms are Gram-negative psychrotrophic microorganisms that are very susceptible to radiation (Monk et al., 1995). Several researchers have shown that irradiation of food at doses of at least 1 kGy virtually eliminate Gramnegative microorganisms, but has a much smaller effect on Gram-positive lactic acid-producing microorganisms (Dempster, 1985; Ehioba et al., 1988; Lambert et al., 1992; Mattison et al., 1986; Niemand et al., 1983; Thayer et al., 1993). Pseudomonas species and Enterobacteriaceae, common spoilage bacteria, are easily eliminated even with low doses of radiation. However, in all of these studies at doses in the range of 1–5 kGy, Gram-positive microorganisms survived and caused spoilage after prolonged refrigerated storage.
Irradiation may affect the quality of meat by processes other than those attributable to microorganisms. Radiation dose, dose rate, temperature and atmosphere during irradiation, and temperature and atmosphere during storage can all affect the outcome of specific foods (Thayer, 1990). Radiolytic products can cause oxidation of myoglobin and fat, leading to discoloration and rancidity or other off-odor or off-flavor compounds (Murano, 1995b). Ozone, a strong oxidizer, is produced from oxygen during food irradiation and may oxidize myoglobin, causing a bleaching discoloration.
Some scientists have observed that irradiated raw meat developed an off-odor compared with the non-irradiated control (Lefebvre et al., 1994; Lynch et al., 1991). Sudarmadji and Urbain (1972) reported that the threshold dose for irradiation odor ranged from 1.5 kGy for turkey to 6.25 kGy for lamb. Niemand et al. (1981) reported that an irradiation odor was detected but not objectionable in raw beef irradiated at low dose. Cooking appears to reduce or eliminate any irradiation- induced odor (Kropf et al., 1995; Luchsinger et al., 1996). Odor resulting from irradiation may thus be important only in raw meat. Further investigation would enable full characterization of irradiation-induced odor and better understanding of the conditions that affect its development.
Irradiation can also cause some color changes in meat, that are greatly influenced by the packaging environment. For example, irradiated vacuum packaged meat can develop a fairly stable brighter red or pink color in pork, beef, and turkey breasts (Lebepe et al., 1990; Lynch et al., 1991; Niemand et al., 1983). In the presence of oxygen, however, irradiation can cause discoloration. Grant and Patterson (1991) observed discoloration in pork irradiated in the presence of oxygen. Irradiation of frozen grass prawns at 10 kGy reduced levels of polyunsaturated fatty acids (C20:5 and C22:6) by 25–32%, possibly due to oxidation and decomposition of lipids into volatile compounds (Hau et al., 1992). The threshold dose for development of irradiation flavor in the frozen grass prawns was 4.5 kGy.
The extent of chemical changes that occur in the frozen state is less than that in non-frozen food due to decreased mobility of free radicals. With less mobility in the frozen state, free radicals tend to recombine to form the original substances rather than diffuse through the food and react with other food components (Taub et al., 1979). Irradiating foods at appropriate doses and under certain conditions, such as in a reduced oxygen or oxygen-free atmosphere, packaging, and the frozen state, can minimize or avoid the development of objectionable off-odors and flavors. Irradiated meat will be successful in the market place only if consumers are satisfied with its sensory quality.
To obtain the full benefit from the potential to reduce levels of microorganisms, eliminate pathogens, and prevent cross-contamination, muscle foods should be packaged before irradiation. Irradiation of packaging film may result in evolution of gases, such as hydrogen, and production of low-molecular weight hydrocarbons and halogenated polymers (Kilcast, 1990). The impact of irradiation on the packaging material itself must, therefore, be considered (Lee et al., 1996).
Materials used to package foods before irradiation must be accepted for such use by the FDA. Acceptable materials are listed in 21 CFR 179.45. Any coextruded or laminate multicomponent films, commonly used for packaging non-irradiated muscle foods, must be accepted by FDA before use in food irradiation.
At radiation doses accepted for food, only low-molecular weight polymers and gases have the potential for migrating into the product and influencing product quality. Taint-transfer problems, for example, have been observed when the commonly used fresh meat overwrap polyvinylchloride (PVC) was irradiated at 3.9 kGy (Kilcast, 1990). PVC, however, is not accepted by FDA for use in food irradiation. Antioxidants used in packaging films may also be significantly degraded, although migration of antioxidants into the food product has not been observed (Buchalla et al., 1993).
The suitability for food irradiation of new types of polymeric packaging material, including co-extrudates and multilayer laminates requires further investigation. In addition, additives, adhesives, and printing materials should also be screened (Kilcast, 1990). Determination of the threshold level of migration of film components, resins, and additives is required to expand the availability of FDA-approved polymeric films. With FDA approval of individual film components, film manufacturers would be able to develop film structures that would have defacto FDA approval without having to petition for approval of each new film structure.
Because there are no major chemical, physical, or sensory changes in irradiated foods, detection methods must focus on minute changes. Glidewell et al. (1993) prepared a comprehensive review of over 200 references relating to detection methods for irradiated foods. Generally, detection methods focus on chemical, physical, histological, morphological, and biological changes in the foods.
Lipids and DNA are particularly sensitive to ionizing radiation. Crone et al. (1992) detected 2-alkyl-cyclobutone, a cyclic compound formed from fatty acids in irradiated but not cooked lipidcontaining foods. An interlaboratory comparison of the cyclobutone method correctly identified, with no false positives, 99% of 134 samples (ADMIT, 1994). Detection of hydrocarbons from irradiated lipid-rich foods is also a promising detection method. In an interlaboratory comparison of irradiated and non-irradiated chicken, 93% of 239 samples were correctly identified. False negative results occurred only in samples irradiated at 0.5 kGy (ADMIT, 1994).
DNA base damage, single-strand and double-strand DNA breaks, and crosslinking between bases are the main effects of irradiation. Detection and quantification of these DNA changes hold some promise for determining that an uncooked food has been irradiated. Further development is needed to distinguish irradiation-induced DNA changes from those caused by other processing treatments (Stevenson, 1992).
Techniques for detecting measurable changes in physical properties of foods, such as cell membrane damage, hold potential. Detection methods for membrane damage include measurement of electrical impedance, viscosity, electric potential, electron spin resonance, and thermal and near-infrared analysis (WHO, 1994). Hayashi (1988) reported that electrical impedance may be effective in determining irradiation of potatoes. Electron spin resonance appears effective for detecting irradiated bone-containing food and possibly shellfish (Derosiers, 1989; Gray and Stevenson, 1989).
Thermoluminescence (TL) has been successfully used to identify over 20 irradiated spices (Heide and Bögl, 1990). Sanderson (1991) demonstrated that contaminated minerals in spices are responsible for their TL. The use of TL for field crops, such as vegetables, fruits, and grains would be possible, as they all contain some minerals (WHO, 1994).
Changes in cell structures due to irradiation may be measurable by histological and morphological methods. Measuring the percentage germination of viable seed in fruits and the microscopic changes in cell structure could indicate whether the food has been irradiated. Because such measurements can take from days to weeks to complete, the methods may be impractical.
Determining the ratio of viable to total (viable and dead) bacteria on a food using aerobic plate count and the direct epifluorescent filter technique could determine if the food has been irradiated (WHO, 1994). The technique becomes limited, however, if the initial contamination before irradiation is very low, radiation dose is very low, or the food was irradiated to delay ripening rather than to pasteurize. Differences in radiation sensitivity of Gram-negative bacteria and Gram-positive bacteria may be useful. If a large number of Gram-positive bacteria, which are not as sensitive to irradiation as Gram-negative bacteria, are found on a food concurrent with a very low number of Gram-negative bacteria, it is likely that the food has been irradiated. The assumption would have to be made, however, that the initial bacterial contamination on the food is a normal mix of Gram-negative and Gram-positive microorganisms.
In summary, there are several promising techniques to screen and detect a few irradiated foods. No one technique is likely to be applicable to all food materials. Methods likely to become internationally accepted protocols are hydrocarbon and cyclobutone for lipid-containing foods, electron spin resonance for bone-containing food, and thermoluminescence for foods containing silicate minerals. Considerably more collaborative work is necessary to develop universally accepted methods for detecting irradiated foods of all types.
A survey conducted by Resurreccion et al. (1995) showed that 72% of responders were aware of irradiation, but 87.5% of those did not know much about it. Survey participants expressed less concern about food irradiation than food additives, pesticide residues, animal drug residues, growth hormones, and bacteria. Risks to workers and the environment were among the top concerns expressed about irradiation. Further, Resurreccion et al. (1995) found that 45% of the consumers would buy irradiated food, 19% would not buy it, and the others were undecided. Bruhn (1995) reported that the number of consumers concerned about the safety of irradiated food decreased from 42% to 35% in the last six years and was less than the number concerned about pesticide residues, microbiological contamination, and other food-related issues. Shin et al. (1992) reported that consumers were willing to pay up to $0.81 per meal, more than 10- fold greater than the cost of irradiating food (Morrison, 1989), to avoid foodborne illness.
Anellis, A., Berkowitz, D., and Kemper, D. 1977. Comparative radiation death kinetics of Clostridium botulinum spores at low-temperature gamma irradiation. J. Food Protect. 40: 313-316.
Brake, R.J., Jurrell, K.D., Ray, E.E., Thomas, J.D., Muggenburg, B.A., and Sivinski, J.S. 1985. Destruction of Trichinella spiralis by low-dose irradiation of infected pork. J. Food Safety 7: 127-143.
Bruhn, C. 1995. Consumer attitudes and market response to irradiated food. J. Food Protect. 58: 175- 181.
Buchalla, R., Schüttler, C., and Bögl, K.W. 1993. Effects of ionizing radiation plastic food packaging materials: A review. J. Food Protect. 56: 998-1005.
CAST. 1986. Ionizing energy in food processing and pest control: I. Wholesomeness of food treated with ionizing energy. Task Force Report No. 109. Council for Agricultural Science and Technology, Ames, Iowa.
CAST. 1989. Ionizing energy in food processing and pest control: II. Applications. Task Force Report No. 115. Council for Agricultural Science and Technology, Ames, Iowa.
CAST. 1996. Radiation pasteurization of food. Issue paper, No. 7. Council for Agricultural Science and Technology, Ames, Iowa.
Clavero, M.R.S., Monk, J.D., Beuchat, L.R., Doyle, M.P., and Brackett, R.E. 1994. Inactivation of Escherichia coli 0157:H7, Salmonellae, and Campylobacter jejuni in raw ground beef by gamma irradiation. Appl. Environ. Microbiol. 60: 2069-2075.
Crawford, L.M. and Ruff, E.H. 1996. A review of the safety of cold pasteurization through irradiation. Food Control 7(2): 87-97.
Crone, A.V.J., Hamilton, J.T.G., and Stevenson, M.H. 1992. Effects of storage and cooking on the dose response of 2-dodecylcyclobutanone, a potential marker for irradiated chicken. J. Sci. Food Agric. 58: 249- 252.
Dempster, J F. 1985. Radiation preservation of meat and meat products: A review. Meat Sci. 12: 61-89.
Derosiers, M.F. 1989. Gamma-irradiated seafoods: Identification and dosimetry by electron paramagnetic resonance spectroscopy. Rad. Phys. Chem. 37: 96-101.
Derr, D.D. 1993. International regulatory status and harmonization of food irradiation. J. Food Protect. 56(10): 882-886.
Diehl, J.F. 1995. Nutritional adequacy of irradiated foods. In "Safety of Irradiated Foods." 2nd Ed., Marcel Dekker, Inc., New York, NY.
Dubey, J.P., Brake, R.J., Murrell, K.D., and Fayer, R. 1986. Effect of irradiation on the viability of Toxoplasma gondii cysts in tissues of mice and pig. Am. J. Vet. Res. 47: 518-522.
Ehioba, R.M., Kraft, A.A., Molins, R.A., Walker, H.W., Olson, D.G., Subbaraman, G., and Skowronski, R.P. 1988. A research note: Identification of microbial isolates from vacuum-packaged ground pork irradiated at 1 kGy. J. Food Sci. 53: 278-279, 281.
El-Zawahry, Y.A. and Rowley, D.B. 1979. Radiation resistance and injury of Yersinia enterocolitica. Appl. Environ. Microbiol. 37: 50-54.
FDA. 1986. Irradiation in the production, processing and handling of food. Food and Drug Administration. Fed. Reg. 51(75): 13376-13399.
Farkas, J. 1989. Microbiological safety of irradiated foods - Review. Intl. J. Food Microbiol. 9: 1-15.
Glidewell, S.M., Deighton, N., Goodman, B.A., and Hillman, J.R. 1993. Detection of irradiated food: A review. J. Sci. Food Agric. 61: 281-300.
Grant, I.R. and Patterson, M.F. 1991. Effect of irradiation and modified atmosphere packaging on the microbiological and sensory quality of pork stored at refrigeration temperatures. Intl. J. Food Sci. Technol. 26: 507- 519.
Gray, R. and Stevenson, M.H. 1989. The effect of postirradiation cooking on ESR signal in irradiated chicken drumsticks. Intl. J. Food Sci. Technol. 24: 447-450.
Hau, L.-B., Liew, M.-H., and Yeh, L.-T. 1992. Preservation of grass prawns by ionizing radiation. J. Food Protect. 55(3): 198-202.
Hayashi, T. 1988. Identification of irradiated potatoes by impedemetric methods. In "Health Impact, Identification and Dosimetry of Irradiated Foods." Report of a WHO working group. Neuherberg, Institut für Strahlenhygiene des Bunddesgesundheitsamtes, Germany.
Heide, L. and Bögl, K.W. 1990. Detection methods for irradiated food - luminescence and viscosity measurements. Intl. J. Rad. Biol. 57: 201-219.
Huhtanen, C.N., Jenkins, R.K., and Thayer, D.W. 1989. Gamma radiation sensitivity of Listeria monocytogenes. J. Food Protect. 52: 610-613.
IAEA. 1995. Food Irradiation Newsletter. Supplement. Vol. 19(2), Intl. Atomic Energy Agency, Vienna, Austria. IFT. 1983. Radiation preservation of foods. A Scientific Status Summary by the Institute of Food Technologists' Expert Panel on Food Safety and Nutrition, Chicago, Ill. Food Technol. 37(2): 55-61.
Kilcast, D. 1990. Irradiation of packaged food. In "Food Irradiation and the Chemist," ed. D.E. Johnson and M.H. Stevenson. The Royal Society of Chemistry, United Kingdom, Special Pub. No. 86.
Kropf, D.H., Hunt, M.C., Kastner, C.L., and Luchsinger, S.E. 1995. Palatability, color, and shelf-life of low-dose irradiated beef. Proceedings of the 1995 International Congress of Meat Science and Technology, San Antonio, Texas.
Lambert, A.D., Smith, J.P., and Dodds, K.L. 1992. Physical, chemical and sensory changes in irradiated fresh pork packaged in modified atmosphere. J. Food Sci. 57: 1294-1299.
Lebepe, N., Molins, R.A., Charoen, S.P., Iv, H.F., and Showronski, R.P. 1990. Changes in microflora and other characteristics of vacuum-packaged pork loins irradiated at 3.0 kGy. J. Food Sci. 55: 918-924.
Lee, M., Sebranek, J.G., Olson, D.G., and Dickson, J.S. 1996. Irradiation and packaging of fresh meat and poultry. J. Food Protect. 59: 62-72.
Lefebvre, N., Thibault, C., and Charbonneau, R. 1992. Improvement of shelf-life and wholesomeness of ground beef by irradiation. 1. Microbial aspects. Meat Sci. 32: 203-213.
Lefebvre, N., Thibault, C., Charbonneau, R., and Piette, J.-P.G. 1994. Improvement of shelf-life and wholesomeness of ground beef by irradiation. 2. Chemical analysis and sensory evaluation. Meat Sci. 36: 371- 380.
Loaharanu, P. 1996. Historical developments on food irradiation. Presented at Control of Foodborne Illness: Radiation and Other Non-thermal Treatments, sponsored by the National Center for Food Safety and Technology and the Institute of Food Technologists in cooperation with the International Consultative Group on Food Irradiation, Rosemont, Ill., May 13-15.
Luchsinger, S.E., Kropf, D.H., Garciá Zepeda, C.M., Chambers IV, E., Hollingsworth, M.E., Hunt, M.C., Marsden. J.L., Kastner, C.L., and Kuecker, W.G. 1996. Sensory analysis and consumer acceptance of irradiated boneless pork chop. J. Food Sci. 61: 1261-1266.
Lynch, J.A., MacFie, H.J.H., and Mead, G.C. 1991. Effect of irradiation and packaging type on sensory quality of chilled-stored turkey breast fillets. J. Food Sci. Technol. 26: 653-668.
Mattison, M.L., Kraft, A.A., Olson, D.G., Walker, H.W., Rust, R.E., and James, D.B. 1986. Effect of low dose irradiation of pork loins on the microflora, sensory characteristics and fat stability. J. Food Sci. 51: 284-287.
Monk, J.D., Beuchat, L.R., and Doyle, M.P. 1995. Irradiation inactivation of food-borne microorganisms. J. Food Protect. 58:197-208.
Morrison, R.M. 1989. An economic analysis of electron accelerators and cobalt-60 for irradiating food. Technical Bulletin 1762. Economic Research Service, U.S. Dept. of Agriculture. Washington, D.C.
Murano, E.A. 1995a. Microbiology of irradiated foods. In "Food Irradiation: A Sourcebook," ed. E.A. Murano. Iowa State University Press, Ames, Iowa.
Murano, P.S. 1995b. Quality of irradiated foods. In "Food Irradiation: A Sourcebook," ed. E.A. Murano. Iowa State University Press, Ames, Iowa.
Niemand, J.G., Van der Linde, H.J., and Holzapfel, W.H. 1981. Radurization of prime beef cuts. J. Food Protect. 44: 677-681.
Niemand, J.G., Van der Linde, H.J., and Holzapfel, W.H. 1983. Shelf-life extension of minced beef through combined treatments involving radurization. J. Food Protect. 46: 791-796.
Palumbo, S.A., Jenkins, R.K., Buchanan, R.L., and Thayer, D.W. 1986. Determination of irradiation D-values for Aeromonas hydrophila. J. Food Protect. 49: 189-191.
Pauli, G.H. and Tarantino, L.M. 1995. FDA regulatory aspects of food irradiation. J. Food Protect. 58: 209-212. Resurreccion, A.V.A., Galvez, F.C.F., Fletcher, S.M., and Misra, S.K. 1995. Consumer attitudes toward irradiated food: Results of a new study. J. Food Protect. 58: 193-196.
Sanderson, D.C.W. 1991. Photostimulated luminescence (PSL): A new approach to identifying irradiated foods. In "Potential New Methods of Detection of Irradiated Food." Commission of the European Communities, Luxembourg.
Shin, S.Y., Kliebenstein, J., Hayes, D.J., and Shogren, J.F. 1992. Consumer willingness to pay for safer food products. J. Food Safety 13: 51-59.
Stevenson, M.H. 1992. Progress in the identification of irradiated foods. Trends Food Sci. Technol. 46: 262- 267.
Sudarmadji, S. and Urbain, W.M. 1972. Flavor sensitivity of selected animal protein foods to gamma radiation. J. Food Sci. 37: 671-672.
Taub, I.A., Kaprielian, R.A., Halliday, J.W., Walker, J.E., Angelini, P., and Merritt, C., Jr. 1979. Factors affecting radiolytic effects in food. Radia. Physics Chem. 14: 639-653.
Thayer, D.W. 1990. Food irradiation: Benefits and concerns. J. Food Qual. 13: 147-169.
Thayer, D.W. and G. Boyd. 1992. Gamma ray processing to destroy Staphylococcus aureus in mechanically deboned chicken meat. J. Food Sci. 57: 848-851.
Thayer, D.W., Boyd, G., and Jenkins, R.K. 1993. Lowdose gamma irradiation and refrigerated storage in vacuo affect microbial flora of fresh pork. J. Food Sci. 58: 717-719, 733.
Thayer, D.W., Boyd, G., Muller, W.S., Lipson, C.A., Hayne, W.C., and Baer, S.H. 1990. Radiation resistance of Salmonella. J. Indust. Microbiol. 5: 383-390.
WHO. 1994. Safety and nutritional adequacy of irradiated food. World Health Organization, Geneva.
WHO. 1997. Food irradiation. Press release WHO/68, Sept. 19. World Health Organization, Geneva.
Woods, R.J. and Pikaev, A.K. 1994. Interaction of radiation with matter. In "Applied Radiation Chemistry: Radiation Processing." John Wiley & Sons, New York.
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By David Crane defrev (at) gmail (dot) com All photos contained in this article were taken by DefenseReview.com, and are copyrighted. DefenseReview.com owns the copyright on these photos. The photos were shot with a Canon PowerShot S90 10-megapixel digital camera (still camera with video capability). April 5, 2010 Updated on 5/11/10 Kitty corner to the Lewis Machine & Tool (LMT) ... Read More »
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Remington R-25 Multi-Caliber Semi-Auto AR-10 Crossover Rifle for Tactical AND Hunting Applications
By David Crane defrev (at) gmail (dot) com Several weeks ago, DefenseReview had an interesting conversation with Ralph Lermayer, Editor of Read More »

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Kurt Busch is sizzling (Photo: Getty Images for NASCAR)
By Mike Mulhern
The Grand Prix of Monaco, the Indianapolis 500, and then the Coke 600. Makes for quite a full Sunday of racing.
It's also the point in the NASCAR season where drivers and teams can begin assessing their championship potential, as they prepare to head into the stock car tour's annual summer country-crisscross.
One big wild card so far this NASCAR season -- Kurt Busch.
The volatile Busch has learned to tame his famous temper and focus, focus, focus, and it's paying off.
He had the car to beat in Saturday night's All-Star race, though falling to Jimmie Johnson on the final pit stop. And Kurt is starting off the 600 weekend just as stout.
Busch ripped off a hot qualifying lap of 195.221 mph Thursday evening, near sunset, one of several drivers cracking the track record (193.708), and he was clocked at a stunning 203 mph into the corner. Credit crew chief Todd Berrier for the car, and credit Busch for getting that much speed out of the Chevy.
But even that wasn't good enough for the pole -- Toyota's Denny Hamlin, still on the comeback trail, pulled that off with a 195.624.
It was Hamlin's second pole of the season. He was on the pole at California's Auto Club Speedway. "And how did that turn out," Hamlin dead-panned, referring to the last lap crash while battling Joey Logano for the win at the Los Angeles track.
Recovered? "Everything feels good," Hamlin says. "Everything should be good."
Toyota took four of the top five in qualifying, Gibbs' men first, third and eighth.
Jimmie Johnson says at these speeds "Your committment level has to match the track's grip level...."
"It takes nerve to do it, and you've got to have a fast car," Hamlin said with a grin.
The sport's longest race will start around 6 p.m. ET Sunday, when Charlotte Motor Speedway is still hot and slick and unpredictable. And it will end about 10:30 p.m., with the track cooler and with more grip. The team chasing the changing track the best will probably have the best shot at winning.
One big question: will the final stretch Sunday be a full 60-lap (90-mile) gas run, or a 10-lap or so sprint?
Another question: will fuel mileage play a role?
Another Busch brothers show shaping up for the Charlotte Coke 600? (Photo: Getty Images for NASCAR)
Kurt and brother Kyle were easily the quickest in Thursday practice, though Kyle was only eighth in qualifying. The early line on the 600 looks to be shaping up as something of a replay of the All-Star: the Busch brothers versus Hendrick teammates Jimmie Johnson and Kasey Kahne...with Toyota's Joe Gibbs trio of Denny, Kyle and Matt serious threats for a top-three sweep.
Kenseth, off in the All-Star, for some reason, dismissed questions about what he might have here, qualifying inside of the second row. "We haven't been in race trim all day, but we are clearly happy with the speed we have in the car," said Kenseth, who has never renowned as a qualifier -- something that changed dramatically when he joined Gibbs this season.
Another possible question: Ford drivers, including Brad Keselowski. They haven't shown much speed so far. Keselowski is without crew chief Paul Wolfe again this week; Wolfe is on NASCAR suspension for that trick rear end at Texas. Keselowski was a disappointing 20th in quals; teammate Joey Logano was even further off, 31st.
"The Joe Gibbs teams are all hitting on all eight cylinders," Kurt Busch said. "But I think the race will come to us Sunday. I have such confidence in my team. To put the pedal down and have it stick....."
Denny Hamlin, after missing several races, with that injury, is mired 27th in the standings and needs to win and crack the top-20 to make a run at the championship (Photo: Getty Images for NASCAR)
Two of this week's hottest stories are Bruton Smith and Bruton Smith.
Smith made big waves when he said it was 70 percent sure that he would move the fall Charlotte 500 to Las Vegas next year, to put Las Vegas in the championship chase. He did back off a bit, saying it wasn't a done deal. However 70-30, the numbers he used, are pretty strong.
Jeff Gordon: "I can't imagine not racing here three times a year, or certainly two points races. I love racing here.
"It's nice to be home, and this is such a special track. People flock from all over the country not just because of the facility, but the Hall of Fame, the city itself, the team shops...
"At the same time Las Vegas makes great sense from a marketing standpoint. When we look at the sport and where we're at and how to grow it and get those seats filled, you would certainly think that a race in Las Vegas in October would do pretty well.
"I think Las Vegas deserves to have two races. I would not want to see us take away a race from here."
So just why did NASCAR's hand-picked panel of voters turn down Bruton Smith? How badly does that damage the credibility of the fledgling Charlotte Hall of Fame? (Photo: Getty Images for NASCAR)
The other Bruton Smith story -- he was again dissed by NASCAR's hand-picked panel of voters for the Charlotte Hall of Fame.
The credibility of this particular racing museum has been questioned almost from the day it opened in 2010, because NASCAR executives, who run it, have excluded a large swath of stock car racing legends.
And with NASCAR's voters again shunning Smith, a key sports figure here since he opened this track in 1960, the downtown museum may have lost its last bit of validity....certainly in relationship to the sport's original Hall of Fame at Darlington.
Meanwhile, with Jimmie Johnson's come-from-behind victory in last weekend's All-Star race, writers here are once again billing him as possibly the greatest NASCAR driver of all time.
Yes, Johnson is amazing, not just for his five championships and driving talents but for the seeming inevitability of it all -- no matter how far down he and team may be team, they are invariably a threat to fight back into contention.
Kenseth is a believer:
"People can say whatever they want about him, but I don't know how you can't say he's not the best ever," Kenseth says.
"You look at what he's done with Chad Knaus; nobody has ever put up numbers like that.
"Nobody has ever won five championships in a row and probably never will.
"They're amazing.
"It's cool to be part of that because someday you look back at history and 'Oh yeah, I raced against him.'
"But at the same time it stinks because you get beat so many times."
Matt Kenseth: this season's biggest winners says Jimmie Johnson may well be the best stock car racer of all time (Photo: Getty Images for NASCAR)
So it may be interesting, and ominous, that Johnson and crew chief Chad Knaus haven't used any of their season's tests yet, and have no particular plans to, either.
"Luckily all the (Hendrick) cars are running good, and we're able to sit on our test sessions right now and use them in the best manner possible -- hopefully on chase tracks. That would be the ideal situation," Johnson says.
"As we get through the summer, if we have a teammate that's near that cutoff point, and we need to get stronger at a regular-season racetrack, we can have that strategy in place too."
Johnson's own preference for a track to test at: Phoenix. "We finished second there in the spring, but we didn't have the confidence the race weekend we wanted to. We raced better than we expected to, finished better than we thought.
"But from our team's standpoint, that's probably the hottest track in our mind to test at."
Jimmie Johnson at the All-Star finish line. And how far back is the runner-up? (Photo: Getty Images for NASCAR)
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Pippa trained at the Hammond School of Dance, Chester and the Royal Ballet School. Originally from Liverpool, she has danced with Scottish Ballet, Wiener Ballet Theatre and The Royal Ballet and joined Northern Ballet in 1996. Pippa retired from performing in 2019.
Where were you born and raised?
At what age did you start dancing?
Age 9.
Where did you train?
The Hammond School and the Royal Ballet School.
Previous companies
Scottish Ballet, Wiener Ballet Theatre and the Royal Ballet.
Favourite Northern Ballet roles
Lucy (Dracula), Young Cathy (Wuthering Heights), Helena (A Midsummer Night's Dream), Juliet (Romeo & Juliet), Wendy (Peter Pan), Butterfly (Madame Butterfly), Clara (The Nutcracker), Madame De Tourvel (Dangerous Liaisons) and the Stepmother (Cinderella).
What do you like most about being a dancer?
Portraying different characters on stage and having so many worlds I can just step into.
If you could adapt one work into a ballet what would it be?
The Alchemist, a novel by Paulo Coelho.
What is your favourite book?
To Kill a Mockingbird by Harper Lee.
What is your favourite post-show meal?
Ratatouille with tofu.
How do you like to relax?
Reading and long country walks.
If you weren't a dancer what would you be?
I would be running an Animal Rescue Centre.