Jongen Improving the Safety of Fresh Fruit and Vegetables

1. Auflage 2005
ISBN: 978-1-84569-024-3
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, 656 Seiten

Reihe: Woodhead Publishing Series in Food Science, Technology and Nutrition

Fresh fruit and vegetables have been identified as a significant source of pathogens and chemical contaminants. As a result, there has been a wealth of research on identifying and controlling hazards at all stages in the supply chain. Improving the safety of fresh fruit and vegetables reviews this research and its implications for food processors.Part one reviews the major hazards affecting fruit and vegetables such as pathogens and pesticide residues. Building on this foundation, Part two discusses ways of controlling these hazards through such techniques as HACCP and risk assessment. The final part of the book analyses the range of decontamination and preservation techniques available, from alternatives to hypochlorite washing systems and ozone decontamination to good practice in storage and transport.With its distinguished editor and international team of contributors, Improving the safety of fresh fruit and vegetables is a standard reference for all those involved in fruit and vegetable production and processing. - Reviews recent research on controlling hazards at all stages of the supply chain - Discusses the implications of this research on food processors - Discusses the implications of this research on food processors

Autoren/Hrsg.

Jongen, Wim

Leseproben

2 Pathogens in fruit
Y. Zhao    Oregon State University, USA 2.1 Introduction
Fresh fruit and processed fruit products have generally been considered safe from pathogenic bacteria because of their high acid content. However, recent outbreaks of E. coli O157:H7 and Salmonella spp. in apple and orange juices have challenged the belief that high acid foods cannot harbor viable pathogenic bacteria. Owing to the acidic similarity of berry juice (pH 3.0–4.5), apple juice (3.0–4.0) and orange juice (3.0–4.0), there is concern that fruit juices could also act as a vector for foodborne illness. Laboratory studies have determined that berry juices and purées can support bacteria such as E. coli O157:H7 and Salmonella spp. (Fig. 2.1). These findings suggest that berries and berry products, if contaminated, might harbor pathogenic organisms long enough to cause foodborne illnesses. Fig. 2.1 Survival of E. coli in fruit juices and puree. adapted from Bower et al., 2003 Figure 2.2 illustrates the potential sources and vectors of contamination of the fruit during production and processing, as well as the potential foodborne pathogens. A major source of microbial infection is introduced through contaminated water used on fresh produce during growth, harvesting and processing. Water can be a carrier of pathogenic bacteria (e.g. E. coli, Salmonella spp., Vibrio cholerae, Shigella spp.), protozoa (e.g. Cryptosporidium parvum, Giardia lamblia, Cyclospora cayetanensis, Toxiplasma gondii), mycotoxin-producing fungi and viruses (e.g. Norwalk and hepatitis A). If these organisms are accidentally consumed, even in small amounts, illness can result. Another significant source of pathogens arises from unsanitary field conditions. Cattle manure and the feces of sheep and deer may harbor E. coli O157:H7, resulting in contamination of fresh produce during harvesting. Improper worker hygiene may also spread Salmonella, Cryptosporidium and other pathogens through human fecal matter. Some major concerns about pathogens in fruit are briefly described in the following paragraphs and summarized in Table 2.1. Fig. 2.2 Potential contaminations of fruit during production and processing. adapted from Bower et al., 2003 Table 2.1 Illness caused by the most concerned microbial infections in fresh produce E. coli 0157:H7 • First recognized as human pathogen in 1982 • Outbreaks often associated with undercooked ground beef • Outbreaks have involved lettuce, unpasteurized apple cider and juice, radish sprouts and alfalfa sprouts • Naturally exists in animals without symptoms – cattle. sheep. deer, dogs, cats. other animals • Can contaminate/grow on fresh produce in minimally processed cantaloupe, watermelon cubes, shredded lettuce, sliced cucumbers and mesclun lettuce • Wild or domestic animals • Improperly composted animal manure • Fruits and vegetables dropped on ground contaminated by manure • Water may carry and spread organisms • Farm and packing house workers, any food handlers, may contaminate produce • Severe cramps, bloody diarrhea, vomiting, dehydration • Severe complications can include kidney failure, strokes, seizures and sometimes painful death • Onset 3–9 days; lasts 2–9 days, unless there are complications Salmonella species • Comes from intestinal tracts of poultry, pigs, birds, and insects • Can be carried by humans • Infective dose – a few cells to millions • Isolated from many types of raw fruits and vegetables – not a frequent event • Outbreaks linked to tomatoes. bean sprouts, melons and unpasteurized orange juice and apple juice • Similar to E. coli • Nausea, vomiting, abdominal cramps, diarrhea. fever, and headache • Symptoms occur in 12–48 hours and last 2–6 days in otherwise healthy people • May last weeks in immunocompromised people • Secondary problems such as reactive arthritis or pericarditis may result in some patients L. monocytogenes • Widely distributed in nature – in soil, sewage, fresh water sediments – in silage, decaying plant matter – in animal intestinal tracts • Animal carriers may not be sick • Found in raw foods – meats, unpasteurized milk – vegetables • Common environmental contaminant • Unlike most microorganisms it grows at refrigeration temperatures • Floor drains and wheel condensate collects are frequent sources of contamination • Flu-like symptoms in healthy people • May progress to meningitis, blood poisoning, abortion in pregnant women or death • Symptoms appear within 1 day to 3 weeks • Duration depends on treatment • High fatality rate in immune- compromised individuals Virus – hepatitis A • Excreted in feces be infected individuals • Can be carried by raw produce, uncooked food • Persists for weeks or months on crops or soils • Hepatitis A on lettuce, raspberries and strawberries • Viruses can be transmitted to plants and fresh fruits and vegetables by people, tractors, equipment, clippers and insects • Viruses can cause plant and animal diseases • Causes fever, nausea, vomiting, abdominal cramps, extreme fatigue, jaundice • Onset 15–50 days after ingestion • Lasts 1–2 weeks to months in severe cases Source: Adapted from Bower et al., 2003. 2.1.1 Escherichia coli
Enterohemorrhagic E. coli O157:H7 is recognized as an important foodborne pathogen and grows rapidly in several types of raw fruits and vegetables, particularly when stored at 12 °C. The infection dose of E. coli O157:H7 is low and can develop acid resistance. Since cattle appear to be a primary reservoir, the vast majority of outbreaks of illness associated with E. coli O157:H7 have been associated with consuming undercooked beef and dairy products. However, outbreaks have also been linked to lettuce, unpasteurized apple cider, cantaloupe and sprouts. In outbreaks associated with cantaloupe and in some cases lettuce, contamination, particularly with raw beef juices, occurred during final preparation. 2.1.2 Salmonella
The genus Salmonella has over 2700 serotypes. Surveys of fresh produce have revealed the presence of several Salmonella serotypes capable of causing human infection. Animals and birds are the natural reservoirs. Poultry and other meat products, eggs and dairy products, are the most commonly implicated sources in salmonellosis outbreaks. Fresh fruit and vegetables are implicated less frequently, although outbreaks have been documented most notably in cantaloupe and sprouts. Several additional large outbreaks of salmonellosis have been attributed to fresh produce. Among them are three multi-state outbreaks traced to the consumption of raw tomatoes: one involved Salmonella Javiana in 1992, another involved Salmonella Montevideo in 1993 and a...