Assessment of recommended thermal inactivation parameters for fruit juices

The aim of this study was to evaluate the efficacy of recommended and recalculated thermal process parameters to achieve mandatory 5-log reduction of shiga toxin-producing Escherichia coli (STEC), Salmonella, and Listeria monocytogenes in fruit juices in the United States. Logarithms of published D-values of pathogens were plotted against temperatures (°C) to recalculate the pasteurization parameters for apple, orange and all studied fruit juices. Fruit juices were inoculated with non-adapted cells grown in TSB without glucose and acid adapted strains grown in TSB containing 1% glucose and TSB with adjusted pH to 5.0 with 1 N HCl. Microcapillary tubes with inoculated apple and orange juice were heat treated in water bath at 71 ± 1 °C for 6, 12, 36, and 48 ± 1 s. Acid adaptation increased the heat resistance of STEC, Salmonella, and L. monocytogenes. Different acid adaptation procedures affected thermal tolerance responses of tested strains. A 5-log reduction of Salmonella and STEC at 71.1 °C was achieved with minimum heat treatment for 6 s in apple juice and 6 to 12 ± 1 s in orange juice. Data presented in this study suggests that current recommended pasteurization parameters failed to reduce viable acid adapted L. monocytogenes by 5-log. •Pasteurization parameters were recalculated for fruit juices based on published data.•Recommended and recalculated parameters were tested for apple and orange juice.•Acid adaptation methodology affected thermal tolerance responses of pathogens.•Recommended processing times failed to achieve 5-log reduction of L. monocytogenes.•36 s at 71.1 °C achieved a 5-log reduction of pathogens in both fruit juices.