Cleaning of knives and boards after individual operations would
be an advantageous practice to minimize cross-contamination of
diverse food items; however, Jevsnik et al. (2008) reported that 66%
of consumers (n ¼ 1030) did not wash knives before reuse. Unfortunately,
it would appear that improvements in that practice have
not occurred since that study was conducted as Kennedy et al.
(2011) reported that 50% of their consumers (n ¼ 60) only rinsed
the contaminated knife with water and another 20% did not wash
the contaminated knife at all. Regardless of these disappointing
statistics, there is also the realization that cleaning knives is not a
guarantee that all contamination will be removed. When six E. coli
O157:H7 and Salmonella-contaminated knife blades (3.6e3.7 log/
cm2
) were wiped with a dry sterile cotton towel, both pathogens
were present after this operation (2.4e3.0 log/cm2
) and contamination
of cucumbers sliced with these wiped knives also occurred
(1.9e2.6 log CFU/cm2
) (Perez et al., 2012). Furthermore, wiping
knives with a sponge hydrated with soap (1% lauryl sulfate-based
detergent) and rinsing the knives with warm running water for
10 s before slicing cucumbers still led to contamination of 50% of
those cucumbers (0.1e0.2 log/cm2
). Given these results and consumers'
propensity to leave knives dirty, transfer of pathogens on
knives should be conducted in the presence of surface residues. In
studies where residue was considered as a variable, cell attachment
differed depending on the nature of the residue (Whitehead et al.,
2010).