The three slices were placed into sterile bags and stomached for 60 s in 10 mL
peptone water. The number of viable L. monocytogenes for each
samplewas determined by plating triplicate aliquots (0.1 mL) of the stomached apple/peptonewater mixture onto separate Oxford agar
plates, supplemented with Oxford Listeria Selective Supplement.
The plates were incubated at 35 ± 2 C for 48 ± 4 h and the CFU/g
was counted as above.