Rapid inactivation of Toxoplasma gondii bradyzoites in dry cured sausage

Authors: Hill, Dolores; Luchansky, John; Porto-Fett, Anna; GAMBLE, H.R. - National Academy Of Science; Urban, Joseph; Fournet, Valsin; Hawkins Cooper, Diane; GAJADHAR, A.A. - Canadian Food Inspection Agency; HOLLEY, R. - University Of Manitoba; Juneja, Vijay; Dubey, Jitender

Submitted to: Food and Waterborne Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/30/2018
Publication Date: 8/24/2018
Citation: Hill, D.E., Luchansky, J.B., Porto Fett, A.C., Gamble, H., Urban Jr, J.F., Fournet, V.M., Hawkins Cooper, D.S., Gajadhar, A., Holley, R., Juneja, V.K., Dubey, J.P. 2018. Rapid inactivation of Toxoplasma gondii bradyzoites in dry cured sausage. Food and Waterborne Parasitology. https://doi.org/10.1016/j.fawpar.2018.e00029.
DOI: https://doi.org/10.1016/j.fawpar.2018.e00029

Interpretive Summary: Curing is a preservation process that is widely used in the pork industry. Curing processes are developed to meet certain product characteristics, including increased shelf life and palatability/taste. There are many processed pork products that rely on a form of curing (pepperoni, salami, prosciutto, etc.). No control guidelines exist for inactivation of parasites such as Toxoplasma gondii that may reside within pork meat. In this study, we have assessed inactivation of Toxoplasma bradyzoites in pork meat used for preparation of dry cured sausage, using five parameters of meat chemistry: salt/brine concentration, aw, pH, temperature, and time. The objective of this study was to develop de novo inactivation data for pork curing processes which could be used to determine the effect of dry curing treatments on Toxoplasma bradyzoites in pork meat, based on meat chemistry of the final cured product. Using the newly developed inactivation data, existing and newly developed curing process that fall within the tested parameters can be assessed for risk mitigation with respect to Toxoplasma based on the meat chemistry of the final product.

Technical Abstract: Toxoplasma gondii is an intracellular parasite, infecting one-third of the world's population. Toxoplasma infection in humans can result in acute clinical disease and chronic conditions that markedly limit normal development and significantly impact quality of life. Exposure to the parasite via food is one important transmission route, since the bradyzoite stage of the parasite, contained within intracellular cysts, can be present in the meat of food animals, including pork. Curing process have been used for centuries to preserve meat products and limit microbial activity. Common dry curing process used today for the preparation of ready-to-eat meats have not been sufficiently evaluated for inactivation of Toxoplasma bradyzoites contained in the source meat used for these products. In this study, we have tested five variables monitored during curing- salt/brine concentration, water activity (aw), pH, temperature, and time, that represent the typical range of variables for dry cured pork sausage, using low and high endpoints for common curing treatments. These data demonstrated that inactivation of bradyzoites occured during the fermentation process. No viable Toxoplasma was isolated from any meat sample by mouse bioassay after fermentation; the time period between batter preparation and the first sample taken after fermentation was 24 hours. These data suggest that the fermentation methods used here were effective at inactivating Toxoplasma bradyzoites and can be used within the defined upper and lower endpoint parameters defined here to reduce or eliminate the need for individual product validation for Toxoplasma inactivation in RTE pork.