Food Protection Trends - March/April 2025 - 126

Figure 1.
S. Typhimurium
ATCC 14028
S. Typhimurium
ATCC 13311
S. Typhimurium
ATCC 6962
Each strain attached for 20 min
Bacterial numbers
determined on
TAL medium
Peel baby cucumber
Stainless-steel peeler
Plastic peeler
Peel baby cucumber
Rinse peeled cucumber and
peeler respectively with
~20 ml of water
Bacterial numbers determined on TAL medium
Log percentage of transfer onto the flesh and
peelers determined
Stainless-steel peeler
Plastic peeler
Rinse peeled cucumber and
peeler respectively with
~20 ml of water
Bacterial numbers determined on TAL medium
Log percentage of transfer onto the flesh and
peelers determined
Figure 1. Experimental design for evaluating transfer of Salmonella from skin to flesh and peelers during peeling of baby cucumbers.
log transformed percentage transfer of Salmonella cells from
unrinsed cucumber skin to flesh by using either a plastic or
stainless steel peeler are shown in Figure 2A. A lower number
of Salmonella cells across all strains were transferred to a
rinsed peeled cucumber after peeling than to the unrinsed
peeled cucumber. The transfer of cells of both Salmonella
Typhimurium strains on the peeled cucumber was higher
after using the plastic peeler than after using the stainless
steel peeler. Plastic is more hydrophobic than stainless steel,
and Salmonella is more adhesive on hydrophobic surfaces
(30). Overall, the transfer rate of Salmonella Typhimurium
was higher than that of Salmonella Newport when peeling
an unrinsed cucumber with a plastic peeler as compared
with a stainless steel peeler. The transfer rate of Salmonella
Typhimurium ATCC 14028 was significantly higher (P ≤
0.05) than that of the other strains in this study. The type of
peeler surface, serovar, and strains may affect the transfer rate
of Salmonella on cucumbers. In previous studies, more of the
Salmonella Newport cells were left on the peeled cucumber
skin during peeling than were transferred to the cucumber
flesh or the peelers (16).
The log transformed percentage transfer of Salmonella
cells from unrinsed cucumber skin to plastic or stainless steel
peelers is shown in Figure 2B. Use of a plastic peeler generally
resulted in a significantly higher transfer (P ≤ 0.05) than use
of a stainless steel peeler for both Salmonella Typhimurium
strains on an unrinsed cucumber. However, transfer of cells
was lower for Salmonella Typhimurium ATCC 13311 on
rinsed peelers after peeling. Salmonella Newport exhibited
a different trend, with use of a stainless steel peeler having
a slightly higher transfer rate than use of a plastic peeler,
whereas the reverse was observed with the rinsed peelers
after peeling. Some researchers have reported that Salmonella
attaches better to hydrophobic surfaces such as plastic than
to hydrophilic surfaces such as stainless steel (4, 15, 32).
However, in previous studies the greater attachment of
Salmonella on hydrophilic surfaces such as stainless steel
than on hydrophobic surfaces was associated with higher free
surface energy (8, 22). Bacterial surface hydrophobicity may
also be associated with the attachment of Salmonella onto a
surface (31). The log percentage transfer of Salmonella from
the unpeeled cucumber to both plastic and stainless steel
peelers across all strains was negative, indicating that most of
the Salmonella cells were either removed during the rinsing
process or were transferred to the peeled cucumber.
Salmonella transfer from rinsed cucumber skin to flesh
and peelers
Attachment of all Salmonella strains was ~6.75 to 7.40
log CFU/g on baby cucumbers after they were rinsed with
water. Rinsing with water significantly reduced Salmonella
attachment on unpeeled cucumbers. Similar to the unrinsed
cucumbers, no significant differences (P > 0.05) between
Salmonella strains were found for attachment on cucumbers
after they were rinsed with water. The log transformed
percentage transfer of Salmonella from rinsed cucumber
March/April Food Protection Trends 126
Rinse baby cucumber with ~20 ml
of water

Food Protection Trends - March/April 2025

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