Progress 10/01/02 to 09/30/07
Outputs
OUTPUTS: Vibrio parahaemolyticus is the leading cause of human gastroenteritis associated with seafood consumption in the U.S. Numerous outbreaks of V. parahaemolyticus infection resulted from oyster consumption have been documented in the U.S. between 1997 and 2007. Several processes such as low temperature pasteurization, freezing, high pressure, and irradiation have been reported capable of reducing V. parahaemolyticus in oysters post harvest. However, the processes often kill oysters. Development of effective processing for reducing V. parahaemolyticus in oysters without significant adverse effects remains to be developed. Studies were conducted to investigate effects of temperature on depuration for reducing V. parahaemolyticus in Pacific (Crassostrea gigas) and Gulf (Crassostrea virginica) oysters. Shellstock oysters were inoculated with five-strain cocktail of V. parahaemolyticus and depurated in re-circulating artificial seawater at 15, 10, and 5 C for 48 h. Reductions of V.
parahaemolyticus in oysters were compared with those processed at ambient temperature. Studies were also conducted to determine effects of electrolyzed oxidizing (EO) water treatments on reducing histamine-producing bacteria (HPB) and histamine formation in fish. Scombroid poisoning is a common illness resulted from consuming fish containing histamine produced by activity of bacterial histidine decarboxylase. Enterobacter aerogenes and Morganella morganii are known to be the most prolific HPB and capable of producing >1,000 ppm histamine in fish exposed to elevated temperatures. Development of post-harvest treatments for reducing HPB in fish is an important step in preventing histamine formation in fish and reducing scombroid poisoning. These findings were disseminated at the 2007 IFT Conference.
PARTICIPANTS: Oregon State University Agricultural Research Foundation, National Fisheries Institute and National Sea Grant provided financial supports to this project. Dr. Dan Cheney of Pacific Shellfish Institute (Olympia, WA) was a collaborator for investigating effects of temperature on depuration for reducing V. parahaemolyticus in Pacific (Crassostrea gigas) and Gulf (Crassostrea virginica) oysters. This project provided training to two master graduate students of the Department of Food Science and Technology. Min Jung Chae was involved in the investigation of effects of temperature on depuration for reducing V. parahaemolyticus in Pacific (Crassostrea gigas) and Gulf (Crassostrea virginica) oysters. Sureerat Phuvasate was involved in investigation of electrolyzed oxidizing water treatments on reducing histamine-producing bacteria and histamine formation in fish.
TARGET AUDIENCES: Research findings were delivered to the seafood industry at Pacific HACCP Advisory Panel meetings, at OSU Surimi School lecture and laboratory training, and meetings with seafood industry.
Impacts
The U. S. produces more than 27 million pounds of oysters each year and most of them are sold and consumed raw without further processing. The U.S. Centers for Disease Control and Prevention estimates that 2,800 cases of V. parahaemolyticus illness associated with raw oyster consumption occur in the U.S. each year, which then usually results in reduced sale of oysters and a significant financial burden for the industries. The shellfish industries in the Pacific Northwest suffered from loss of millions of dollars in the summer of 2006 because of an unexpected V. parahaemolyticus outbreak. Low-temperature depuration appears to be a simple and inexpensive process for reducing V. parahaemolyticus contamination in Pacific oysters without adverse effects on the oysters. Depuration at ambient temperature (20-22 C) for 48 h resulted in about 1.0-log reduction of V. parahaemolyticus in both Pacific and Gulf oysters. Reducing depuration temperatures to 15, 10 and 5 C increased
the reductions of V. parahaemolyticus in Pacific oysters to 2.0-, 3.0- and >3.5-log MPN/g, respectively, after 48 h. However, reductions of V. parahaemolyticus in Gulf oysters reached maximal levels (about 1.0 log MPN/g) after 24 h at 15 and 10 C with only a slight reduction (0.4 log MPN/g) at 5 C after 24 h. The process can easily be adopted by the industry for producing raw oysters for safe consumption. Scombroid poisoning, caused by histamine intoxication, is one of the most prevalent illnesses associated with seafood consumption in the U.S. The illness is usually accompanied with a variety of symptoms, such as rash, nausea, diarrhea, flushing, sweating, and headache. Incidence of scombroid poisoning has been consistently reported in the U.S. through surveillance and is often underestimated due to mild and transient symptoms. The U.S. Food and Drug Administration seafood regulations limit histamine in fish at a level of 5 mg/100g (50 ppm) for assuring the safe consumption of fish.
This study found that E. aerogenes and M. morganii could survive well on food contact surfaces and fish skin. However, treatments of EO water (50 ppm chlorine) for 5 min completely inactivated the inoculated bacteria on food contact surfaces (>1.7 to >5.4 log CFU/cm2 reductions). Soaking salmon skin in EO water (100 ppm chlorine) for 120 min reduced E. aerogenes and M morganii by 1.3 and 2.2 log CFU/cm2, respectively. Holding fish skin in EO ice (100 ppm chlorine) for 24 h reduced E. aerogenes by 1.6 to 2.4 CFU/cm2 and M. morganii by 2.0 to 3.5 log CFU/cm2 on fish skin. Electrolyzed oxidizing water can be used as a sanitizer for decontaminating histamine-producing bacteria on food contact surfaces to prevent cross-contamination of fish with histamine-producing bacteria during processing. Holding fish in ice made from electrolyzed water could be used as a post-harvest treatment to reduce histamine-producing bacteria on fish skin and decrease probability of histamine formation in fish
during storage.
Publications
- Phuvasate P, Su Y-C. 2007. Evaluation of electrolyzed oxidizing water treatment for reducing histamine-producing bacteria on food contact surfaces and fish skin. Institute of Food Technologists Annual Meeting, July, Chicago.
- Su Y-C, Liu C, Hung Y-C. 2007. Electrolyzed Water: principles and applications. In: PC Zhu, ed. New Biocides Development: The Combined Approach of Chemistry and Microbiology. ACS Symposium Series No. 967, American Chemical Society, Washington, DC.
- Su Y-C, Liu C. 2007. Vibrio parahaemolyticus: a concern of seafood safety: a review. Food Microbiol. 24(6):549-558.
- Shen X, Lu J, Shu Y, Su Y-C, Liu C. 2007. Antibacterial effects of electrolyzed water against harmful bacteria in suspensions and on food processing surfaces. Microbiol. 34(3):90-93.
- Chiu T-C, Duan J, Su Y-C. 2007. Characteristics of virulent Vibrio parahaemolyticus isolated from Oregon and Washington. J Food Prot. 70:1011-1016.
- Lu J，Chen R，Shen X，Liu C，Su Y-C. 2007. Investigation of bacterial contamination status in retail oysters in Shanghai. Chin. J. Food Hygie. 19(1):18-20.
- Chen R, Lu J, Su Y-C, Liu C. 2007. Risk analysis, detection and control of Vibrio parahaemolyticus in foods. Food Sci. 28 (1):341-347.
- Chae M, Su Y-C. 2007. Temperature effects on depuration for reducing Vibrio parahaemolyticus and Vibrio vulnificus in Gulf oyster. Institute of Food Technologists Annual Meeting, July, Chicago.
- Yang Q, Su Y-C. 2007. Antimicrobial activity of wine components against Vibrio parahaemolyticus. Institute of Food Technologists Annual Meeting, July, Chicago.
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Progress 01/01/06 to 12/31/06
Outputs
Vibrio parahaemolyticus is the leading cause of human gastroenteritis associated with seafood consumption in the U.S. Understanding the incidence and characteristics of pathogenic V. parahaemolyticus in the marine environment as well as development of effective post-harvest processing for reducing V. parahaemolyticus contamination in oysters would provide valuable information for a better assessment of health risk associated with raw oyster consumption and reduce illness caused by the organism. Study was conducted to characterize 34 virulent strains of V. parahaemolyticus isolated from Oregon and Washington coastal water. Serological and molecular analyses of the isolates found that three Washington isolates exhibited identical serotype, virulence factors, and genotype to a strain causing 1997 Washington outbreak and nine Oregon isolates shared the same serotype, virulence factors, and genotype with a strain responsible for 1997 Oregon outbreak. Isolation of virulent
strains of V. parahaemolyticus identical to clinical strains involved in previous outbreaks indicates potential hazards associated with oyster consumption. This is evidenced by an unexpected V. parahaemolyticus outbreak occurred in the summer of 2006 in Oregon and Washington. Study was also conducted to determine bactericidal effects of wines against V. parahaemolyticus in oysters. Both red and white wines exhibited strong bactericidal activity again V. parahaemolyticus but were less effective in inactivating V. parahaemolyticus in whole oyster than in oyster meat homogenate. This finding suggests that wine consumption could be a potential natural means to inactivate V. parahaemolyticus in raw oysters and chewing oysters before swallowing might allow greater inactivation of V. parahaemolyticus if wine is consumed.
Impacts
The United States produces more than 27 million pounds of oysters each year and most of them are sold and consumed raw without further processing. It is estimated that 20 million Americans eat raw shellfish, making raw or undercooked shellfish the biggest seafood hazard. Occurrence of illness caused by consumption of contaminated raw oysters usually results in reduced sale of oysters, and a consequent significant financial burden for the industries. The shellfish industries in the Pacific Northwest suffered from loss of millions of dollars in the summer of 2006 because of an unexpected outbreak occurred in Oregon and Washington. This study provides evidence showing occurrence of pathogenic strains of V. parahaemolyticus in the environment may be persistent and could be used for risk assessment of V. parahaemolyticus infections associated with raw oyster consumption and reduce the illnesses associated with raw oyster consumption.
Publications
- Chiu T-C, Duan J, Liu C, Su Y-C. 2006. Efficacy of electrolyzed oxidizing water in inactivating Vibrio parahaemolyticus on kitchen cutting boards and food contact surfaces. Lett. Appl. Microbiol. 43: 666-672.
- Ren T, Su Y-C. 2006. Effects of electrolyzed oxidizing water on reducing Vibrio parahaemolyticus and Vibrio vulnificus in raw oysters. J. Food Prot. 69:1829-1834.
- Liu C, Chen R, Su Y-C. 2006. Bactericidal activity of wine against Vibrio parahaemolyticus in oysters. J. Food Prot. 69:1823-1828.
- Liu C, Su Y-C. 2006. Efficacy of electrolyzed oxidizing water on reducing Listeria monocytogenes contamination on seafood processing gloves. Int. J. Food Microbiol. 110:149-154.
- Duan J, Liu C, Su Y-C. 2006. Evaluation of a double layer agar plate for direct enumeration of Vibrio parahaemolyticus. J. Food Sci. 71:M77-82.
- Liu C, Duan J, Su Y-C. 2006. Effects of electrolyzed oxidizing water on reducing Listeria monocytogenes contamination on seafood processing surfaces. Int. J. Food Microbiol. 106:248-253.
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Progress 01/01/05 to 12/31/05
Outputs
Listeria monocytogenes is a foodborne pathogen that can cause serious diseases in humans. The cool and wet seafood-processing environment is conducive to the presence of L. monocytogenes. Cooked seafood, particularly shrimp, crab, and lobster that are usually picked by hand, can easily be contaminated with L. monocytogenes through poor sanitation or personal hygiene. The zero-tolerance policy adopted by the Food and Drug Administration for L. monocytogenes in ready-to-eat (RTE) foods represents a substantial challenge that must be met by RTE seafood producers. Reducing contamination of L. monocytogenes in seafood processing environments is a critical step to ensure safety of RTE seafood. Studies were conducted to determine the effects of electrolyzed oxidizing (EO) water on reducing L. monocytogenes contamination on seafood processing surfaces. Treatments of EO water significantly reduced populations of L. monocytogenes on clean surfaces of stainless steel, ceramic
tile, and floor tile by greater than 99.9%. Presence of food residue on processing surfaces reduced the efficacy of reduction. However, treatments of EO water still resulted in significant reductions of L. monocytogenes on surfaces of stainless steel and ceramic tile containing food residue by greater than 99%.
Impacts
The U.S. Department of Agriculture estimated that 2,500 cases of listeriosis occur in the U.S. each year, with nearly 2,300 hospitalizations and 500 deaths. Outbreaks of listeriosis caused by consumption of RTE seafood, including cold-smoked fish, smoked mussels, and imitation crabmeat, have been reported in several countries. Application of EO water as a sanitizer following a thorough cleaning process can greatly reduce L. monocytogenes contamination in seafood processing environments and minimize foodborne illness caused by consumption of RTE seafood.
Publications
- Duan J, Su Y-C. 2005. Comparison of a chromogenic medium with thiosulfate-citrate-bile salts-sucrose agar for detecting Vibrio parahaemolyticus. J. Food Sci. 70:M125-128.
- Su Y-C, Daeschel MA. Sanitation and HACCP. 2005. In: JW Park, ed. Surimi and Surimi Seafood, 2nd ed. Marcel Dekker, Inc., New York.
- Su Y-C, Daeschel MA, Frazier J, Jaczynski J. 2005. Microbiology and Pasteurization of Surimi Seafood. In: JW Park, ed. Surimi and Surimi Seafood, 2nd ed. Marcel Dekker, Inc., New York.
- Duan J, Su Y-C. 2005. Occurrence of Vibrio parahaemolyticus in Two Oregon Oyster-growing Bays. J. Food Sci. 70:M58-63.
- Su Y-C. 2005. Detection of Vibrio parahaemolyticus with a chromogenic medium. Symposium on Taiwan-America Agricultural Cooperative Projects (p.113-119), Taipei, Taiwan.
- Su Y-C, Duan J, Wu W-H. 2005. Selectivity and sensitivity of a chromogenic medium for detecting Vibrio parahaemolyticus. J. Food Prot. 68:1454-1456.
- Duan J, Su Y-C. Serological typing of pathogenic Vibrio parahaemolyticus isolated from Oregon and Washington costal water. International Association of Food Protection 2005 Annual Meeting (abstract #P5-50), Baltimore, MD.
- Duan J, Su Y-C. Detection of Vibrio parahaemolyticus with direct surface plating on thin agar layer plate. Institute of Food Technologists 2005 annual meeting (abstract #28894), New Orleans. LA.
- Su Y-C, Liu C. Effects of electrolyzed oxidizing water on reducing Listeria monocytogenes contamination of seafood processing gloves. Institute of Food Technologists 2005 annual meeting (abstract #29223), New Orleans. LA.
- Ren T, Su Y-C. Effects of electrolyzed oxidizing water on reducing bacterial contamination in raw oysters. Institute of Food Technologists 2005 annual meeting (abstract #29051), New Orleans.
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Progress 01/01/04 to 12/31/04
Outputs
The occurrence of Vibrio parahaemolyticus in shellfish, particularly oysters, is a seafood safety concern of the oyster industry and consumers. Sporadic illnesses of V. parahaemolyticus infections associated with raw oyster consumption continue to be reported in Oregon. However, limited information is available on the occurrence of pathogenic V. parahaemolyticus in Oregon oyster-growing environments. Studies were conducted at two Oregon oyster-growing areas (Yaquina and Tillamook Bays) over a one-year period to investigate the occurrence of pathogenic V. parahaemolyticus in the oyster-growing environments and provide needed information for assessment of microbial risks associated with raw oyster consumption. Vibrio parahaemolyticus was detected in 15.0% of oyster, 20.0% of seawater, and 47.5% of sediment samples with very low levels of pathogenic strains being detected in oysters (<3.6 MPN/g). The densities of total and pathogenic V. parahaemolyticus were higher in
sediment (<1,100 and <43 MPN/g) than in seawater (<15 and <3.6 MPN/100mL) or oyster (<43 and <3.6 MPN/g). Densities of V. parahaemolyticus in both bays were positively correlated to water temperatures with higher densities of the organism being detected in summer, especially July and August. There was no correlation between the densities of V. parahaemolyticus and water salinity or the densities of V. parahaemolyticus and bacterial populations in seawater. These results indicate that oysters produced at these two Oregon bays are less likely to cause V. parahaemolyticus infection when consumed. However, freshly harvested oysters, especially during summer, should be kept at refrigeration temperatures until consumption to prevent rapid growth of pathogenic V. parahaemolyticus in contaminated oysters.
Impacts
Raw or undercooked seafood are the main vehicles for Vibrio infections. It is estimated that 20 million Americans eat raw oysters, making raw or undercooked oysters the biggest seafood hazard in the United States. Consumption of raw and undercooked shellfish has been reported to account for more than 90% of 113,000 seafood-poisoning cases occurred in the U.S each year. Occurrence of illness caused by consumption of contaminated raw oysters usually results in reduced sale of oysters, and a consequent significant financial burden for the industries. Yearly costs of all foodborne diseases in the U.S. were estimated to be $5-6 billion dollars in direct medical expenses and loss of productivity. This study provides much needed information to assess microbial risks associated with Oregon oyster consumption.
Publications
- No publications reported this period
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Progress 01/01/03 to 12/31/03
Outputs
Acidified sodium chlorite and electron beam irradiation were studied for reducing bacterial contamination in seafoods. Washing salmon with acidified sodium chlorite (ASC) solution significantly (p<0.05) reduced total bacterial populations on skin and fillets as well as Listeria monocytogenes contamination on fillets. Treatment with acidified sodium chlorite also increased the shelf life of fresh salmon stored at refrigerating temperatures. The antimicrobial activity of ASC was enhanced when salmon was washed with ASC solution and stored in ASC ice. Acidified sodium chlorite can be used as a secondary direct food additive for increasing shelf life and safety of raw fish. For electron beam (e-beam) irradiation study, cold-smoked salmon fillets were inoculated with L. monocytogenes (4.4 x 103 CFU/g) and exposed to e-beam at doses of 1, 2, and 4 kGy. L. monocytogenes cells (3.6 log CFU/g) on inoculated salmon were reduced by 2.5 log CFU/g with a low e-beam dose of 1.0 kGy
and were completely eliminated by e-beam doses of 2.0 kGy and greater. E-beam irradiation was found to be effective in reducing bacterial contamination on cold-smoked salmon and could be used to increase safety of cold-smoked fish. This project will continue to investigate new technologies for reducing microbial contamination in seafoods, particularly Listeria monocytogenes in processing environments and ready-to-eat products.
Impacts
Foodborne outbreaks involving seafood consumption can be extremely costly to the economy, seafood industries, and consumers. Application of innovative technologies for improving quality and safety of seafood will increase values of seafoods and minimize microbial hazards associated with seafood consumption. Seafood industries and consumers will all benefit from the development of new technologies for seafood processing.
Publications
- Su, Y.-C., Duan, J., and Morrissey, M. T. 2003. Electron beam irradiation for reducing Listeria monocytogenes contamination on cold-smoked salmon. JAFPT (In Press).
- Su, Y.-C., and Morrissey, M. T. 2003. Reducing levels of Listeria monocytogenes contamination on raw salmon with acidified sodium chlorite. J. Food Prot. 66:812-818.
- Kim, S.-H., An, H., Wei, C.-I., Visessanguan, W., Benjakul, S., Morrissey, M. T., Su, Y.-C., and Pitta, T. P. 2003. Molecular detection of a histamine former, Morganella morganii, in albacore, mackerel, sardine, and a processing plant. J. Food Sci. 68:453-457.
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