In Table 5 is presented the population of E. coli O157 EDL-932
and L. monocytogenes Scott A which survived on black Kalamata olives
and green olives Chalkidikis fermented by OSC after immersion
in peptone/saline suspension containing 5 × 106 CFU/ml of
E. coli or L. monocytogenes for 30 min followed by rinsing in distilled
H2O. After the above treatment, the population of viable
foodborne pathogens detected in the pulp of the artificially contaminated
olives did not exceed 1.97 and 1.64 log CFU/g of E. coli
O157 and L. monocytogenes, respectively (Table 5).
Rinsing of olives
after submersion in foodborne pathogen solution contributes to remove
“loosely attached” microorganisms to olive skin. Thus “strongly attached”
contaminated foodborne pathogens were detected directly
after rinsing (Table 5)Higher populations of both foodborne pathogens
were detected in natural black olives cv. Conservolea fermented by the
indigenous microbiota (pH 3.95 and 6.02% NaCl in the final product)
after submersion in the foodborne pathogen solution and left to dry
During subsequent storage at 22 or 4 °C for 7 days using as a carrier
peptone/saline or distilled water the population of L. monocytogenes
Scott A was further reduced under the detection limit in both olive cultivarswhereas
the population of E. coli O157 EDL-932 could be detected
only in olives stored in peptone/saline at 22 °C for 7 days indicating a
protective effect of the above suspension medium(Table 5). Alkali treated
green table olives cv. Chalkidiki fermented by L. pentosus (pH 4.2 and
6% NaCl in the final product) when stored at 20 °C in a new brine containing
6% NaCl and 7 log CFU/ml E. coli O157:H7 or L. monocytogenes
showed a reduction of the inoculated foodborne population under the
detection limit of the enumerationmethod after 5 or 9 days, respectively