Agriculture Reference
In-Depth Information
from fresh produce purchased in host nations with lax standards for hygiene, sanita-
tion, and pesticide use that could contaminate produce. The PCS can also be confi g-
ured to generate less stringent conditions of chlorine dioxide for treating fresh produce
to achieve food safety without compromising food quality (Feeherry and others 2007).
The ability of the PCS to kill harmful foodborne pathogens (
E. coli
and
L. mono-
cytogenes
) on fresh produce was tested using a spot-inoculation method of high levels
of pathogens on the exterior surfaces of tomatoes. Specifi cally, the exterior surfaces
of 25 g samples of tomato wedges were inoculated with either 10
5
CFU/g
L. monocy-
togenes
OSY-8578 (obtained from The Ohio State University) or with 10
6
CFU/g
E. coli
ATCC 11229 and air-dried in a sterile bio-hood for 15 min. After the inoculum
dried, the tomato wedges were placed inside the PCS and tested under various condi-
tions of chlorine dioxide concentration and exposure time (Fig. 14.5). In some
instances,
B. stearothermophilus
and
B. atrophaeus
spore bioindicators were also
placed inside the PCS during the treatment.
In all cases, treatment conditions were found that inactivated the target microorgan-
isms to render tomatoes safe from these foodborne pathogens without compromising
the red color of the exterior tomato surfaces (Table 14.2). The color of whole tomatoes
was only slightly diminished by the chlorine dioxide treatment. Similar treatments
with uninoculated apple slices also tended not to discolor the skin color. The pulp
Figure 14.5.
A typical PCS setup to inactivate
E. coli
or
L. monocytogenes
on exterior
tomato surfaces is shown.
