<OL> <LI> To determine the effect of monolaurin on the growth and survival of Listeria monocytogenes on cooked ready-to-eat (RTE) shrimp stored under different atmospheric packaging conditions and storage temperatures. <LI> To quantify fillet quality and safety differences between aquacultured U.S. channel catfish and imported Vietnamese basa catfish. <LI> To evaluate multiple underutilized Gulf of Mexico fish species for suitability for value added seafood products.
NON-TECHNICAL SUMMARY: The overall goal of this project is to enhance the value of marine and freshwater seafood harvested, processed, and marketed in Mississippi and U.S. Gulf Coast region. Specific objectives are: 1) To determine the effect of monolaurin on the growth and survival of Listeria monocytogenes on cooked ready-to-eat (RTE) shrimp stored under different atmospheric packaging conditions and storage temperatures; 2) To quantify fillet quality and safety differences between aquacultured U.S. channel catfish and imported Vietnamese basa catfish; and 3) To evaluate multiple under-utilized Gulf of Mexico fish species for suitability for value added seafood products. These three scientific objectives are consistent with research and development goals outlined by the Joint Subcommittee on Aquaculture Strategic/Implementation Plan. Specifically the objectives address three of the six goals found in the plan. Improved understanding of factors that can be used to control food safety hazards in seafoods is a major continuing effort of this project. In addition, recent pressure on domestic producers by less expensive imports is currently creating severe economic pressures on U.S. goods. This project will generate impartial scientific data that may be useful in relieving these pressures on the domestic seafood industry. Finally, technology development will help the U.S. seafood industry utilize less exploited species and may be useful in improving fisheries sustainability.
APPROACH: The effect of monolaurin on growth and survival rates of L. monocytogenes on RTE shrimp stored in different atmospheres at different temperatures will be determined. Inoculated shrimp will be treated with monolaurin (0, 50, 100, 250, and 500 ppm) prior to packaging in air, vacuum, and 100% CO2 and stored at 3C, 7C, and 12C for fifteen days. Non-inoculated control samples as well as inoculated samples will be plated at 3-day intervals beginning with day 0 and ending with day 15. Upon completion of counting, growth and survival characteristics of L. monocytogenes will be determined. U.S. aquacultured channel catfish and Vietnamese basa catfish will be analyzed for microbial quality and safety, sensory profiles, and proximate composition. Pathogen screen will include testing for the presence of Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, Vibrios spp., and Salmonella spp. Sensory analysis will be used to evaluate the sample flavor, odor, texture, and appearance as quality attributes. Proximate analysis will be used to identify and evaluate the differences in the chemical constituents of the two fish. Fish samples will be either fresh or frozen fillets obtained from retail outlets, food service establishments, and distributors. Chub mackerel, other species of herring, and other abundant Gulf of Mexico fish species (hard head catfish, menhaden, mullet, etc) will be evaluated for flesh quality and processing yields during four different seasons. For mechanical processing, about 500 lb of various fish species will be deheaded, gutted, deboned and skinned. Fresh mince produced from filleted fish will be subdivided into sub-samples for each treatment. During the wash cycle, the effect of pH variability on flesh color and texture will be evaluated. The addition of cryoprotectants will be evaluated for texture and gelling qualities. Analysis of processed minces will consist of proximate composition, biogenic amine profile, fatty acid composition, and sensory parameters. A variety of value added products will be explored to include fish hotdogs, smoked fish, imitation crab meat, etc. Each value-added product will be subjected to quality analysis including shelflife and consumer acceptability.
PROGRESS: 2003/09 TO 2006/09<BR>
The overall goal of this project was to enhance the value of marine and freshwater seafoods harvested, processed, and marketed in Mississippi and U.S. Gulf Coast region. During this project, several significant contributions were published. Several review articles and book chapters were published on catfish processing, aquaculture best practices, and antimicrobial agents. Research results indicated that the incidence of Listeria monocytogenes on catfish fillets is greater on fish taken from retail display compared to fish taken from processing lines. This work further demonstrated a low correlation between the incidence of Listeria and L. monocytogenes on processing plant fillets. Ready-to-eat shrimp taken from retail packages were determined to harbor a number of different foodborne pathogens, many of which were resistant to antibiotics commonly used to treat infections. A new rapid capacitance method to determine the microbial population on raw shrimp was described. The microbiological profile of basa was determined and was similar to profiles found with domestic catfish products. Because of hurricane Katrina, our seafood processing pilot plant in Pascagoula, MS was destroyed. This had a negative impact on our ability to conduct value added seafood processing work as originally proposed. Filleted bait fish (ground mullet, red herring, etc.) can be minced, washed and dried to a fish protein base that is free of undesirable off flavors from fish oil and fat. This fish protein base can then be flavored and textured for use in recipes much like you would use ground beef or crab meat. Consumer panels have evaluated products including fish cakes, meat balls and stuffed sausage with positive results (70-80% approval) and often times consumers thought they were eating crab products.
IMPACT: 2003/09 TO 2006/09<BR>
Improved understanding of factors that can be used to control food safety hazards in seafoods was a major effort of this project. The poor correlation of Listeria incidence and L. monocytogenes incidence on processing plant catfish fillets suggests that the routine use of Listeria testing is a poor method for assessing whether L. monocytogenes is under control in catfish processing plants. We recommended to catfish processors that testing directly for L. monocytogenes is a better method for verification than testing for Listeria. The widespread occurrence of pathogens on ready-to-eat shrimp was unexpected. This finding suggests that this industry should consider incorporating additional antimicrobial treatments during processing to eliminate pathogens as this product is marketed with instructions to simply thaw and eat. The new capacitance method to determine the microbiological quality of raw shrimp took less than half the time needed than when using the conventional method. Processors can thus release acceptable product into commerce more rapidly than when relying on traditional methods. Underutilized Gulf Coast bait fish can be processed into edible products for human consumption.