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Home Washing
Methods in Controlling Microbial Contamination on Fresh Produce
Agnes
Kilonzo-Nthenge, Fur-Chi Chen, and Sandria L. Godwin
Institute of
Agricultural and Environmental Research
Seminar Series
Tennessee State University, Nashville, TN
March 9, 2005
Much
effort has been focused on sanitation of fresh produce at a commercial
level; however, few options are available to the consumer. The purpose
of this study was to determine the potential of different washing
methods in reducing or removing bacterial contamination on fresh produce
in a home setting. Lettuce, broccoli, apples, and tomatoes were
inoculated by dipping them in a suspension containing approximately 8.0
log CFU/ml of Listeria innocua and then followed by a 2 min
soaking in tap water, commercial vegetable wash, lemon juice (13%), or
vinegar (5%). After the soaking step, each produce was subjected to some
or all of the following cold tap water treatments: rub and rinse, rinse
only, brush and rinse, wet and dry paper towel wipe. A rinse or soak
method reduced L. innocua population in lettuce and broccoli
within the range 1.41 to 1.88 log CFU/g and in apples and tomatoes
within 2.00 to 2.89 log CFU/g. Wiping apples with a wet and dry paper
towel showed low bacterial reductions of 0.96 and 0.64 log CFU/g,
respectively. Wiping tomatoes with wet or dry paper towel did not reduce
L. innocua significantly (P > 0.05). Generally, cold running tap
water, vinegar, lemon, and vegetable wash solutions reduced L.
innocua population within the same log units. It is cost effective
for consumers to use cold running tap water instead of other washing
solutions to reduce or remove microbial contamination on fresh produce.
Educators and extension workers may, therefore, consider it appropriate
to remind consumers through workshops or focus groups, to rub or brush
fresh fruits and vegetables in cold running tap water.
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