2004 Annual Report 1.What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? What does it matter? The purpose of this research is to improve the microbiological safety and shelf-life of food by treating it with ionizing radiation alone or in combination with other food processing technologies. The project addresses problems that have resulted in several recent outbreaks of foodborne disease and recalls due to microbial contamination of ground beef, poultry, processed and ready-to-eat meats, fruit, fruit juices, and vegetables. The effects of pasteurization doses of ionizing radiation (gamma, electron, or X-ray) will be determined on both foodborne pathogens and spoilage organisms and the chemistry and quality attributes of the associated food products (e.g. ground beef, poultry, processed and ready-to-eat meats, fruit, fruit juices, vegetables, sprouts, and seeds for sprouting). Of particular interest are the foodborne pathogens Escherichia coli O157:H7, Listeria monocytogenes, Salmonella spp., Shigella spp., Staphylococcus aureus, and Yersinia enterocolitica. Our previous research has demonstrated that both intrinsic and extrinsic factors influence the inactivation of foodborne pathogens. Some of these factors are: atmosphere; pH; temperature before, during and after irradiation; previous adaptation of the pathogen to stress; the genetic characteristics and repair mechanisms of the particular microorganism; the chemistry and physical characteristics of the food upon which the contaminating microorganisms are located; and competition between surviving pathogens and spoilage organisms under stressed conditions. Since food processing technologies with different mechanisms of action such as irradiation, heating, and modified atmosphere have produced greater pathogen inactivation than would be predicted from the sum of the individual processes, complementary and synergistic technologies will be investigated. The effects of irradiation with other processing or storage technologies with appropriate food additives on the quality attributes of each food will be determined. There have been several recent food product recalls and outbreaks of disease associated with the ingestion of contaminated ground beef, poultry, processed meats, food sprouts, juices, and fresh produce. Listeria monocytogenes and Yersinia enterocolitica can multiply at refrigeration temperatures and are post-processing contaminants of ready-to-eat products. Minor initial contamination of a carcass or of seed used to grow food sprouts can result in a major contamination of ground meat or food sprouts. This makes it especially difficult to ensure that the pathogen will not reach the consumer. Relatively little data exists on the inactivation of human pathogens in or on fresh produce, fruits, and fruit juices by treatment with ionizing radiation or the effect of such treatments on the quality attributes of those products. For ground beef and some ready-to-eat products, food irradiation may be the only effective means of treatment. The effects of substrate and processing variables on microbial inactivation and quality attributes need to be determined for many products and pathogens. The objective of ARS National Program 108 is to determine how to reduce the levels of microbial pathogens in food products. The research conducted in this project focuses directly on increasing the microbial safety of food and addresses National Program 108 Food Safety Goal 2.3 as described in the National Program Action Plan, and component(s) 2.3.1.4, 2.4.1.2, 2.4.1.5, 2.4.1.4, 2.4.1.6, 2.5.1.3, 2.6.1.1. 2.List the milestones (indicators of progress) from your Project Plan. Year 1 (FY2001) Publication of initial studies on the inactivation of L. monocytogenes on frankfurters by ionizing radiation and competition of L. monocytogenes with indigenous microflora on irradiated turkey under modified atmosphere. Publication of initial studies on radiation inactivation of Salmonella and E. coli O157:H7 on alfalfa seeds and sprouts, and chemical/EPR detection methods for irradiated sprout seeds. Publication of initial study on the radiation resistance of Salmonella in orange juice. Completion of the modeling of the effects of irradiation temperature on the survival of E.coli O157:H7, Salmonella, and S. aureus. Year 2 (FY2002) Completion of studies of the effects of the composition of the batter used to make frankfurters on the survival of pathogens during irradiation. Continuation of research on the use of irradiation to eliminate foodborne pathogens from seeds and sprouts, to include seeds and sprouts other than alfalfa. Continuation of studies on the inactivation of salmonella in juice by irradiation, and on the quality of irradiated juice and initiation of studies on the use of irradiation processing to inactivate pathogens on fresh and frozen fruit and produce. Publish studies on the effect of plasmid-mediated virulence on the radiation resistance of Y. enterocolitica. Completion of studies on the effects of irradiation in combination with modified atmosphere packaging to extend the shelf-life of lamb. Year 3 (FY2003) Publication of studies exploring the use of irradiation inactivation of foodborne pathogens on food sprouts and seed used for the growth of food sprouts, fruits, and fruit juices. Completion of initial studies on the use of irradiation to eliminate pathogenic bacteria from ground meat, poultry, and processed meats, alone and in combination with modified atmosphere. Completion of studies on the effect of ionizing radiation on Y. enterocolitica virulence plasmid maintenance. Year 4 (FY 2004) Publication of completed studies on the inactivation of L. monocytogenes on frankfurters and using irradiation and determine the effect of irradiation on the competition of L. monocytogenes with indigenous microflora on irradiated turkey under a modified atmosphere. Completion of additional studies on the inactivation of Salmonella spp. in juice by ionizing radiation. Publication of terminal studies on Salmonella and E. Coli O157:H7 on seeds and sprouts, chemical and spectrometric (Electro Paramagnetic Resonance) detection of irradiated sprout seeds, and the effect of irradiation on seeds and on the yield of sprouts. Publication of the modeling of the effects of irradiation processing temperature on the survival of E. Coli O157:H7, Salmonella spp., Y. enterocolitica, and S. aureus in ground beef and pork. Year 5 (FY 2005) Continuation of research on the effect of ionizing radiation on fresh and processed fruits and fruit juices, vegetables, and complex ready-to-eat foods for improvement of microbiological safety, while maintaining product quality, is expected. This is especially important in regards to the lack of data regarding the radiation resistance of emerging pathogenic bacteria and those of interest for biosecurity issues. Initiation and continuation of research on the generation of radiolytic products such as furan(s), volatile sulfur compounds and 2-alkylcyclobutanones in processed meats, fruit juices, and complex ready-to-eat foods, accompanied by determination of toxicological safety of unique radiolytic compounds using short-term genetic toxicology and gene expression assays. Evaluate the efficacy of ionizing radiation, alone and in combination with other physical of chemical treatments, on the survival of pathogenic bacteria existing in biofilms that form on foods and food contact surfaces. As with all research modification will be made as new areas of research become apparent and research requests are made by stakeholders. 3.Milestones: A. List the milestones that were scheduled to be addressed in 2004. How many did you fully or substantially meet in 2004 and indicate which ones were not fully or substantially met, briefly explain why not, and your plans to do so. The milestones for FY2004, which are consistent with NPS Program 108 goals, have all been substantially met and are listed below: Studies on the inactivation of L. monocytogenes on frankfurters and processed meat batter, competition of L. monocytogenes with indigenous microflora on irradiated turkey under a modified atmosphere, the effect of irradiation on L. monocytogenes on raw and cooked turkey meat, were completed and published. Studies on the inactivation of Salmonella spp. in orange juice by ionizing radiation were completed and published. Studies on the radiation resistance of Salmonella and E. Coli O157:H7 on alfalfa seeds and sprouts, chemical detection of irradiated sprout seeds, and the effect of irradiation of alfalfa seeds on the yield of sprouts were completed and published. Publish the modeling on the effects of irradiation processing temperature on the survival of E. Coli O157:H7, Salmonella spp., and S. aureus in ground beef, and Y. enterocolitica in ground pork, and published the results. Studies on the effect of irradiation on the microbiological safety and quality attributes of processed apples were initiated. Initiated and completed research on the sensory quality of irradiated ground beef supplied as part of the National School Lunch Program at the request of USDA FNS and AMS. (Research requested by stakeholder). Completed and published initial studies on the genotoxicity of 2-dodecylcyclobutanone (2-DCB), a compound unique to irradiated foods, at the request of USDA FNS and AMS (Research request by stakeholder). B. List the milestones that you expect to address over the next 3 years (FY 2005, 2006, and 2007). What do you expect to accomplish year by year, over the next 3 years under each milestone? The year 5 milestones are listed below with a description of the anticipated outcomes. A new project plan will be developed to undergo OSQR review, with subsequent implementation beginning in 2006. Year 5 (FY2005) Continuation of research on the effect of ionizing radiation on fresh and processed fruits and fruit juices, vegetables, and complex ready-to-eat foods for improvement of microbiological safety, while maintaining product quality, is expected. This is especially important in regards to the lack of data regarding the radiation resistance of emerging pathogenic bacteria and those of interest for biosecurity issues. Initiation and continuation of research on the generation of radiolytic products such as furan(s), volatile sulfur compounds and 2-alkylcyclobutanones in processed meats, fruit juices, and complex ready-to-eat foods, accompanied by determination of toxicological safety of unique radiolytic compounds using short-term genetic toxicology and gene expression assays. Evaluate the efficacy of ionizing radiation, alone and in combination with other physical of chemical treatments, on the survival of pathogenic bacteria existing in biofilms that form on foods and food contact surfaces. As with all research modification will be made as new areas of research become apparent and research requests are made by stakeholders. Year 6 (FY 2006) Assuming that the subsequent project plan continues the research along its present course, we anticipate: Continuation of research on the effect of ionizing radiation on processed meats, fresh and processed fruits and fruit juices, vegetables, and complex ready-to-eat foods for improvement of microbiological safety, while maintaining product quality. This is especially important in regards to the lack of data regarding the radiation resistance of emerging pathogenic bacteria and those of interest for reasons of biosecurity issues. Continuation of research on the efficacy of ionizing radiation, alone and in combination with other physical of chemical treatments, on the survival of pathogenic bacteria existing in biofilms that form on foods and food contact surfaces. Initiation of research on the on the use of ionizing radiation, alone and in combination with other thermal and non-thermal technologies, to reduce levels of pathogenic spores and surrogate viruses from food products. Year 7 (FY2007) The previous investment in the use of ionizing radiation, alone or in combination with other non-thermal processing technologies and mild-thermal interventions, for the purpose of reducing pathogen levels while limiting changes to food chemistry and quality, raises the possibility of developing combinatorial processing technologies that could reduce both pathogen levels and carcinogen levels in foods. The development of combinatorial processes should be pursued in order to decrease the incidence of foodborne illness while simultaneously decreasing diet associated cancer risk in the U.S. population. 4.What were the most significant accomplishments this past year? A. Single most significant accomplishment during FY 2004: The 2002 Farm Bill and the Richard B. Russell National School Lunch Act allow irradiated ground beef, on a voluntary basis, to be distributed in the National School Lunch Program (NSLP) in order to prevent foodborne illness caused by bacteria such as E.coli O157:H7. However, there were concerns, based on questions from school district administrators and parents, that irradiation might change the sensory quality of the product. Frozen ground beef patties distributed as a part of the NSLP, irradiated under commercial conditions at Eastern Regional Research Center (ERRC), could not be distinguished from non-irradiated ground beef when tested for overall liking, flavor, taste, texture or aftertaste as determined by untrained panelists. Irradiation does not affect palatability of frozen ground beef patties used in the NSLP. Results of the study completed by Food Safety Intervention Technologies Management Unit (FSIT-RU) scientists are being provided to schools by USDA FNS as part of the USDA NSLP educational program on food irradiation. Orders for frozen irradiated ground beef patties have now been placed by school districts. Action Plan Component(s) 2.3.1.4. B. Other significant accomplishment(s), if any: Anti-technology and anti-globalization groups have claimed that 2-dodecylcyclobutanone (2-DCB), a chemical unique to irradiated food, is mutagenic and therefore carcinogenic. 2-DCB was tested in a battery of five short-term genetic toxicology tests, with no evidence being obtained that it caused mutations in DNA, rearrangement of chromosomes, or increased the expression of genes that are responsible for repairing damaged chromosomes. The research completed at ERRC by FSIT-RU scientists, in cooperation with scientists at UCLA and Edinboro Univ. of PA, showed that claims of 2-DCB's mutagenicity were erroneous. Results of the studies are now being distributed as part of the USDA FNS NSLP educational program for irradiated ground beef in order to provide school district administrators and parents with accurate and factual information on the toxicological safety of 2-DCB and irradiated foods. Action Plan Component(s) 2.3.1.4. Consumption of leaf lettuce has been implicated as a factor in outbreaks of food borne illness. Four types of leaf lettuce commonly used in salads (Boston, Red Leaf, Green Leaf, and Iceberg) were inoculated with Salmonella or L. monocytogenes and treated with ionizing radiation by FSIT-RU scientists. The radiation dose required to achieve the FDA's recommended 99.999 percent reduction of pathogenic bacteria on the four lettuce types was approximately 1.0 kGy for L. monocytogenes, and ranged from 1.15 to 1.55 kGy for Salmonella among the lettuce types. These results show that irradiation, when included as part of an overall Hazard Analysis and Critical Control Point Plan (HACCP) to reduce levels of pathogenic bacteria on salad vegetables, can provide safer food to consumers. This data will help the FDA evaluate a petition, currently under review, that would allow irradiation of ready-to-eat foods. Action Plan Component(s) 2.3.1.4, 2.2.1.5. L. monocytogenes, a food-borne bacterium responsible for numerous food-borne illness outbreaks and product recalls, can sometimes be found as a contaminant on leafy vegetables. Endive leaves inoculated with L. monoctyogenes, and treated with ionizing radiation and stored under modified atmosphere conditions, demonstrated a reduction in the prevalence and re-growth of L. monocytogenes relative to products stored in air. The results indicate that irradiation and modified atmosphere packaging can be used in combination to reduce pathogen levels and prevent the re-growth of radiation damaged L. monocytogenes during post-irradiation refrigerated storage. The study completed by FSIT-RU scientists can be used by the food processing industry to provide safer products for consumers and by the FDA to evaluate a petition to allow irradiation of ready-to-eat foods. Action Plan Component(s) 2.3.1.4, 2.4.1.3, 2.4.1.5. Fresh fruits and vegetables are rich in antioxidants which exhibit properties that prevent cancer and reduce mortality due to cancer and heart diseases. The impact of ionizing radiation on the antioxidant capacity of fresh fruits and vegetables is unclear. Therefore, a study was conducted by FSIT-RU scientists to investigate radiation-induced changes in antioxidant capacity of three common salad greens; romaine lettuce, iceberg lettuce, and endive. Results indicated that irradiation enhanced antioxidant content of the salad green vegetables in a dose dependent fashion. At a radiation dose of 1 kGy, the maximum dose currently allowed by regulatory agencies for treatment of fruits and vegetables, antioxidant capacity was increased by at least 14 percent in lettuce and endive after 8 days of post-irradiation storage. These results suggest that irradiation folowed by stroage increased nutritional quality of vegetables in addition to the well- known benefit of improving microbial food safety. This information can be used by the food processing industry to provide safer products for consumers and by the FDA to evaluate a petition to allow irradiation of ready-to-eat foods. Action Plan Component(s) 2.3.1.4, 2.5.1.1. Consumption of fresh-cut vegetables (salad greens) in the USA has increased in recent years. Fresh-cut vegetables are occasionally contaminated with human pathogens. Ionizing radiation can eliminate pathogenic bacteria, however, like other processing technologies, irradiation can cause degradation of quality when used in excess. This study was conducted to investigate the radio-sensitivity of thirteen common fresh-cut vegetables using a tissue electrolyte leakage measurement. Our results showed electrolyte leakage increased linearly with higher radiation dose for all vegetables, and that each vegetable was different as to the radiation dose that significantly increased electrolyte leakage. The findings will help the fresh-cut vegetable industry to select suitable radiation doses for different vegetables for the enhancement of microbiological safety and provides the industry with a method to evaluate the effect of irradiation on vegetable quality. Action Plan Component(s) 2.3.1.4, 2.4.1.2, 2.4.1.5 Distribution of pre-made ready-to-eat (RTE) sandwiches is a multi-billion dollar industry in the U.S. The foodborne pathogen L. monocytogenes is a common contaminant on pre-made RTE sandwich products. L. monocytogenes was inoculated onto turkey and cheese tortilla wraps that are popular with consumers, and the radiation resistance of the bacteria determined. A radiation dose of 2.0 kGy was found to eliminate 99.99 percent of the L. monocytogenes inoculated onto the turkey and greater than 99.999 percent of the bacteria on the cheese and tortilla portions. Irradiation, when utilized as a terminal intervention step as part of an overall HACCP plan, will help manufacturers provide safer sandwich products to consumers and help the FDA evaluate a petition to allow irradiation of RTE foods. Action Plan Component (s) 2.3.1.4, 2.6.1.1. C. Significant activities that support special target populations: None. 5.Describe the major accomplishments over the life of the project, including their predicted or actual impact. The outbreaks of food-borne disease in which raw sprouts were implicated have in many cases been traced to pathogen-contaminated seeds. Food Safety Intervention Technologies Research Unit scientists determined the effect of gamma irradiation on seeds for sprouting for broccoli, alfalfa and radish. Satisfactory yields of sprouts were achieved with seeds irradiated at doses which would eliminate 99.999% of E. Coli O157:H7 and in excess of 99% of Salmonella. Additional work has indicated that the radiation dose required to eliminate S. Mbandaka from naturally contaminated seeds is dependent on the initial contamination level. Irradiation of seeds for sprouting will provide safer sprouts for consumers. Action Plan Component (s) 2.3.1.4, 2.4.1.2. Project Plan Milestone(s) 1, 2 and 3. Outbreaks of food-borne illness have been associated with salad vegetables. Food Safety Intervention Technologies Research Unit Scientists inoculated the pathogen E. coli O157:H7 onto four different types of lettuce and determined that a radiation dose of 1.0 kGy reduced levels of the pathogen by 99.99% without affecting produce quality. This will allow processors to provide consumers with produce that is both organoleptically pleasing and microbiologically safer and also meet regulatory goals for reduction of pathogens as part of an overall HACCP plan. Action Plan Component(s) 2.3.1.4, 2.4.1.2, 2.4.1.5, 2.2.1.5. Project Plan Milestone(s) 2 and 3. Several food-borne illness outbreaks and recalls of processed meats have occurred due to contamination with L. monocytogenes. Multiple L. monocytogenes strains isolated from frankfurters following a major food-borne illness outbreak were tested for radiation resistance. This was the first such study conducted on L. monocytogenes strains isolated from processed meats following a major listeriosis outbreak. A radiation dose between 2.5 to 3.5 kGy was sufficient to inactivate 99.999% of the pathogen on the surface of the frankfurters depending on the formulation of the processed meat. The quality of the frankfurters was not affected by irradiation. This meets the goal established by the Food and Drug Administration to reduce levels of this food-borne pathogen. Action Plan Component(s) 2.3.1.4, 2.6.1.1. Project Plan Milestone(s) 1, 2 and 3. Research Scientists determined that a mixture of the food additives sodium diacetate and potassium lactate in bologna formulations decreased the radiation dose needed to inactivate 99.999% of L. monocytogenes inoculated onto bologna from 3.0 to 2.5 kGy. The combination of irradiation and additives also inhibited the growth of radiation damaged L. monocytogenes for two months during refrigerated storage. The quality of bologna was not affected by either irradiation or the additives. This meets the goal established by the Food and Drug Administration for a 99.999% reduction of this food-borne pathogen and will help manufacturers provide safer products to consumers.L. monocytogenes is a post-process contaminant on ready-to-eat meats such as bologna that has been responsible for several well-publicized food-borne illness outbreaks. Action Plan Component(s) 2.3.1.4., 2.6.1.1 Action Plan Component(s) 2.3.1.4, 2.6.1.1. Project Plan Milestone(s) 1, 2 and 3. The food-borne pathogen L. monocytogenes is a frequent post-process contaminant on processed meats such as ham. Ionizing radiation and vacuum-steam-vacuum, both non-thermal processing technologies, can eliminate the pathogen from ham, but that excessive use of the either technology alone can change the organoleptic quality of the product. Research Unit scientists inoculated Listeria into ham and found that use of 1.5 kGy ionizing radiation in combination with two cycles of vacuum-steam-vacuum could eliminate 99.999% of the microorganism from ham surfaces without affecting ham quality. Processors may use this technology to provide safer processed meat products to consumers and meet regulatory agency goals for reduction of the pathogen. Action Plan Component 2.3.1.4., 2.3.1.5. Project Plan Milestone(s) 1, 2 and 3. 6.What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end-user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? The results of our studies have been presented at National and International meetings specifically organized for the transfer of new developments in the irradiation of foods to the associated food processing industries and the irradiation industry. Several publications have been cited in petitions submitted by industry to regulatory agencies, or transferred to regulatory agencies directly, to allow irradiation of food products. 7.List your most important publications in the popular press and presentations to organizations and articles written about your work. Fan, X., Niemira, B. A., Thayer, D. W. 2004. Low dose ionizing radiation of fruit juice: benefits and concerns. In: Komolprasert, V., Morehouse, K. M., editors. Irradiation of Food and Packaging: Recent Developments. American Chemical Society. Washington DC. p. 138-150. Rajkowski, K. T., Fan, X. 2004. Ionizing radiation of seeds and sprouts A review. In: Komolprasert, V., Morehouse, K. M., editors. Irradiation of Food and Packaging: Recent Developments. American Chemical Society. Washington DC. p. 107-116. Sommers, C.H. ,Keser, N., Fan, X., Wallace, F. M., Novak, J. S., Handel, A.P., Niemira, B. A. 2004. Irradiation of Ready-To-Eat Meats-Eliminating Listeria monocytogenes While Maintaining Product Quality. In: Komolprasert, V., Morehouse, K. ,editors. Irradiation of Food and Packaging: Recent Developments. American Chemical Society. Washington, D.C. p. 77-89. Sommers C. 2003. Improving the Microbiological Safety of Poultry by Irradiation. FeedInfo News Service Scientific Reviews. p.1-4. Available at: http://www.feedinfo.com. Review Publications ARGENTA, L.C., FAN, X., MATTHEIS, J.P. INFLUENCE OF 1-METHYLCYCLOPROPENE ON RIPENING, STORAGE LIFE AND VOLATILE PRODUCTION BY 'D'ANJOU' CV. PEAR FRUIT. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY. 2003. v. 51(13). p. 3858-3864. FAN, X., NIEMIRA, B.A., BAXENDALE, K.J. SENSORIAL NUTRITIONAL AND MICROBIOLOGICAL QUALITY OF FRESH CILANTRO LEAVES AS INFLUENCED BY IONIZING IRRADIATION AND STORAGE. FOOD RESEARCH INTERNATIONAL. 2003. V. 36. P. 713-719. FAN, X., THAYER, D.W., SOKORAI, K.J. CHANGES IN GROWTH AND ANTIOXIDANT STATUS OF ALFALFA SPROUTS DURING SPROUTING AS AFFECTED BY GAMMA IRRADIATION OF SEEDS. JOURNAL OF FOOD PROTECTION. 2004. V. 67. NO. 3. P. 561-566. FAN, X. IONIZING RADIATION INDUCES FORMATION OF MALONDIALDEHYDE, FORMALDEHYDE AND ACETALDEHYDE FROM CARBOHYDRATES AND ORGANIC ACID. JOURNAL OF AGRICULTURE AND FOOD CHEMISTRY. 2003. V. 51. P. 5946-5949. Fan, X., Sommers, C.H., Sokorai, K.J. 2004. Irradiation and antioxidants affect volatile sulfur compounds, lipid oxidation and color of ready-to-eat turkey bologna. Journal of Agricultural and Food Chemistry. 52:3509-3515. MATTHEIS, J.P., FAN, X., ARGENTA, L. MANAGEMENT OF CLIMACTERIC FRUIT RIPENING WITH 1-METHYLCYCLOPROPENE, AN INHIBITOR OF ETHYLENE ACTION. PROCEEDINGS OF PLANT GROWTH REGULATORS SOCIETY OF AMERICA. pp. 20-25. 2003. SOMMERS, C.H., FAN, X., NIEMIRA, B.A., SOKORAI, K.J. RADIATION (GAMMA) RESISTANCE AND POST-IRRADIATION GROWTH OF LISTERIA MONOCTYTOGENES SUSPENDED IN BEEF BOLOGNA THAT CONTAINED SODIUM DIACETATE AND POTASSIUM LACTATE. JOURNAL OF FOOD SAFETY. 2003. V. 66. P. 2051-2056. NIEMIRA, B.A. RADIATION SENSITIVITY AND RECOVERABILITY OF LISTERIA MONOCYTOGENES AND SALMONELLA ON FOUR LETTUCE TYPES. JOURNAL OF FOOD SCIENCE. 2003. V. 68 (9). P. 2784-2787. Sommers, C.H. 2003. 2-dodecylcyclobutanone, a chemical produced by irradiation of fat containing foods, does not induce mutations in the escherichia coli tryptophan reverse mutation assay. Journal of Agriculture and Food Chemistry. 51:6367-6370. Fan, X., Rajkowski, K.T., Thayer, D.W. 2003. Quality of alfalfa sprouts grown from irradiated seeds. Journal of Food Quality. 26:165-176. Sommers, C.H., Sohistl, R.H. 2004. 2-dodecylcyclobutanone does not induce mutations in the salmonella mutagenicity test or intrachromosomal recombination in saccharomyces cerevisae. Journal of Food Protection. 67:1293-1298. Gregoire, O., Cleland, M.R., Mittendorfer, J., Dababneh, S., Ehlermann, D.A., Fan, X., Kappeler, F., Logar, J., Meissner, J., Thayer, D.W. 2003. Safety food irradiation with high energy x-rays: theoretical expectations and experimental evidence. Journal of Radiation Physics and Chemistry. 67(2):169-183.