(337y) Kinetic Parameters of Bacillus Atrophaeus in Response to Vapor and Liquid Hydrogen Peroxide at Aseptic Filler Tunnel Temperatures

Hydrogen peroxide (H₂O₂) is widely recognized for its effectiveness as a sterilizing agent. Its efficacy in aseptic package sterilization, especially in the liquid phase, has been well-established. However, there remains a need for extensive research on microbial inactivation parameters and the influence of temperature on vapor H₂O₂. This study addresses these gaps by estimating model parameters for liquid and vapor hydrogen peroxide treatments on B. atrophaeus spores, a surrogate organism used for aseptic filler validation. For liquid hydrogen peroxide (LHP), temperatures ranging from 70 to 25 °C were used, while vapor hydrogen peroxide (VHP) challenge studies were performed at temperatures corresponding to aseptic tunnel temperatures (60 to 43.3 C). The exposure times ranged from 1-18 seconds, and VHP concentrations of 4450, 3337, and 2503 parts per million (PPM) were utilized. The relative humidity was maintained at 0.2-0.5% in the tunnel and VHP carrying lines throughout the process. Log-linear and Weibull models were employed as inactivation models for LHP and VHP to estimate the kinetic parameters at a reference temperature of 60 °C with a peroxide concentration of 33%. For LHP, the log-linear model yielded D values of 0.391 minutes and a z value of 63 °C, while the Weibull model estimated δ values of 0.19 minutes and a z value of 58.3 °C for 33% peroxide. The performance of the models was evaluated using metrics such as root mean square error (RMSE), a sum of squares, and the Akaike information criterion (AIC). The RMSE values varied from 0.76 to 0.81 log CFU/ml, the sum of squares ranged from 90.2 to 77.96, and AIC scores ranged from -47.93 to -66.70 for the log-linear and Weibull models. For VHP treatments at a concentration of 2503 PPM, the log-linear model estimated D values of 0.038 minutes and a z value of 65 °C, while the Weibull model yielded δ values of 0.021 minutes and a z value of 67 °C. VHP treatments ranged from 0.49 to 0.43 log CFU/ml for RMSE, 19.06 to 15.09 for the sum of squares, and -114.22 to -132.06 for AIC scores in the log-linear and Weibull models. In conclusion, this study provides valuable insights into the effectiveness of LHP and VHP treatments on B. atrophaeus spores under different temperature conditions. The estimated model parameters can be used to design effective commercial package sterilization processes and aseptic filler validation.