Thermal Inactivation Kinetics of Human Norovirus Surrogates and Hepatitis A Virus in Turkey Deli Meat

Abstract

Human noroviruses (HNoV) and hepatitis A virus (HAV) have been implicated in outbreaks linked to the consumption of presliced ready-to-eat deli meats. The objectives of this research were to determine the thermal inactivation kinetics of HNoV surrogates (murine norovirus 1 [MNV-1] and feline calicivirus strain F9 [FCV-F9]) and HAV in turkey deli meat, compare first-order and Weibull models to describe the data, and calculate Arrhenius activation energy values for each model. The D (decimal reduction time) values in the temperature range of 50 to 72°C calculated from the first-order model were 0.1 ± 0.0 to 9.9 ± 3.9 min for FCV-F9, 0.2 ± 0.0 to 21.0 ± 0.8 min for MNV-1, and 1.0 ± 0.1 to 42.0 ± 5.6 min for HAV. Using the Weibull model, the tD = 1 (time to destroy 1 log) values for FCV-F9, MNV-1, and HAV at the same temperatures ranged from 0.1 ± 0.0 to 11.9 ± 5.1 min, from 0.3 ± 0.1 to 17.8 ± 1.8 min, and from 0.6 ± 0.3 to 25.9 ± 3.7 min, respectively. The z (thermal resistance) values for FCV-F9, MNV-1, and HAV were 11.3 ± 2.1°C, 11.0 ± 1.6°C, and 13.4 ± 2.6°C, respectively, using the Weibull model. The z values using the first-order model were 11.9 ± 1.0°C, 10.9 ± 1.3°C, and 12.8 ± 1.7°C for FCV-F9, MNV-1, and HAV, respectively. For the Weibull model, estimated activation energies for FCV-F9, MNV-1, and HAV were 214 ± 28, 242 ± 36, and 154 ± 19 kJ/mole, respectively, while the calculated activation energies for the first-order model were 181 ± 16, 196 ± 5, and 167 ± 9 kJ/mole, respectively. Precise information on the thermal inactivation of HNoV surrogates and HAV in turkey deli meat was generated. This provided calculations of parameters for more-reliable thermal processes to inactivate viruses in contaminated presliced ready-to-eat deli meats and thus to reduce the risk of foodborne illness outbreaks.

FIG 1

Survival curves of human norovirus surrogates and hepatitis A virus in turkey deli meat at 50°C. (A) FCV-F9; (B) MNV-1; (C) HAV. Solid lines with filled circles, experimental; dashed lines with open circles, first-order model; dashed lines with open diamonds, Weibull model.

FIG 2

The fit of the power-law model to Weibull model parameter b as a function of temperature for the constant n. (A) FCV-F9 at n = 0.89 (R² = 0.99); (B) MNV-1 at n = 1.31 (R² = 0.99); (C) HAV at n = 1.23 (R² = 0.96).

FIG 3

The fit of the log-logistic model to inactivation rate constants for each model as a function of temperature. (A) FCV-F9, first-order model (R² = 0.97); (B) FCV-F9, Weibull model (R² = 0.98); (C) MNV-1, first-order model (R² = 0.98); (D) MNV-1, Weibull model (R² = 0.99); (E) HAV, first-order model (R² = 0.96); (F) HAV-Weibull model (R² = 0.97).