Matthews The Produce Contamination Problem

Causes and Solutions
2. Auflage 2014
ISBN: 978-0-12-404686-3
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, 492 Seiten

Reihe: Food Science and Technology

Understanding the causes and contributing factors leading to outbreaks of food-borne illness associated with contamination of fresh produce is a worldwide challenge for everyone from the growers of fresh-cut produce through the entire production and delivery process. The premise of The Produce Contamination Problem is that when human pathogen contamination of fresh produce occurs, it is extremely difficult to reduce pathogen levels sufficiently to assure microbiological safety with the currently available technologies. A wiser strategy would be to avoid crop production conditions that result in microbial contamination to start. These critical, problem-oriented chapters have been written by researchers active in the areas of food safety and microbial contamination during production, harvesting, packing and fresh-cut processing of horticultural crops, and were designed to provide methods of contamination avoidance. Coverage includes policy and practices in the United States, Mexico and Central America, Europe, and Japan. - Addresses food-borne contaminations from a prevention view, providing proactive solutions to the problems - Covers core sources of contamination and methods for identifying those sources - Includes best practice and regulatory information

Autoren/Hrsg.

Matthews, Karl

Leseproben

Chapter 1

Scope of the Produce Contamination Problem

Gerald M.Sapers1Michael P.Doyle2     1Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture (Retired), Wyndmoor, PA     2The University of Georgia, Center for Food Safety, Griffin, GA, USA

Abstract

In recent years, outbreaks of foodborne illness in the U.S. have been attributed with increasing frequency to fresh and fresh-cut fruits and vegetables. Contamination of produce with human pathogens has important public health and economic consequences. U.S. government statistics indicate that the most commonly implicated commodities are green salads and lettuce, other leafy vegetables and herbs, sprouts, tomatoes, melons, fruit salads, and unpasteurized juices. The pathogens most often implicated are norovirus, E. coli O157:H7, and Salmonella spp., although large outbreaks also have been associated with hepatitis A virus, Cryptosporidium, and Cyclospora. While these pathogens have been isolated from fresh produce and the farm environment, the sporadic nature of produce-related outbreaks makes systematic study of contamination sources difficult. Human pathogens can adhere strongly to produce surfaces and form-resistant biofilms or become internalized within pores and at cut surfaces. These factors can reduce the efficacy of cleaning and sanitizing treatments, thereby increasing the risk of contamination. Improvements in produce safety will require better understanding of contamination sources, environmental influences, and agricultural practices affecting pathogen survival and growth. Improved methods of pathogen reduction in contaminated produce are needed. Such information can be incorporated in Good Agricultural Practices (GAPs) and more effective postharvest interventions to reduce the risk of produce contamination.

Keywords

Outbreak characteristicsprevalence of contaminationcontamination sourcespathogen attachment and survivalpostharvest contaminationfresh-cut processing, interventions

Chapter Outline

Introduction

Produce-associated outbreaks—a new problem?

Consequences of produce-associated outbreaks

Key aspects of the produce contamination problem

Characteristics of produce-associated outbreaks

Prevalence of produce contamination with human pathogens

Microbial attachment and survival on produce surfaces

Potential sources of produce contamination

Preharvest sources

Contamination during packing

Contamination during fresh-cut processing

Gaps in our understanding of produce contamination

Current state of knowledge

What we don’t know

Developing effective interventions

Introduction

Produce-associated outbreaks—a new problem?

For decades, concerns regarding the microbiological safety of foods have focused largely on the animal products responsible for outbreaks of E. coli O157:H7 from ground beef; salmonellosis from poultry, meats, eggs, and dairy products; and listeriosis from soft cheeses and processed meats. Outbreaks of botulism were associated with canned vegetables, but fresh fruits and vegetables generally were considered to be safe, except in countries where the combination of endemic gastrointestinal diseases, unsafe agricultural practices, and poor sanitation resulted in traveler’s diarrhea and other illnesses acquired by consumption of locally grown fresh produce. U.S. produce packers and the fresh-cut industry have long believed that their products were made safe by the use of a triple-wash technology using chlorinated water or other approved sanitizing agents.

In recent years, however, this picture has changed dramatically due to an increase in the number of outbreaks of foodborne illnesses associated with fresh and fresh-cut fruits and vegetables. Many large outbreaks, involving widely consumed commodities such as apple cider, cantaloupe melons, raspberries, bagged lettuce and spinach, tomatoes, green onions, and sprouts, have been reported during the past decade (Brackett, 1999; Beuchat, 2002; WHO, 2008). This increase may be due in part to greater consumption of fresh produce in response to the recommendations of health and nutrition professionals. Increased consumption has translated into increased production and distribution of fresh produce, but the growth of produce packing and fresh-cut processing facilities with regional or national distribution capabilities has exposed more consumers to products that may have been contaminated on a single processing line or at a single farm. Additionally, to meet increased demand for out-of-season items, sourcing of fresh produce has become a global endeavor, involving some growing locations where the potential for human pathogen contamination of fruits and vegetables may be high. Furthermore, with better methods for identifying and tracking foodborne outbreaks, the local and state health departments and the Centers for Disease Control and Prevention (CDC) have become better at detecting produce-associated outbreaks, many of which would not have been recognized previously, or the source not identified.

Consequences of produce-associated outbreaks

Pathogen contamination of fresh produce has important public health consequences. Not only are there more cases of illness from produce-associated outbreaks, but highly vulnerable population groups—the very young, the old, and the immunocompromised—are often affected. For these individuals, the severity of foodborne illnesses can be much greater, if not life-threatening, and there may be serious long-term consequences to health. An indirect health-related consequence is the reduced intake of beneficial nutrients from fruits and vegetables by individuals who consume less fresh produce because of concern about acquiring a foodborne illness.

The economic consequences of produce-associated outbreaks are substantial, including the medical costs and lost income of patients, and the costs of damage control (disposal of unmarketable products, product recalls, cleanups, and retrofitting) and lost production time incurred by the affected produce packer/processor. In addition, there are the costs associated with litigation, awards from successful lawsuits, and long-term damage to the company’s reputation, reflected by reduced sales of fresh produce. A history of outbreaks can be damaging to an entire segment of the produce industry (e.g., spinach, lettuce, sprouts, green onions, cantaloupes, and tomatoes) or to a production area (e.g., the Salinas Valley of California), resulting in increased costs for compliance with government-mandated changes in production and processing practices and in reduced sales of products nationwide. The estimated cost to tomato growers from the 2008 multistate Salmonella Saintpaul outbreak (over 1400 cases reported) was approximately $200 million (Anon., 2008). This outbreak was originally attributed to contaminated tomatoes, but subsequent investigation implicated jalapeño peppers as the major vehicle, with serrano peppers also as a vehicle, and tomatoes as a possible vehicle (CDC, 2008a). The overall economic cost to the produce industry could be a generalized reduction in sales and consumption of fresh fruits and vegetables due to reduced confidence in their safety.

Key aspects of the produce contamination problem

Characteristics of produce-associated outbreaks

Data compiled by the CDC provide insight into trends in the prevalence, size, and causes of produce-related outbreaks (CDC, 2000; CDC, 2006a; CDC, 2008b) and the Outbreak Online Database for 2003 to 2010 (CDC, 2012a). Between 1993 and 1997, the prevalence of outbreaks associated with fresh fruits and vegetables, as reported by the CDC in summary tables for each year, was erratic with no upward trend (Table 1.1). However, there was an abrupt increase in the prevalence of produce-associated outbreaks between 1998 and 2002, perhaps in part because of a change in surveillance and/or reporting methodology (CDC, 2006a). Since then, the number of outbreaks has remained at a high level but with considerable fluctuation from year to year. Likewise, the number of cases has fluctuated greatly, often because of the occurrence of a small number of very large outbreaks in a single year. It is not clear yet whether the marked decreases in outbreaks and cases in 2009 to 2010 represent the beginning of a downward trend.

Table 1.1

Number of Reported Foodborne-Disease Outbreaks and Cases Associated with Fruits and Vegetables,...