VegNet Vol. 13,
No. 21.
On the WEB at: http://vegnet.osu.edu
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fax, Call 614-292-3857
In This Issue
1. E. coli O157:H7 Outbreak in Spinach
2. Crop Report from Brad Bergefurd
SPECIAL EDITION of the VegNet
Newsletter
[Editor’s
Note: This special edition presents a summary of some of the latest information
on the E. coli outbreak in spinach. The article begins with excerpts from a
review paper soon to be published in the Journal of Food Science written by
scientists from OSU. The paper was submitted in April 2006 and details
vegetable food safety concerns that are so much in the news today and affect
our industry. Thanks to Dr. K. Lee (OSU Food Sci.
Dept.) for giving me an advanced copy as well as permission to use some of this
information in our newsletter. The end of the newsletter contains the latest
news release from the FDA as well as some information on the Lettuce Safety
Initiative and the 2004 Action Plan to Minimize Foodborne
Illness Associated with Fresh Produce Consumption. More complete and detailed
information can be found by following the web links to the FDA]
Fruit and Vegetable
Microbiological Safety Concerns
From the paper: “Interactions Affecting the
Proliferation and Control of Human Pathogens on Edible Plants” by D.
ARUSCAVAGE, K. LEE, S. MILLER, AND J.T. LEJEUNE to be published in the Journal
of Food Science MS20060206 Submitted 4/12/2006, Accepted 8/15/2006. Authors Aruscavage and Lee are withDept. of Food Science andTechnology, TheOhio StateUniv.,
ABSTRACT: Pathogens on edible plants present a
significant potential source of human illness. From 1991 to 2002, 21% ofEscherichia coli O157: H7 outbreaks were from
produce-related sources. E. coli O157and other enteric bacteria can
contaminate the surface of edible plants both pre- and postharvest.
Some pathogens do not survive on the leaf surface or are removed by washing,
but a significant portion of these enteric pathogens can persist on the surface
and proliferate. Proliferation of these dangerous pathogens can increase the
likelihood of foodborne disease associated with fresh
or minimally processed produce.
Increased consumption of minimally processed fruit and vegetables has
focused attention on how the microenvironment of these plants affects produce
safety. This microenvironment can help or hinder food safety, affecting
proliferation and persistence of enteric pathogens on plants.
Unreported before the 1990s, it is no longer surprising that a
significant number of outbreaks of foodborne disease
can be linked to fresh produce. By the mid 1990s, illnesses associated with
cantaloupe, tomatoes, alfalfa, lettuce, and several other fruits and vegetables
were documented (Tauxe 1997). The United States
Department of Agriculture (USDA) recommends adults consume five cups of fruit
and vegetable products daily to maintain good health (mypyramid.gov). The
The most common bacterial enteropathogens
associated with fruits and vegetables are Salmonella spp.
(Thunberg and others 2002). In 1990, a multistate
outbreak of salmonellosis in the Midwestern United
States was caused by consumption of raw tomatoes (Hedberg
and others 1999). Cantaloupe and strawberries were also identified as sources
of Salmonella outbreaks in the 1990s (Hedberg and
others 1999). Rangel and others (2005) showed produce was the transmission vehicle
for E. coli O157:H7 in 21% of the food borne outbreaks from 1982 to 2002 with
the first recorded incident occurring on 1991. From 2000 to 2004, produce related
outbreaks were usually the second most common identified outbreaks of E. coli
O157 (Figure 1). E. coli O157 outbreaks were associated with apple cider,
lettuce, radish, alfalfa sprouts, and other mixed salads since 1991 (Beuchat 2002).
Figure 1
Washing of Edible Plants
Processing of fruits and vegetables results
in cut surfaces and a prepackaged nonsterile food
(Nguyen-the and Carlin 1994). Packaging implies a level of
safety to some consumers that may or may not be achieved. Processing includes
washing, trimming, possibly peeling or slicing, and a sanitation step
(Carmichael and others 1999).Washing and sanitation steps are critical with
produce because this type of food is often eaten raw.
Johnston and others (2005) observed an increase in microbial proliferation
from harvest to processing. They found a 10-fold increase in microbial counts
for cilantro from harvest samples to boxed and processed samples.
A produce sanitation step typically involves a solution of 50 ppm to 200 ppm chlorine that may
or may not be necessary. Chlorine is as successful at removing bacteria as non chlorinated
water, but it is necessary to keep the wash water free of contaminants (Zagory 1999). Chlorinated water does not sterilize produce,
but Zhuang and others (1995) suggested using 200 ppm free chlorine in wash water to ensure some reduction of
Salmonella Montevideo from tomatoes. Some producers feel that high concentrations
of chlorine in the wash water cause esthetic problems with the product (Hurst and
Schuler 1992). Beuchat (1999) found deionized water compared with a 200 ppm
chlorine solution was equally successful at removing pathogens from the surface
of lettuce. Solomon and others (2002a) used a 200 ppm
chlorine solution to clean lettuce and found that it did not remove E. coli
O157. Among potential reasons for the failure of chlorine washes are protected
sites on the plant where these bacteria hide, avoiding contact with the wash (Leben 1988). Raiden and others
(2003) determined detergents were as successful as water at removing Salmonella
from strawberries and tomatoes. Most research indicates that enteric pathogens
are removed from produce surfaces effectively with water, with chlorine, and
with common detergents, yet chlorine is often considered mandatory for produce sanitation.
Chlorine may help keep the rinse water clean but keep in mind there are other
ways to do this.
Chlorinated water may only be as effective as water at
disinfecting produce, but Han and others (2000) found chlorine dioxide (ClO2) was
much more effective than water. The authors found a 3.0 log10 reduction of E.
coli O157:H7 when disinfected with 0.62 g/L ClO2 and a 6.5 log10 reduction of
E. coli O157:H7 when 1.24 g/L ClO2.New technologies show promise for produce sanitation
to ensure product safety. Harris and others (1999) tested an alkaline produce wash
with Q15 generally regarded as safe (GRAS) components. The produce wash reduced
Salmonella 2 to 4 logs more than the sterile water on the surface of tomatoes.
With current technology and packaging of fresh produce,
microorganisms are present at the time of purchase in grocery stores. Farmers
and processors must be vigilant in food safety, but so must consumers. Proper
storage and cleaning before eating will help prevent foodborne
disease associated with fresh produce. The U.S.FDA recommends buying produce
that is not bruised or damaged and buying cut produce that is refrigerated or
packed in ice. It is also recommended that all produce be washed with water
before consumption, even if it is prepackaged. The U.S. FDA suggests scrubbing produce
capable of handling it, but does not recommend use of detergents. It is
important to realize that produce safety is now a partnership that requires
attention from farmers, processors, retailers, and consumers.
Conclusion
In 2004, the FDA instituted an action plan to reduce food borne disease
(see below) associated with fresh produce. The action plan calls for
improvement in every step of produce production from the farm to the retail
store (cfsan.fda.gov/∼dms/prodpla2.html).
To help in the improvement in these areas, we must fully understand conditions
that affect the proliferation of enteric pathogens(Table
1). Microenvironmental changes can enhance or
adversely affect survival and proliferation of these transient organisms.
Surface characteristics can determine if enteric pathogens adhere to food, for
example, protected sites on a leaf surface are important for survival of an
organism. Such natural sites and created sites such as wounds may enhance survival
and proliferation because additional nutrients and protection from drastic
environmental shifts will help any microorganism not normally present in the phyllosphere.
FDA Statement on Foodborne
E. coli O157:H7 Outbreak in Spinach
http://www.fda.gov/bbs/topics/NEWS/2006/NEW01466.html
FOR IMMEDIATE RELEASE P06-146
Update
To
date, 183 cases of illness due to E. coli O157:H7 infection have been reported
to the Centers for Disease Control and Prevention (CDC), including 29 cases of
Hemolytic Uremic Syndrome (HUS), 95 hospitalizations
and one death.
FDA
is working closely with CDC and the state of
Consumers
are advised not to purchase or consume fresh spinach if they cannot verify that
it was grown in areas other than the three
Other
produce grown in these counties is not implicated in this outbreak. Processed
spinach (e.g., frozen and canned spinach) is also not implicated in this
outbreak.
Industry
is working to get spinach from areas not implicated in the current E. coli
O157:H7 outbreak back on the market.
Investigators
from FDA, CDC and the state of
States Affected;
Canadian case identified
The
26 affected states are: Arizona (7), California (1), Colorado (1), Connecticut
(3) Idaho (4), Illinois (1), Indiana (9), Kentucky (8), Maine (3), Maryland
(3), Michigan (4), Minnesota (2), Nebraska (9), Nevada (1), New Mexico (5), New
York (11), Ohio (24), Oregon (6), Pennsylvania (8), Tennessee (1), Utah (18), Virginia
(2), Washington (3), West Virginia (1), Wisconsin (47), and Wyoming (1).
In
addition,
Laboratory Findings
The
Pennsylvania Department of Health has confirmed that the strain of E. coli
O157:H7 connected with the outbreak has been isolated from a bag of Dole baby
spinach in that state.
The Utah
Department of Health (UDOH) and the Salt Lake Valley Health Department (SLVHD)
have confirmed that E. coli O157:H7, the same strain as that associated with
the outbreak, has been found in a bag of Dole baby spinach purchased in Utah
with a use by date of August 30, 2006. Laboratory tests were conducted by the
Utah Public Health Laboratory (UPHL).
The New Mexico
Department of Health announced on
Five (5) Recalls http://www.fda.gov/bbs/topics/NEWS/2006/NEW01466.html
Go
to the actual news release (URL listed above) for a complete list of recalled
products by company and product type.
Lettuce Safety Initiative
The
FDA developed the Lettuce Safety Initiative
www.cfsan.fda.gov/~dms/lettsafe.html
in response to recurring outbreaks of E. coli O157:H7 in lettuce. As a
result of this outbreak, the initiative has been expanded to cover spinach.
The objectives
of the Lettuce Safety Initiative are as follows:
Assess current
industry approaches and actions to address the issue of improving lettuce
safety. If appropriate, stimulate segments of the industry to further advance
efforts in addressing all aspects of improving lettuce safety.
Alert consumers
early and respond rapidly in the event of an outbreak.
Document
observations that identify practices that potentially lead to product
contamination. Then,
develop and/or refine guidance and policy that will minimize opportunities for
future outbreaks and/or identify research needs.
Consider
regulatory action, as appropriate, based on conditions and practices that could
lead to, or spread contamination, or when lettuce has been adulterated.
This
initiative is based on the 2004 Produce Safety Action Plan, intended to
minimize the incidence of food borne illness associated with the consumption of
fresh produce.
FDA
continues to work closely with the CDC and state and local agencies to
determine the cause and scope of the E. coli 0157:H7 outbreak in spinach.
Please check www.fda.gov
for updates.
Produce Safety
From Production to Consumption: 2004 Action Plan to
Minimize Foodborne Illness Associated with Fresh
Produce Consumption
The
complete action plan can be read at: http://www.cfsan.fda.gov/~dms/prodpla2.html
Goal
and Objectives of the Produce Safety Action Plan (Action Plan):
The
overarching goal of FDA's Action Plan is to minimize the incidence of foodborne illness associated with the consumption of fresh
produce. To achieve this goal, the Action Plan has four general objectives:
1)
Prevent Contamination of Fresh Produce with Pathogens;
2)
Minimize the Public Health Impact When Contamination of Fresh Produce Occurs;
3)
Improve Communication with Producers, Preparers, and Consumers about Fresh
Produce; and
4)
Facilitate and Support Research Relevant to Fresh Produce. For each objective,
FDA's Action Plan identifies steps that could contribute to the achievement of
the objective.
FDA
believes that the most effective strategy for reducing foodborne
illness from fresh produce is one that approaches the problem from several
different angles. For this reason, the Action Plan anticipates that FDA's food
safety partners in both the public and private sectors will participate in the
identified activities. By working both independently and cooperatively, these
agencies or groups will ensure maximum progress toward the goal of reducing the
incidence of foodborne illness associated with the
consumption of fresh produce.
Crop Report by Brad Bergefurd
Pumpkin, gourds, Indian Corn and winter
squash harvest continues between rains and muddy field conditions. Some areas
in