Progress 10/01/00 to 09/30/06
Outputs
Alternative methods to enhance the safety of sprouts and fruit juices have been developed. Ultraviolet light treatment system for juices was developed and proven to achieve a 5-log reduction against the pertinent pathogens Escherichia coli O157:H7 and Cryptosporidium parvum. UV is a non-thermal processing method that was shown not to change the flavor of apple cider compared to thermal treatment of cider. The effectiveness of UV was determined not to be influenced by varying levels of acidity. Different blends of apple cider and different fruit and vegetable juices were used to determine the UV exposure required to achieve the minimum 5-log reduction. The cost of operation for the UV treatment was 0.12 dollars for one hour of operation which equaled the treatment of up to 420 gallons of cider. This effective and economical alternative has resulted in more than 250 commercial UV units in use across the US. In an attempt to enhance the safety of sprouts, mild heat
treatments of 55 celcius for 4 to 8 days was shown to be effective in achieving a greater than 5-log reduction in E. coli O157:H7 and Salmonella spp. on alfalfa and mung bean seeds. The germination rates for the seeds after 4 to 8 days of heat treatment were not significantly affected. The treatment could be used on seeds prior to selling at the seed supplier or alternatively by the sprout producer.
Impacts
Effective and inexpensive treatment methods were developed for small juice manufacturers and sprout producers. These findings will allow for small juice and sprout producers to guarantee the safety of their products and protect their consumers while at the same time, allow them to remain in business due to the low cost of equipment and operation.
Publications
- No publications reported this period
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Progress 01/01/05 to 12/31/05
Outputs
Additional studies have been conducted to assess the potential of ultraviolet light for the inactivation of pathogens associated with milk that is intended for cheese production. Raw bovine and goat milk were inoculated a 5 strain cocktail of Listeria monocytogenes of various linages associated with milk and cheese foodborne outbreaks. The inactivation kinetics of Listeria monocytogenes was established and it was determined that 15.8 mJ/cm2 of UV exposure was required to achieve a 5-log reduction. The fat micelles were found to absorb the ultraviolet light and increasing levels of milk fat required increasing amounts of UV exposure. At the levels of UV exposure required to achieve a 5-log reduction, lipid oxidation was observed. In the fall of 2004, an apple cider outbreak in New York State occurred that was responsible for more than 200 people becoming ill due to contaminated raw apple cider. In response to the outbreak, I provided guidance to the New York Apple
Association to propose that all apple cider receive a minimum 5-log reduction through pasteurization or ultraviolet treatment regardless of retail or wholesale production. This motion subsequently became New York State legislation as Senate Bill # 4356-B effective January 8, 2006. I was contacted for numerous magazine and newspaper interviews and invited presentations to explain the reasoning behind the law and what the law entails itself. The strain of E. coli O111 that was implicated in the cider outbreak is currently being investigated for its thermal and UV sensitivity to ascertain whether current pasteurization and UV treatments are sufficient to ensure a 5-log reduction as required by law.
Impacts
As a result of the this research, the safety of apple cider will be assured that will benefit consumers. Consumer, regulatory and production level education will provide a better understanding of apple cider risks and processing options available to guarantee the safety of this product.
Publications
- Matak, K. E., J. J. Churey, R. W. Worobo, S. S. Sumner, E. Hovingh, C. R. Hackney, and M. D. Pierson. 2005. Efficacy of UV Light for the Reduction of Listeria monocytogenes in Goats Milk Intended for Cheese Production. J. Food Prot. 68. 10:2212-2216.
- M. Moake, Padilla-Zakour, O. I., and R. W. Worobo. 2005. Comprehensive review of patulin control methods in foods. Comprehensive Rev. in Food Sci. and Food Safety. 1: 8-21.
- Golden, D., Worobo, R. W., and C. S. Ough. 2004. Dimethyl Dicarbonate and Diethyl Dicarbonate. In Antimicrobials in Foods. Third Edition. Marcel Dekker, Inc. 305-327.
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Progress 01/01/04 to 12/31/04
Outputs
The use of ultraviolet light to achieve a 5-log reduction in E. coli O157:H7 and Cryptosporidium parvum oocysts in apple cider was established by the researchers previously. The effect of apple varieties and pH on the inactivation of E. coli in apple cider was examined. A total of eight different apple varieties were used to make apple cider from each variety. Each apple cider was inoculated with three different E. coli O157:H7 strains. The inoculated cider was then exposed to 14 mJ of UV light using the CiderSure 3500 processing unit and the log reductions between ciders were compared. From the results, there was no effect of apple variety on the inactivation of E. coli O157:H7. To determine if pH of apple cider affected the UV inactivation of E. coli, apple cider was adjusted between a pH range of 2.99 to 4.41 using malic acid. The apple cider with different pH values was inoculated with E. coli ATCC 25922, a surrogate for E. coli O157:H7, and immediately exposed to
14 mJ of ultraviolet light using the CiderSure 3500 unit. The treated samples were immediately plated to minimize acid injury. From the results, the pH of the cider does not affect the UV inactivation in apple cider.
Impacts
Fruit and vegetable processors will benefit from the research findings through the identification of processing and production practices that will offer additional methods to enhance the safety for fruit and vegetable products .
Publications
- A. Quintero-Ramos, Churey, J., Hartman, P., Barnard, J. and R. W. Worobo. 2004. Modeling of Escherichia coli: O157:H7 Inactivation by UV Irradiation at different pH Values in Apple Cider. 2004. Journal of Food Prot. 67, 6: 1153-1156.
- N. Basaran, A. Quitero-Ramos, Churey, J. J., and R. W. Worobo. 2004. Influence of apple cultivars on inactivation of different Strains of Escherichia coli O157:H7 in apple cider by UV irradiation. Applied and Environmental Microbiology.70: 6061-65.
- H. Hu, Churey, J.J. and R. W. Worobo. 2004. Heat treatments to enhance the safety of contaminated mung bean seeds. Journal of Food Prot.. 67, 6: 1257-1260.
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Progress 01/01/03 to 12/31/03
Outputs
We have continued to investigate pathogen decontamination methods for the production of seed sprouts. The most promising treatment studied thus far is the application of mild heat treatments (50 degrees C) of the seeds for a minimum of 3 days prior to the sprouting process. This mild heat treatment resulted in a greater than 5-log CFU/g reduction in Escherichia coli O157:H7 and Salmonella enterica. Five cocktail strains of both Escherichia coli O157:H7 and Salmonella enterica were used to establish the reduction with the varying heat treatments. The treated seeds when sprouted did not show the re-growth of Escherichia coli O157:H7 or Salmonella enterica which suggests that the pathogens were completely eliminated for the seed samples used for the sprouting study. There was no effect on the germination rate of the seeds that were subjected to the mild heat treatment. This decontamination treatment appears to be a viable decontamination treatment for seed sprout
producers that does not involve the use of extremely high levels of hypochlorite and is an effective means to eliminate pathogens introduced with the seeds. Research investigating the potential use of ultraviolet light as means to decontaminate apple cider and other fruit juices is continuing. The effect of varying levels of acidity and UV dose in apple cider and the effect on the reduction of Escherichia coli was investigated. The pH of apple cider was between 2.99 and 4.41 using malic acid as the acidifying agent while the UV dose was varied between 1.8-20.3 mJ. It was determined that pH had no effect on the reduction of Escherichia coli. Ultraviolet light doses of 6.5 mJ or greater resulted in a minimum 5-log reduction of Escherichia coli. Unlike thermal inactivation kinetics, ultraviolet light inactivation is not effected by pH and thus, apple cultivar composition or pH of the apple cider does not have to be taken into consideration for ultraviolet processing of apple cider.
Impacts
Fruit and vegetable processors will benefit from the research findings through the identification of processing and production practices that will offer additional methods to enhance the safety for fruit and vegetable products .
Publications
- Tandon, K., Worobo, R.W., Churey, J.J., and O.I. Padilla-Zakour. 2003. Storage quality of pasteurized and UV treated apple cider. Journal of Food Processing and Packaging. 27, 1: 21-35.
- Dogan-Halkman,-H-B; Cakir,-I; Keven,-F; Worobo,-R-W; Halkman,-A-K. 2003. Relationship among fecal coliforms and Escherichia coli in various foods. European-Food-Research-and-Technology. 216(4): 331-334.
- Padilla-Zakour, O. I., Tandon, K. S., and R. W. Worobo. 2003. Increasing the shelf-life of sweet apple cider without adding preservatives. Poster 86-6. IFT Annual Meeting. Chicago, IL.
- Hu, H., Churey,J. J., and R. W. Worobo. 2003. Heat treatments to enhance the safety of Escherichia coli O157:H7 inoculated mung bean seeds. Poster 104A-9. IFT Annual Meeting. Chicago, IL.
- Basaran, N. and R. W. Worobo. 2003. Inactivation of Escherichia coli O157:H7 in eight single cultivar apple ciders using ultraviolet light Poster 29G-30. IFT Annual Meeting. Chicago, IL.
- Basaran, N. 2003. Non-thermal processing alternatives for apple cider. Masters thesis. Cornell University, Ithaca, NY.
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Progress 01/01/02 to 12/31/02
Outputs
Research investigating effective methods for the decontamination of finished sprouts and sprout seeds prior to sprouting is continuing. Sprout associated foodborne illness outbreaks have been attributed to contamination of sprouts with E. coli O157:H7 and Salmonella spp. Previously, we investigated the effectiveness of dimethyl dicarbonate to inactivate E. coli O157:H7 on finished sprouts. During the past year, we have examined the effectiveness of dimethyl dicarbonate on the decontamination of Salmonella spp. contaminated finished mung bean and alfalfa sprouts. Similar conditions as the previous research (7,500 and 10,000 ppm of dimethyl dicarbonate for 15 minutes) were employed but using a 5 strain cocktail of Salmonella species. The treatment resulted in a 5-log reduction of Salmonella spp. with alfalfa sprouts and approximately 3.5 log reduction of Salmonella spp. with mung bean sprouts. Decontamination of Salmonella spp. and E. coli O157:H7 inoculated seeds using
dimethyl dicarbonate was also investigated. Various levels of dimethyl dicarbonate (500 to 10,000 ppm) and different treatment times (15-30 minutes) were tested. The maximum log reduction achieved was 3-log with both Salmonella spp. and E. coli O157:H7 on alfalfa and mung bean seeds. Presently, we are investigating other potential decontamination strategies for the seeds prior to sprouting. This work has just been initiated but some of the treatments look promising. A separate research project focused on the efficacy of ultraviolet irradiation to inactivate Cryptosporidium parvum oocysts in apple cider using the same ultraviolet irradiation (14.3 mJ) that is used to achieve a greater than 5-log reduction of E. coli O157:H7 in apple cider using the CiderSure commercial UV processing unit. This work was done in collaboration with FDA CFSAN (Washington, DC) and the CDC (Atlanta, GA). The results of this experiment showed that 14.3 mJ of ultraviolet irradiation exposure applied to apple
cider achieved a greater than 6-log reduction of Cryptosporidium parvum oocysts.
Impacts
The intervention strategies being investigated for the decontamination of foodborne pathogens in alfalfa sprouts may have application to other fruit and vegetable commodities. The ultimate goal of this research is to enhance the safety of high risk fruit and vegetable crops that have been implicated in numerous foodborne illness outbreaks.
Publications
- Hanes,D. E. Orlandi, P.A. Burr, D.H. Miliotis, M.D. Bier, J.W. Jackson, J.G. Arrowood, M.J. Churey, J.J. and Worobo R. W. 2002. Inactivation of Cryptosporidium parvum Oocysts in Fresh Apple Cider using Ultraviolet Irradiation. Appl. Environ. Micro. 68(8): 4168-4172.
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Progress 01/01/01 to 12/31/01
Outputs
Several projects that focus on enhancing the safety of fruits and vegetables have been initiated. Seed sprouts (alfalfa and mung bean) have continued to cause foodborne illness outbreaks in the US. Sprouts are normally consumed raw and no decontamination strategies have been proposed. Decontamination of potentially contaminated seeds using chlorine is currently being used by the sprout industry but pathogen contamination during the sprouting process is still possible and continues to pose a food safety risk. Dimethyl dicarbonate (DMDC) has been investigated as a sprout decontamination treatment that does not alter the quality of the sprout. Using 7,500 and 10,000 ppm of DMDC in water for 15 minutes resulted in a 5.0 and 2.4 log reduction of E. coli O157:H7 on alfalfa and mung bean sprouts respectively. A water wash alone for 15 minutes for E. coli O157:H7 inoculated alfalfa and mung bean sprouts resulted in a 1.9 and 1.2 log reduction for alfalfa and mung bean sprouts
respectively. These results suggest that DMDC (7500 ppm) is effective in achieving a 5.0 log reduction of E. coli O157:H7 on alfalfa sprouts while 10,000 ppm of DMDC achieves a 2.4 log reduction on mung bean sprouts.
Impacts
This treatment offers sprouts producers a possible final treatment of the seed sprouts to enhance the safety against pathogens that may increase in numbers during the sprouting process
Publications
- No publications reported this period
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