Multi-state
outbreaks of salmonellosis due to the consumption of contaminated
fresh tomatoes (Lycopersicon esculentum) have recently occurred in
the United States. This study investigated the survival of a five-serovar
(serotype) Salmonella cocktail artificially inoculated onto tomato
and packing line surfaces when held at various temperature and relative
humidity (RH) combinations over 28 days. Packinghouse surfaces included
stainless steel, polyvinyl chloride (PVC), sponge rollers, conveyor
belts, and unfinished oak wood surfaces. Packinghouse climates were
generated to simulate conditions in Florida during late Spring (30
°C days/ 80% RH) and fall/ winter (20 °C/ 60% RH) months.
Additionally, survival of Salmonella on tomatoes in standard ripening
room conditions (20 °C/90% RH) was evaluated. Recovery of inocula
was by a vigorous shake/ hand rub method. After 28 days, Salmonella
populations remained detectable on tomato surfaces regardless of environmental
conditions. Inoculated Salmonella populations tested at spring conditions
declined to undetectable levels on all packing line materials by day
11, with the exception of the unfinished oak wood, which reached undetectable
levels by day 21. In contrast, inoculated Salmonella populations tested
at fall/ winter conditions declined to undetectable levels on sponge
rollers and conveyor belts by day 7 and day 21, respectively. Stainless
steel, PVC, and wood surfaces supported the survival of detectable
populations of Salmonella over the 28-day sampling period. Results
of this study demonstrate the potential for Salmonella to persist
on tomato and packing line surfaces under common environmental conditions.
Results from this Florida study emphasize the need for good sanitary
practices in packing sheds. Information that will be helpful in developing
good management practices to reduce the risk of produce contamination
in packing sheds can be obtained by contacting:
Frank J. Dainello, PhD., Extension Horticulturalist, Dept. of Hort
Science, Rm 225, MS 2134, HFSB, TAMU, College Station, Texas 77843
