Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 10, 2006
Publication Date: September 1, 2006
Citation: Hill, D.E., Benedetto, S.M., Coss, C., Mccrary, J.L., Fournet, V.M., Dubey, J.P. 2006. Time and temperature effects on T. gondii tissue cysts in enhanced meats; the effect of time and temperature on the viability of Toxoplasma gondii tissue cysts in enhanced pork loin. Journal of Food Protection. 69: 1961-1965.
Interpretive Summary: The protozoan parasite Toxoplasma gondii is one of the most common parasitic infections of man and other warm-blooded animals. It has been found worldwide from Alaska to Australia. Nearly one-third of the human population has been exposed to this parasite. In most adults, infection does not cause serious illness, but it can cause blindness and mental retardation in congenitally infected children and devastating disease in immunocompromised individuals. Consumption of raw or undercooked meat products containing T. gondii tissue cysts is considered to be a major risk factor associated with T. gondii infection. Bioassays, serological, and molecular studies have demonstrated natural infection in pigs destined for human consumption. Retail meat cuts of pork are frequently enhanced with salt solutions to improve flavor, extend shelf life, reduce microbial contamination, and improve tenderness. In this study, we have investigated the effect of storage time and temperature on the viability of T. gondii tissue cysts in pork loins enhanced with commonly used salt solutions. Results demonstrated that the enhancement solutions tested were effective at eliminating viability of Toxoplasma tissue cysts in pork loins within 8 hours of injection, and that meat case temperatures that were at or below 0oC (32oF) eliminated viability of Toxoplasma tissue cysts in pork loins within 7 days of storage at those temperatures.
A study of the effect of exposure time and storage temperature on tissue cyst viability in pork loins pumped with commonly used meat enhancement solutions was performed using tissues from experimentally infected pigs. Pork loins were stored for 8, 16, 24, 32, or 40 hours at 4oC before feeding to T. gondii-seronegative cats to determine how quickly the loss of tissue cyst viability occurred in enhanced loins. In a second experiment, pork loins were collected from pigs experimentally infected with T. gondii and stored at temperatures found in a survey of retail meat case temperatures before feeding to T. gondii-seronegative cats to determine the effect of typical meat case storage temperatures on tissue cyst viability in pork loins. In both experiments, cat feces were examined for 14 days after feeding of meat to assess oocyst shedding. The present study demonstrated that solutions containing 2% sodium chloride or 1.4% potassium or sodium lactate are effective at eliminating viability of Toxoplasma tissue cysts in pork loins within 8 hours of injection, and that meat case temperatures that were at or below 0oC (32oF) eliminated viability of Toxoplasma tissue cysts in pork loins within 7 days of storage at those temperatures.