Submitted to: Journal of Food Protection
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/21/2005
Publication Date: 8/1/2005
Citation: Chen, H., Hoover, D., Kingsley, D.H. 2005. Temperature and treatment time influences pressure inactivation of feline calicivirus, a norovirus surrogate. Journal of Food Protection. 68: 2389-2394. Interpretive Summary: Previous work has demonstrated the utility of high pressure processing to inactivate foodborne viruses. In this publication, we determined the relationships between virus inactivation at different treatment times and temperatures using feline calicivirus, a virus genetically related to foodborne norovirus. In particular, we find that cooler temperatures in the range of -10C to +10C result in enhanced virus inactivation as compared with room temperature. Warmer temperatures, above +30C, also result in greater inactivation than at room temperature. The incremental study of treatment time’s effect on virus inactivation reveals that as treatment times increase, a diminishing amount of inactivation is observed, termed tailing. This “tailing effect” is similar to the log-logistic and Weibull inactivation models described for bacterial inactivation. This study begins to lay the groundwork for defining how processing conditions may potentially influence inactivation of norovirus within foods.
Technical Abstract: Pressure inactivation curves of feline calicivirus (FCV), KCD strain in Dulbecco’s modified Eagle media with 10% fetal bovine serum were obtained at 200 and 250 MPa as a function of time at room temperature. Pressure inactivation curves at 200 and 250 MPa were also determined as a function of temperature ranging from -10 to 50ºC at treatment times of 4 min and 2 min respectively. Tailing was observed for inactivation as a function of treatment time, indicating that the linear model was not adequate for describing these curves. The two nonlinear models, the log-logistic and Weibull models consistently produced better fits to the inactivation curves than the linear model. The log-logistic model had a mean square error (MSE) of 0.381, the Weibull model a mean MSE value of 0.425, and the linear model a MSE of 0.748. For inactivation as a function of temperature, FCV was most resistant to pressure at 20C. Temperatures above and below 20ºC significantly increased pressure inactivation of FCV. A 4-min treatment of 200 MPa at -10 and 50C reduced the titer of FCV by 5.0 and 4.0 log10, respectively; whereas at 20C the same treatment only reduced the titer by 0.3 log10. These novel results point to the potential of using alternate temperatures above, and particularly below, room temperature to lower the pressure needed to cause the desired level of virus inactivation.