Development of a high pressure processing inactivation model for hepatitis A virus.

High pressure processing (HPP) inactivation data were obtained for hepatitis A virus (HAV) suspended in buffered growth medium containing salt at either 15 or 30 g/liter. Pressures between 300 and 500 MPa were applied for treatment times of 60 to 600 s. In medium containing 15 g/liter salt, the HAV titer was reduced by approximately 1 and 2 log 50% tissue culture infectious dose units (TCID50) per ml after 600 s of treatment with 300 and 400 MPa, respectively. Under the same treatment conditions but in medium containing 30 g/liter salt, HAV was reduced by <0.50 log TCID50/ml. HAV was inactivated by >3 log TCID50/ml after treatment with 500 MPa for 300 and 360 s in medium containing 15 and 30 g/liter salt, respectively. Weibull and log-linear models were fitted to inactivation data. Individual Weibull curves generally provided a good fit at each pressure and salinity, but the curve shapes were qualitatively inconsistent between treatments, making interpolation between pressures difficult and unreliable. High variability was observed in the inactivation data, but the log-linear model described the entire data set and interpolated between specific treatment conditions. Therefore, this model was evaluated by using high pressure to treat HAV artificially inoculated into Pacific oyster (Crassostrea gigas) homogenate adjusted to 15 or 30 g/liter salinity. The log-linear model generally provided fail-safe predictions at pressures > or = 375 MPa and may aid shellfish processors wishing to incorporate HPP into an oyster processing regime. Additional inactivation data with greater reproducibility should be collected to enable expansion of the model and to increase the accuracy of its predictions.