Elliot Ryser

Elliot Ryser

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Department of Food Science and Human Nutrition




PhD, University of Wisconsin, 1990
BS, University of Wisconsin, 1982

Professional Positions

Research Associate - Department of Animal and Food Sciences, University of Vermont, Burlington, VT.  March 1994 - January 1998

Research Project Manager - Silliker Laboratories Group, Inc., Chicago Heights, IL.  February 1992 - December 1993.

Research Scientist - Institute National de la Recherche Agronomique, Station de la Recherches Laitieres. Jouy-en-Josas, France.   February - March 1990, August 1990 - August 1991. 

Research Interests

Please note: In anticipation of his retirement in August 2022, Dr. Ryser is no longer accepting graduate students.

Quantitative transfer of Escherichia coli O157:H7, Salmonella and Listeria monocytogenes during production of fresh-cut fruits and vegetables including lettuce, tomatoes, cantaloupe, celery and onions; sanitizer efficacy during washing of fresh produce as influenced by organic load in the wash water; pathogen growth/survival in fresh-cut produce during commercial transport, retail storage and display as influenced by the type of packaging; cross-contamination of deli meats with Listeria monocytogenes during mechanical slicing; incidence of Listeria in retail deli meats; persistence of Listeria in biofilms; pathogen inactivation using X-ray irradiation; pathogen migration and thermal resistance in marinated whole-muscle meat and poultry products; optimizing the design and operation of commercial cooking systems for ready-to-eat meat and poultry products; thermal inactivation of sublethally injured Salmonella in fresh meats and low moisture foods; pathogen contamination and microbial diversity in poultry processing facilities; microbiological standards for blueberries; development of edible antibacterial films and casings from whey protein;  reduction of Listeria, Salmonella and E. coli O157:H7 on alfalfa sprouts, lettuce, cantaloupe, berries and apples using chlorine dioxide gas and various sanitizers; microbial safety and quality of fermented and non-fermented dairy products.

Instructional Activities

FSC 342 – Food Safety and HACCP
FSC 842 – Foodborne Diseases

Outreach Focus

Scientific Editor - Journal of Food Protection: 2006 - present

Editorial Board - Journal of Food Protection: 1993 - present

International Association for Food Protection: 1980 - present

Maurice Weber Laboratorian Award – 2011
President’s Recognition Award – 2011
Fellow Award – 2010
Elmer Marth Educator Award – 2007

Institute of Food Technologists: 1981 – present

Fellow Award - 2011
Scientific Editor: Journal of Food Science - Food Microbiology and Food Safety:  2000 - 2005   

Ad-hoc journal reviews: over 30 leading journals

Ad-hoc grant reviews and panels: USDA, FDA, NIH and various international agencies

Selected Publications


Ryser, E.T., and E.H. Marth (eds.). 2007. Listeria, Listeriosis and Food Safety, 3rd ed., Taylor & Francis, Boca Raton, FL.

Book Chapters

Wesche, A., Gurtler, J.B. and E.T. Ryser.  2012.  Stress adaptation and survival of foodborne pathogens. In Guide to Foodborne Pathogens, John Wiley & Sons (submitted).

Ryser, E.T., and J. Schuman. 2012. Aerobic plate count. In Compendium of Method for the Microbiological Examination of Foods, 5th Edition. American Public Health Assoc., Washington, DC (submitted).

Ryser, E.T., and C.W. Donnelly. 2012. Listeria. In Compendium of Method for the Microbiological Examination of Foods, 5th Edition. American Public Health Assoc., Washington, DC (submitted).

Ryser. E.T. and R.L Buchanan. 2012. Listeria monocytogenes. In Food Microbiology – Fundamentals and Frontiers, 4th Edition. ASM Press, Washington, DC (submitted).

Ryser, E.T. 2011. Safety of dairy products. In Microbial Food Safety – An Introduction, pp. 127-145. O. Oyarzabal and S. Backert (eds.). Springer, New York.

Ryser, E.T. 2011. Pathogens in milk: Listeria monocytogenes, pp. 1650-1655.  In: Encyclopedia of Dairy Sciences, 2nd Edition.  Roginski, H., P.F. Fox and J.W. Fuqyay (eds.).  Academic Press, London.

Ryser, E.T. 2011. Pasteurisation of liquid milk products: Principles, public health aspects, pp. 2232-2237. In: Encyclopedia of Dairy Sciences, 2nd Edition.  Roginski, H., P.F. Fox and J.W. Fuqyay (eds.).  Academic Press, London.

Buchholz, A.L., G.R. Davidson, and E.T. Ryser. 2011. Microbiology of fresh and processed vegetables, pp. 159-182. In: Handbook of Vegetables and Vegetable Processing. Sinha, N.K., and Y.H. Yui (eds.). Wiley-Blackwell, Ames, IA.

Behling, R.G., J. Eifert, M.C. Erickson, J.B. Gurtler, J.L. Kornacki, E. Line, R. Radcliff, E.T. Ryser, B. Stawick, and Z. Yan. 2010. Selected pathogens of concern to industrial food processors: Infections, toxigenic, toxico-infections, selected emerging pathogenic bacteria, pp. 5-61. In Principles of Microbiological Troubleshooting in the Industrial Food Processing Environment, J.L. Kornacki (ed.), Springer, New York.

Ryser, E.T. 2009. Listeria monocytogenes, pp. 143-144.  In Biosafety in Microbiological and Biochemical Laboratories, 5th edition. U.S. Department of Health and Human Services – Public Health service, Centers for Disease Control and Prevention and the National Institutes of Health, U.S Government Printing Office, Washington, DC.

Ryser, E.T, Z. Yan, and J. Hao. 2009.  Attachment and internalization of pathogens in produce, 55-80. In: Microbial Safety of Fresh Produce, Fan, X., B.A. Niemira, C.J. Doona, F.E. Feeherry, and R.B. Gravani (eds.). Wiley-Blackwell, Ames, IA.

Peer-Reviewed Publications

M. I. Tenorio-Bernal, M.I., B. P. Marks, E. T. Ryser, and A. M. Booren. 2013. Evaluating the predictive ability of a path-dependent thermal inactivation model for Salmonella subjected to prior sublethal heating in ground turkey, beef, and pork. J. Food Prot. 76: (in press).

Buchholz, A.L., G.R. Davidson, B.P. Marks, E.C.D. Todd, and E.T. Ryser. 2012. Transfer of Escherichia coli O157:H7 from equipment surfaces to fresh-cut leafy greens during processing in a model pilot-plant production line with sanitizer-free water. J. Food Prot. 75:1920-1929.

Buchholz, A.L., G.R. Davidson, B.P. Marks, E.C.D. Todd, and E.T. Ryser. 2012. Quantitative transfer of Escherichia coli O157:H7 to equipment during small-scale production of fresh-cut leafy greens. J. Food Prot. 75:1184-1197.

Zhang, L., S.R. Moosekian, E.C.D. Todd, and E.T. Ryser. 2012. Growth of Listeria monocytogenes in different retail delicatessen meats during simulated home storage. J. Food Prot. 75:896-905.

Moosekian, S.R., S. Jeong, B.P. Marks, and E.T. Ryser. 2012. X-ray irradiation as a microbial intervention strategy for food. Ann. Rev. Food Sci. Technol. 3:493-510.

Jeong, S., B.P. Marks, J. Harte and E.T. Ryser. 2012. The effect of X-ray irradiation on Salmonella inactivation and sensory quality of almonds and walnuts as a function of water activity. Int. J. Food Microbiol. 153:365-371.

Zhang, L., J.Y. Jeong, K.K. Kishorekumar, E.T. Ryser and I. Kang. 2011. Microbiological quality of water-immersion and air-chilled broilers. J. Food Prot. 74:1531-1535.

Jeong, S., B.P. Marks, and E.T. Ryser. 2011. Quantifying the performance of Pediococcus sp. (NRRL B-2354: Enterococcus faecium) as a nonpathogenic surrogate for Salmonella Enteritidis PT30 during moist-air convection heating of almonds. J. Food Prot. 74:603-609.

Pérez Rodríguez, F.,  D. Campos, E.T. Ryser, A.M. Buchholz, B.P. Marks, Z, Gonzalo, and E.C.D. Todd. 2011. A mathematical risk model for Escherichia coli O157:H7 cross-contamination of lettuce during processing. Food Microbiol. 28:694-701.

Jeong, S., S.R. Moosekian, B.P. Marks, and E.T. Ryser. 2010. Inactivation of Escherichia coli O157:H7 on lettuce using low-energy x-ray irradiation. J. Food Prot. 73:547-551. 

Shin, J., S. Selke, E.T. Ryser, and B. Harte. 2010. Active packaging of fresh chicken breast, with ally isothiocyanate (AITC) in combination with modified atmosphere packaging (MAP) to control the growth of pathogens. J. Food Sci. 75:M65-M71.

Velasquez, A., T.J. Breslin, B.P. Marks, A. Orta-Ramirez, N.O. Hall, A.M. Booren, and E.T. Ryser. 2009. Enhanced thermal resistance of Salmonella in marinated whole muscle as compared to ground pork. J. Food Prot. 73-372-375.

Mogollón, M.A., B.P. Marks, A.M. Booren, A, Orta-Ramirez, and E.T. Ryser. 2009. Effect of beef product structure on Salmonella thermal inactivation. J. Food Sci. 74: M347-351.

Wesche, A.M., J. Gurtler, B.P. Marks, and E.T. Ryser.  2009. Inactivation of sublethally injured bacterial pathogens in foods - A review.  J. Food Prot. 72:1121-1138.

Tuntivanich, V., A. Velasquez, A. Orta-Ramirez, E.T. Ryser, B.P. Marks, and A.M. Booren. 2008. Thermal inactivation of Salmonella in whole muscle and ground turkey breast. J. Food Prot. 71:2548-2551.

Keskinen, L.A., E.C.D. Todd, and E.T. Ryser. 2008. Impact of bacterial stress and biofilm formation on Listeria monocytogenes transfer during slicing of deli meats.  Int. J. Food Microbiol. 127:298-304.

Moorman, M., C. Thelemann, J. Pestka, J. Linz and E.T. Ryser. 2008.  Altered hydrophobicity and membrane composition in stress-adapted Listeria innocua. J. Food Prot. 71:182-185.

Keskinen, L.A., E.C.D. Todd, and E.T. Ryser. 2008. Transfer of surface-dried Listeria monocytogenes from stainless steel knife blades to roast turkey breast. J. Food Prot. 71:176-181.

Warsow, C.R., A. Orta-Ramirez, B.P. Marks, E.T. Ryser, and A.M. Booren.  2008. Single directional migration of Salmonella spp. into marinated whole muscle turkey breast. J. Food Prot. 71:153-156.