Purpose: In this study apple cider and skim milk (2% fat) were inoculated with Shiga toxin-positive E. coli O157:H7 and subsequently exposed to a cocktail of bacteriophages (CB), ambient PEF, heat-enhanced PEF (H/PEF) and combinations of these treatments.
Methods: Bacteriophages V10, V13, V15, and RV5 were combined in a cocktail for STEC inactivation in both liquid foods at 1:10 dilution, while both beverages were PEF-processed with electric field strengths of 38 kV/cm, for 1683 µs and at ≤45 °C, and H/PEF-treated with the same PEF processing conditions but a higher temperature level of ≤65 °C. Treated samples were stored at 4 °C for up to 42 days.
Results: In skim milk maximum STEC inactivation of 1.2, 1.7, 3.6, 1.5, and 3.7 log were achieved by CB, PEF, H/PEF, PEF/CB, and H/PEF/CB, respectively, while the same treatments led to corresponding STEC reductions of up to 2.2, 3.4, 4.6, 3.3, and 4.6 log in apple cider over the duration of the study. Both H/PEF and H/PEF/CB showed better efficacy for the reduction of the STEC (P < 0.05) than the other treatments.
Significance: The findings of this study show that H/PEF and H/PEF/P were the most effective treatments for STEC inactivation in both beverages, thus, representing promising liquid decontamination strategies. Disinfection with the non-thermal processing techniques had an overall greater impact on apple cider than in skim milk, thereby, suggesting that liquid foods with relatively high protein and fat contents may act as a greater barrier to the treatments’ effectiveness than those with a comparatively high sugar composition.