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United States Department of Agriculture

Agricultural Research Service

Related Topics

Research Project: Umbrella Project for Food Safety

Location: Warmwater Aquaculture Research Unit

2008 Annual Report


1a.Objectives (from AD-416)
Research will address methods to determine the presence of pathogens in catfish/catfish products and to maximize elimination methods. Detection techniques will be developed to aid in processing and packaging operations, which should further enhance product safety. Specifically the new objectives are: 1)Optimize safety of aquaculture products through innovative processes for reducing microbiological, physical and chemical hazards in seafood/aquaculture products. 2)Determine the mechanisms influencing microbial survival of selected pathogens in seafood/aquaculture products. 3)Optimize the market value of seafood/aquaculture products through enhanced food safety and quality.


1b.Approach (from AD-416)
These funds will be used for.
1)Extramural research with Mississippi Center for Food Safety and.
2)Aflatoxin research. Original start and term dates 5/14/93-5/13/98, then 05/14/98 - 05/13/03, then 05/14/03 - 05/13/08.


3.Progress Report
Research related to control of pathogens in food products, in particular Listeria monocytogenes, is focused on developing strategies for reducing L. monocytogenes in catfish, seafood, and other meat products. New generally regarded as safe (GRAS) antimicrobials for control of bacterial pathogens in ready-to-eat products are being developed and tested for their effectiveness. Studies on the genetic and environmental determinants of virulence of L. monocytogenes have demonstrated that both genotype and environment play a role in the virulence of this important food pathogen. This information will be critical in developing tests and protocols required to control L. monocytogenes in catfish, seafood, and other meat products. A rapid, inexpensive antibody-based assay is being developed for detecting botulism neurotoxin. This assay will be useful for screening purposes. A luciferase reporter gene has been inserted into Salmonella enterica and selectively produces light in viable cells. This technique allows real-time detection of the bacteria at low levels and allows monitoring of bacterial progression under different environmental and chemical conditions. Bacteria numbers and bioluminescence correlated well in all strains. These research projects will play a role in assuring safe, high-quality food products to consumers and will be important to maintaining viable aquaculture and seafood industries in the U.S.

Publications

Attila Karsi, Kevin Howe, Tasha B. Kirkpatrick, Robert W. Wills, R. Hartford Bailey, and Mark L. Lawrence. 2008. Development of bioluminescent Salmonella strains for use in food safety. BioMed Central-Microbiology 2008, 8:10.

Battula, V., Schilling, M.W., Vizzier-Thaxton, Y., Behrends, J.B., Williams, J.B., Schmidt, T.B. 2008. The effects of low atmosphere stunning and deboning time on broiler breast meat quality. Poultry Science. 87:1202-1210. Bohoua, G. L. and Haque, Z.U. 2007. Surface activity of surfactants and dairy proteins. Milchwissenschaft. 62(4):394-397.

Chen, B.Y., Kim, T.J., Jung, Y.S. and Silva, J.L. 2008. Attachment strength of Listeria monocytogenes and its internalin negative mutants. Food Biophysics (Accepted 5-08, # FOBI120R1, Available online: http://www.springerlink.com/content/j21464621762nxu1/).


4.Accomplishments
1. New GRAS Bacteriophage LISTEXTM P100 for Quantitative Reduction of Listeria monocytogenes Loads in Aquaculture Products/Seafood Products.

New classes of GRAS (generally recognized as safe) antimicrobials are in strong demand for improving mitigation strategies against L. monocytogenes in various ready-to-eat food products. Food and Drug Administration (FDA) has recently approved two lytic bacteriophage preparations as GRAS for food safety of ready-to-eat food products against L. monocytogenes. Currently, there is a limited knowledge on how various food-associated factors influence Listeria bacteriophage efficacy in food products. New experimental models have been constructed for the determination of GRAS Listex P100 phage efficacy against L. monocytogenes from aquaculture products and seafood products. This research will provide potential methods for controlling listeria in ready-to-eat products.

This research supports NP 108 – Food Safety, Component 1.2 – Pathogens, Toxins and Chemical Contaminansts – Postharvest; Problem Statements 1.2.4 Processing Intervention Strategies and 1.2.6 Safety and Health.

2. Innovative processing effects on safety and quality of muscle foods.

In our food safety research projects, we have been able to detect changes in the composition of flavor compounds and sensory quality of food products due to irradiation, pest prevention practices, animal harvesting methods, and product processing. It was determined that irradiation of ground beef and fumigation of hams with sulfuryl fluoride did not negatively impact sensory quality or safety of consuming these products. Catfish fillets were enhanced via vacuum tumbling with salt (0.50%) and various phosphate products (0.45%) to determine their impact on product quality and shelf-life. It was determined that enhancement with phosphate and salt did not affect the shelf-life of the product and these methods were as effective as more expensive phosphate blends. We found that the use of phosphates increased yields and tenderness of catfish fillets without affecting shelf-life, odor, or color when compared to non-marinated catfish fillets.

This research supports NP 108 – Food Safety, Component 1.2 – Pathogens, Toxins and Chemical Contaminansts – Postharvest; Problem Statements 1.2.4 Processing Intervention Strategies and 1.2.6 Safety and Health and NP 106- Aquaculture; Component 9 Quality, Safety, and Variety of Aquaculture Products for Consumers.

3. Innovative processing effects on safety and quality of muscle foods.

In our food safety research projects, we have been able to detect changes in the composition of flavor compounds and sensory quality of food products due to irradiation, pest prevention practices, animal harvesting methods, and product processing. It was determined that irradiation of ground beef and fumigation of hams with sulfuryl fluoride did not negatively impact sensory quality or safety of consuming these products. Catfish fillets were enhanced via vacuum tumbling with salt (0.50%) and various phosphate products (0.45%) to determine their impact on product quality and shelf-life. It was determined that enhancement with phosphate and salt did not affect the shelf-life of the product and these methods were as effective as more expensive phosphate blends. We found that the use of phosphates increased yields and tenderness of catfish fillets without affecting shelf-life, odor, or color when compared to non-marinated catfish fillets.

This research supports NP 108 – Food Safety, Component 1.2 – Pathogens, Toxins and Chemical Contaminansts – Postharvest; Problem Statements 1.2.4 Processing Intervention Strategies and 1.2.6 Safety and Health and NP 106- Aquaculture; Component 9 Quality, Safety, and Variety of Aquaculture Products for Consumers.

4. A global analysis of meat matrix-mediated gene expression in Listeria monocytogenes.

Recently, several foodborne outbreaks have been related to the consumption of L. monocytogenes contaminated ready-to-eat (RTE) meat products particularly sliced turkey meat. A number of studies have suggested that environmental conditions can alter bacterial protein expression and potential for disease. However, little is known about whether the growth of L. monocytogenes on a RTE meat matrix has an impact on the bacterium’s ability to cause disease. We identified 77 proteins uniquely expressed by turkey meat-grown L. monocytogenes, including proteins known to be involved in virulence and stress adaptation. Our results suggest that certain proteins that are expressed by RTE meat-grown L. monocytogenes may contribute to the virulence of the bacterium.

This research supports NP 108 – Food Safety, Component 1.2 – Pathogens, Toxins and Chemical Contaminansts – Postharvest; Problem Statements 1.2.4 Processing Intervention Strategies and 1.2.6 Safety and Health.

5. Channel Catfish Immune recognition of Botulism Neurotoxin E.

Identification of regions recognized by antibodies for any given protein provides the foundation for new vaccine design and diagnostics. We proposed the development of a sensitive, low cost, toxin-free assay Enzyme-Linked Immunosorbent Assay (ELISA) as a tool for assessing channel catfish toxin specific antibody production. We screened binding with a panel of 69 synthetic toxin peptides from archived channel catfish sera from catfish exhibiting symptoms of visceral toxicosis of catfish (VTC), non exposed specific pathogen free fish, and fish previously exposed or immunized with unrelated antigens. Due to the amount of antibody cross reactivity demonstrated thus far, we are still in the process of defining the optimal parameters for the assay. When refined, this assay will be useful for screening purposes.

This research supports NP 108 – Food Safety, Component 1.2 – Pathogens, Toxins and Chemical Contaminansts – Postharvest; Problem Statements 1.2.4 Processing Intervention Strategies and 1.2.6 Safety and Health.

6. Efficacy of native and thermized sweet and sour whey as antioxidative and antibacterial coating agents to extend shelf-life and quality of catfish and red meat products.

Extending shelf-life while maintaining quality is an important issue for catfish sold fresh. Edam whey was manufactured in large batches (50 gal) using a standard method and separated to remove residual fat at the MSU Dairy Plant. The whey was then thermized using different temperatures/time protocols, concentrated to about 25% (w/v) solids using a Vacuum Evaporator (~70°C) and spray dried. Experiments were also carried out to observe the effect of thermization on enhancements of antioxidative capacity of casein hydrolyzates (found in whey) and data were presented at the 2008 Annual meeting of the Institute of Food Technologists. Data clearly showed that thermization enhanced total radical-trapping potential. This research could lead to methods to increase shelf-life and quality of catfish fillets.

This research supports NP 108 – Food Safety, Component 1.2 – Pathogens, Toxins and Chemical Contaminansts – Postharvest; Problem Statements 1.2.4 Processing Intervention Strategies and 1.2.6 Safety and Health and NP 106- Aquaculture; Component 9 Quality, Safety, and Variety of Aquaculture Products for Consumers.

7. Genetic Basis for Variation of Virulence Factor Expression in Listeria monocytogenes.

Listeria monocytogenes is an important foodborne pathogen that is of concern because of its frequent isolation from ready-to-eat food products, including aquaculture products. Interestingly, L. monocytogenes strains demonstrate varied pathogenic potential. We have demonstrated that many L. monocytogenes isolates from channel catfish are nonpathogenic, and we have identified genes that can be used to distinguish pathogenic and nonpathogenic isolates. Our objective is to determine if genetic differences previously identified in internalin genes between pathogenic and nonpathogenic L. monocytogenes isolates are causitive for differences in pathogenecity. Current research is focused on determining if these genes are causative for viulence in L. monocytogenes. Determination of genes influencing pathogenicity of this important food pathogen will be useful for detecting and controlling pathogenic strains of L. monocytogenes.

This research directly addresses National Program 108 – Food Safety, Component 1.2 – Pathogens, Toxins and Chemical Contaminansts – Postharvest; Problem Statements 1.2.5 Omics, 1.2.6 Safety and Health, and 1.2.8 Pathogenecity.

8. Surface Protein Interaction of Listeria responsible for attachment strength.

We have demonstrated certain proteins from L. monocytogenes, InlA and InlB, are responsible for the attachment of L. monocytogenes to food contact surfaces. It was also found that L. monocytogenes has stronger attachment strength than other human pathogens. It has been shown so far that certain processes and sources yield components with high antimicrobial activity. Some of these are Muscadine seeds, red Muscadine components, and certain blueberry products subjected to certain processes.

This research directly addresses National Program 108 – Food Safety, Component 1.2 – Pathogens, Toxins and Chemical Contaminansts – Postharvest; Problem Statements 1.2.5 Omics, 1.2.6 Safety and Health, and 1.2.8 Pathogenecity.

9. Development of Real-time Bioluminescent Assays for Investigating Salmonella, Campylobacter and E. coli in Foods of Animal Origins.

The Mississippi broiler and catfish industries are vital to the state economy of Mississippi. Our goal is to help the food animal industry meet federal food safety regulations by developing in vitro real-time models for studying three organisms (Salmonella, E. coli, and Campylobacter) commonly associated with human disease from foods of animal origin. We have developed methods using wild-type Salmonella enterica strains with an inserted light-producing gene (lux) for real-time detection and tracking of bacteria. These luminescent bacteria are detectable at low levels, can be monitored real-time, and bacteria numbers and bioluminescence are strongly correlated. Ultimately, this novel laboratory technique will also be useful in the study of different processing steps relative to their effect on the viability, presence and control of Salmonella, E. coli and Campylobacter on products of animal origin.

This research supports NP 108 – Food Safety, Component 1.2 – Pathogens, Toxins and Chemical Contaminansts – Postharvest; Problem Statements 1.2.4 Processing Intervention Strategies and 1.2.6 Safety and Health and NP 106- Aquaculture; Component 9 Quality, Safety, and Variety of Aquaculture Products for Consumers.


5.Significant Activities that Support Special Target Populations
Assuring safety and improving quality of domestic farm-raised catfish will benefit operators of small farms by expanding markets for catfish products. The USDA Census of Aquaculture in 2000 classified 84% of catfish farms as small businesses, with annual sales of less than $500,000. Of the 1,370 catfish farms in the United States, 515 farms (38% of the total) reported annual revenues of less than $25,000. Expansion of markets through development safe, high quality domestic catfish products will benefit U.S. catfish farmers, a significant portion of which are classified as small farmers.


6.Technology Transfer

Number of Non-Peer Reviewed Presentations and Proceedings8

Review Publications
Battula, V., Schilling, M.W., Vizzier-Thaxton, Y., Behrends, J.B., Williams, J.B., Schmidt, T.B. 2008. The Effects of Low Atmosphere Stunning and Deboning Time on Broiler Breast Meat Quality. Poultry Science. 87:1202-1210.

Gandy, A.E., Schilling, M.W., Coggins, P.C., White, C.W., Yoon, Y., Kamadia, V.V. 2008. The Effect of Pasteurization Temperature on Consumer Acceptability, Sensory Characteristics, Volatile Compound Composition, and Shelf-Life of Fluid Milk. Journal of Dairy Science. 91:1769-1777.

Kim, T.Y., Jung, S., Silva, J.L., Danviriyakul, S. 2007. Detection and Rapid Purification of Internalin B as A Protein Marker in Listeria monocytogenes. Food Biotechnology. 21:161-168.

Kim, T., Weng, W.L., Stojanovic, J., Lu, Y., Jung, Y.S., Silva, J.L. 2008. Antimicrobial Effect of Water-Soluble Muscadine Seed Extracts on Escherichia coli O157:H7. Journal of Food Protection. 71:1465-1468.

Liu, D., Lawrence, M.L., Ainsworth, A.J. 2008. A Novel PCR Assay for Listeria welshimeri Targeting Transcriptional Regulator Gene lwe1801. Journal of Rapid Methods and Automation in Microbiology. 16:152-161.

Liu, D., Lawrence, M.L., Austin, F.W., Ainsworth, A.J. 2007. A Multiplex PCR for Species- and Virulence-specific Determination of Listeria monocytogenes. Journal of Microbiological Methods. 71(2):133-140.

Liu, D., Lawrence, M.L., Ainsworth, A.J., Austin, F.W. 2007. Toward an Improved Laboratory Definition of Listeria monocytogenes Virulence. International Journal of Food Microbiology. 118(2):101-15.

Liu, D., Lawrence, M.L., Pinchuk, L.M., Ainsworth, A.J., Austin, F.W. 2007. Characteristics of Cell-mediated, Anti-listerial Immunity Induced by A Naturally Avirulent Listeria monocytogenes Serotype 4a Strain HCC23. Archives Of Microbiology. 188(3):251-6.

Liu, D. 2008. Epidemiology. In Liu, D. (ed) Handbook of Listeria monocytogenes, Pages 27-59. CRC Press, Florida.

Liu, D., Lawrence, M.L., Ainsworth, A.J., Austin, F.W. 2008. Genotypic Identification. In Liu, D. (ed) Handbook of Listeria monocytogenes, Pages 169-201. CRC Press, Florida.

Roche, S.M., Velge, P., Liu, D. 2008. Virulence Determination. In Liu, D. (ed) Handbook of Listeria monocytogenes, Pages 241-270. CRC Press, Florida.

Liu, D. (ed). 2008. Handbook of Listeria monocytogenes. CRC Press, Boca Raton, Florida.

Mujihid, S., Pechan, T., Wang, C. 2007. Improved Solubilization of Surface Proteins from Listeria monocytogenes for Two-dimensional Gel Electrophoresis. Electrophoresis. 28:3998-4007.

Pham, A.J., Schilling, M.W., Yoon, Y., Kamadia, V.V., Marshall, D.L. 2008. Characterization of Fish Sauce Aroma Impact Compounds Using GC-MS, SPME-Osme-GCO, and Stevens' Power Law Exponents. Journal of Food Science. 73(4):C268-C274.

Attila, K., Howe, K., Kirkpatrick, T.B., Wills, R.W., Hartford-Bailey, R., Lawrence, M.L. 2008. Development of Bioluminescent Salmonella Strains for Use in Food Safety. BioMed Central-Microbiology. 8:10.

Chen, B.Y., Kim, T.J., Jung, Y.S., Silva, J.L. 2008. Attachment Strength of Listeria monocytogenes and Its Internalin Negative Mutants. Food Biophysics. 3:329-332.

Last Modified: 8/19/2014
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