Validation of apple cider pasteurization treatments against Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes

Time and temperature pasteurization conditions common in the Wisconsin cider industry were validated using a six-strain cocktail of Escherichia coli O157:H7 and acid-adapted E. coli O157:H7 in pH- and degrees Brix-adjusted apple cider. Strains employed were linked to outbreaks (ATCC 43894 and 43895, C7927, and USDA-FSIS-380-94) or strains engineered to contain the gene for green fluorescent protein (pGFP ATCC 43894 and pGFP ATCC 43889) for differential enumeration. Survival of Salmonella spp. (CDC 0778, CDC F2833, and CDC HO662) and Listeria monocytogenes (HO222, F8027, and F8369) was also evaluated. Inoculated cider of pH 3.3 or 4.1 and 11 or 14 degrees Brix was heated under conditions ranging from 60 degreesC for 14 s to 71.1 degreesC for 14 s. A 5-log reduction of nonadapted and acid-adapted E. coli O157:H7 was obtained at 68.1 degreesC for 14 s. Lower temperatures, or less time at 68. VC, did not ensure a 5-log reduction in E. coli O157:H7. A 5-log reduction was obtained at 65.6 degreesC for 14 s for Salmonella spp. L. monocytogenes survived 68.1 degreesC for 14 s, but survivors died in cider within 24 h at 4 degreesC. Laboratory results were validated with a surrogate E. coli using a bench-top plate heat-exchange pasteurizer. Results were further validated using fresh unpasteurized commercial ciders. Consumer acceptance of cider pasteurized at 68.1 degreesC for 14 s (Wisconsin recommendations) and at 71.1 degreesC for 6 s (New York recommendations) was not significantly different. Hence, we conclude that 68.1 degreesC for 14 s is a validated treatment for ensuring adequate destruction of E. coli O157:H7, Salmonella spp., and L. monocytogenes in apple cider.