P1: SFK/UKS BLBS102-c41 P2: SFK BLBS102-Simpson March 21, 2012 14:25 Trim: 276mm X 219mm Printer Name: Yet to Come Part Food Safety and Food Allergens 785 P1: SFK/UKS BLBS102-c41 P2: SFK BLBS102-Simpson March 21, 2012 14:25 Trim: 276mm X 219mm Printer Name: Yet to Come 41 Microbial Safety of Food and Food Products J A Odumeru Preface Introduction Shelf Life of Foods and Food Ingredients and Food Safety Categories of Foodborne Organisms Sources of Foodborne Pathogens Foodborne Disease Cases and Outbreaks Foodborne Bacterial Infections Campylobacter Enteritis Salmonellosis Listeriosis Verotoxigenic Escherichia coli (VTEC) Infections Foodborne Parasite Infections Foodborne Fungi Foodborne Virus Infection Emerging Pathogens and Food Safety Control Measures for Microbial Contaminants Food Safety Programs Future Perspectives on Food Safety References PREFACE Globally, food safety issues are of top priorities to the food industry, government food safety regulators, and consumers as a result of a significant increase in the number of foodborne disease cases and outbreaks reported worldwide in the twentieth century These issues led to the proliferation of several food safety programs designed to reduce the incidence of foodborne illness Although a number of producers and processors have implemented a variety of food safety programs, the occurrence of foodborne illness from emerging and existing pathogens remains a challenge to the food industry and food safety regulators Food safety begins on the farm and continues through processing, transportation, and storage until the food is consumed Food safety programs such as Good Manufacturing Practices (GMP), Sanitation, Food Quality, and Safety Tests, and Hazard Analysis Critical Control Points (HACCP) are examples of food safety programs that are commonly used to control and monitor microbial contamination of food The three main categories of food safety concerns in the food industry include microbiological, chemical, and physical hazards The microbiological hazards are those involving foodborne pathogens; chemical hazards include concerns related to antibiotics, pesticides, and herbicides; and physical hazards are those related to foreign objects in foods that can result in injury or illness when consumed with foods Although this chapter addresses issues related to microbial hazards, food safety programs, which provide protection against these three types of hazards, especially during food processing, will be discussed Foodborne organisms, sources of microbial contamination of foods and emerging pathogens, will be reviewed in relation to food safety issues INTRODUCTION Food safety concerns are currently at an all-time high due to worldwide publicity about cases and outbreaks of foodborne illness These concerns are now of top priority in the political and economic agendas of governments at various levels One of the worst nightmares for food producers or processors is to have the name of their company show up in a news report as the source of a foodborne illness Apart from the loss of consumer confidence and loss of sales, there are also legal aspects about which food companies must be concerned (Odumeru 2002) An estimated 76 million cases of foodborne illness per year occur in the United States, resulting in 325,000 hospitalizations and 5000 deaths (Mead et al 1999) The economic impact of these illnesses is estimated at $5 billion or more A number of food safety programs are currently in place in the food industry in an attempt to reduce the incidence of foodborne illness, which has been on Food Biochemistry and Food Processing, Second Edition Edited by Benjamin K Simpson, Leo M.L Nollet, Fidel Toldr´a, Soottawat Benjakul, Gopinadhan Paliyath and Y.H Hui C 2012 John Wiley & Sons, Inc Published 2012 by John Wiley & Sons, Inc 787 P1: SFK/UKS BLBS102-c41 P2: SFK BLBS102-Simpson 788 March 21, 2012 14:25 Trim: 276mm X 219mm Printer Name: Yet to Come Part 8: Food Safety and Food Allergens the rise in the last two decades (Maurice 1994) The increase in the incidence of foodborne disease has been attributed to a combination of factors These include changes in food production and processing practices, changes in retail distribution, social changes including consumer preferences and eating habits, lack of experience of mass kitchen personnel, changes in population demographics, and increases in population mobility worldwide as a result of increases in international trade and travel (McMeekin and Olley 1995, Baird Parker 1994) Furthermore, advances in sciences in the area of analytical methods development has led to the availability of better detection methods for the diagnosis of foodborne illness and a subsequent increase in the number of cases reported Other factors such as better reporting systems and increases in the occurrence of emerging pathogens have contributed to the increase in cases of foodborne diseases reported Issues related to emerging pathogens will be discussed in a subsection of this chapter A number of scientific tools are now available to the food industry and food safety regulators for implementing food safety programs designed to reduce the incidence of foodborne illness These include the use of risk assessment of foods and food ingredients, to determine the risks associated with various types of foods under certain processing conditions; predictive modeling, which estimates the growth and survival of pathogens and spoilage organisms under specified conditions; and rapid methods for screening foods for quality and safety during and after production This chapter will provide an overview of issues related to microbial safety of food and food products, food preservation technologies, emerging pathogens, food safety programs to control microbial contamination, and future perspectives on food safety SHELF LIFE OF FOODS AND FOOD INGREDIENTS AND FOOD SAFETY The shelf life of a food product generally refers to the keeping quality of the food An estimated 25% of the food supplies worldwide are lost as a result of spoilage; hence, it is economically beneficial to maintain the quality of food products at various stages of food production and storage There are two categories of foods in relation to shelf life: shelf stable and perishable Whether a particular food product is shelf stable or perishable depends on the intrinsic properties of the food (e.g., pH, water activity, and structure) Shelf-stable foods usually have low water activity, low pH, or a combination of both, while perishable foods tend to have high water activity and high pH The structure or texture of the food is also an important factor in shelf stability Extrinsic factors such as storage temperature, gaseous atmosphere, and relative humidity also determine the shelf stability of food products (McMeekin and Ross 1996) These intrinsic and extrinsic factors influence the survival and growth not only of spoilage organisms but also of pathogenic organisms in foods Food spoilage occurs as a result of physical or chemical changes in the food or of the by-products of spoilage microorganisms growing in the food product Pathogens present in low levels may not produce identifiable changes in the food; hence, the presence of pathogens cannot be determined using noticeable changes in the food as an indicator Although shelf-stable foods are less likely to be implicated in foodborne illness than perishable foods, cross-contamination of shelf-stable or perishable foods by pathogens can be a source of foodborne illness A number of preservation applications used in the food industry are designed to extend the shelf life of the food product by reducing microbial growth; however, pathogens that are able to survive or even grow under preservation techniques such as refrigeration can cause foodborne illness Effective strategies for controlling the presence of spoilage and foodborne pathogens in foods should include elimination of sources of contamination combined with food preservation technologies such as drying, freezing, smoking, curing, fermenting, refrigeration (Baird-Parker 2000) and modified-atmosphere packaging (Farber 1991) CATEGORIES OF FOODBORNE ORGANISMS Microorganisms that can be transmitted to humans or animals through food are referred to as foodborne organisms There are three main categories of foodborne organisms: spoilage, pathogenic, and beneficial Spoilage organisms can grow and produce physical and chemical changes in foods, resulting in unacceptable flavor, odor, formation of slime, gas accumulation, release of liquid exudates or purge, and changes in consistency, color, and appearance Also, extracellular or intracellular enzymes released by spoilage organisms can result in deterioration of food quality Growth of microorganisms to high numbers is usually required before spoilage becomes noticeable Hence, control of growth of spoilage organisms is required to impede microbial spoilage The presence of foodborne pathogens in foods in low concentrations can render foods harmful to humans if consumed Because pathogenic organisms at low levels may not produce noticeable changes in foods, consumers may not have advance warning signals of the danger associated with consumption of contaminated foods “Beneficial” or “useful” organisms include microorganisms used in various food fermentation processes These organisms are either naturally present in such foods or added to produce the desired by-product of fermentation Various types of foods such as fruits and vegetables, pickles, dairy products, meats, sausages, cheeses, and yogurt are common types of fermented products involving the use of beneficial organisms Beneficial organisms include organisms in the group of lactic acid bacteria, yeasts, and molds Bacteria species from 10 genera are included in the group of lactic acid bacteria These include Lactococcus, Leuconostoc, Streptococcus, Lactobacillus, Pediococcus, Carnobacterium, Tetragenococcus, Aerococcus, Vagococcus, and Enterococcus The most important type of yeast used for fermentation of food and alcohol is Saccharomyces cerevisiae This yeast is used for leavening bread and production of beer, wine, and liquors It is also used for food flavor Non-mycotoxin-producing molds from the genera Penicillium and Aspergillus, and some in the Rhizopus and Mucor genera, have been used for beneficial purposes in food preparation (Bibek 1996) P1: SFK/UKS BLBS102-c41 P2: SFK BLBS102-Simpson March 21, 2012 14:25 Trim: 276mm X 219mm Printer Name: Yet to Come 41 Microbial Safety of Food and Food Products 789 Figure 41.1 On-farm sources of microbial contamination of water and food products of plant and animal origin (Adapted from Beuchat 1995.) SOURCES OF FOODBORNE PATHOGENS In order to determine and implement effective control measures for pathogens in foods, it is important to identify potential sources of contamination Plants and animals are the main source of human food supply The exterior and, in some cases, the interior of plants and animals harbor microorganisms from external sources such as soil, water, and air These environmental sources contain a wide variety of microorganisms, some of which are pathogenic to man Contamination of the food supply can occur at various stages of production, processing, transportation, and storage For example, fruits and vegetables can be contaminated at the farm level as well as during harvesting, transportation, and processing Potential sources of on-farm contamination of fruits and vegetables are summarized in Figure 41.1 Meats can be contaminated at the time of slaughter, processing, and storage Microbial contamination can come from slaughtered animals, water, equipment, utensils, the slaughterhouse environment, and workers Thus, intervention strategies to control microbial contamination of the food supply must be implemented at various stages of food production, processing, transportation, and storage, and also at the consumer end of food preparation FOODBORNE DISEASE CASES AND OUTBREAKS Foodborne disease in a susceptible host can result from consumption of food or water contaminated with pathogenic organisms A single or sporadic case of foodborne illness refers to an instance when an illness that is unrelated to other cases occurs as a result of consumption of contaminated food or water An outbreak, on the other hand, refers to an incident in which two or more persons become ill after consuming the same food or water from the same source The occurrence of a foodborne illness depends on a number of risk factors such as (1) type and number of pathogenic microorganisms in the food, (2) effect of food product formulation or processing on the viability of the pathogen, (3) storage conditions of the food that may promote contamination, growth, and survival of the pathogen, and (4) the susceptibility of the individual to foodborne illness It is believed that the number of reported outbreaks represents only 10% of the real incidence of foodborne disease, even in countries with well-established surveillance systems (Baird-Parker 2000) Foodborne illness resulting from severe infections such as hemolytic uremic syndrome, botulism, and listeriosis often require hospitalization and are more likely to be reported, while self-limiting foodborne illness such as salmonellosis, campylobacteriosis, and S aureus enterotoxin–related infections are less likely to be reported It is believed that viral foodborne infections account for a large portion of cases of foodborne illness (Caul 2000) However, the extent of the problem on a global scale is difficult to assess as a result of lack of surveillance data in most parts of the world, coupled with the fact that most viral infections are self-limiting Although viruses and bacteria-related infections account for the majority of foodborne diseases, certain groups of parasites and fungi are also etiologic agents of foodborne diseases Foodborne Bacterial Infections Several types of foodborne bacterial pathogens are implicated in foodborne diseases Examples of bacterial genera most commonly implicated in foodborne infections, onset and duration of the symptoms of the disease, types of foods that are likely to be contaminated by these groups of bacteria, and potential sources of contamination are summarized in Table 41.1 Bacterial pathogens including Campylobacter, Salmonella, Listeria monocytogenes, and verocytotoxigenic E coli are the top causes of bacterial foodborne infections in westernized countries, based on the number of reported cases (Sharp and Reilly 2000) The 12–60 hours Watery diarrhea, abdominal cramps, low-grade fever, nausea, malaise Severe cramping, watery diarrhea becoming bloody, low-grade fever Escherichia coli (Traveller’s diarrhea) E coli O157:H7 790 Listeria monocytogenes A few days to weeks 6–22 hours Days to weeks 2–9 days to weeks Days Under 24 hours, may persist 1–2 weeks Months 2–10 days Diarrheal: 12–24 hours Emetic: 6–24 hours Pregnant woman, immunocompromised persons, cancer and AIDS patients and those with chronic diseases, elderly, (fatality rate is as high as 70%) Children Everyone, but young and elderly are most affected Everyone Everyone Children under five, young adults 15–29 Everyone Target Population Soil, improperly made silage Cattle, deer Water, Human sewage Soil, feces Cattle, chicken, birds, flies, stream, pond water Soil, sediment, intestinal tracts of fish and mammals Soil, Dust Source Undercooked or raw hamburger, raw milk, unpasteurized apple cider Raw milk, soft ripened cheeses, ice cream, raw vegetables, fermented raw meat, sausages, hot dogs, luncheon meats, raw and cooked poultry, raw and smoked fish Dairy products Canned foods, smoked and salted fish, chopped bottled garlic, saut´eed onions, honey Meats, meat products, poultry, gravy Raw chicken, turkey, raw milk, beef, shellfish, water Diarrheal: meat, milk, vegetables, fish, soups Emetic: rice products, potatoes, pasta, cheese products Suspect Foods Trim: 276mm X 219mm Septicemia, maningoen cephalitis, spontaneous abortions, stillbirths, influenza-like symptoms 1–3 days Diarrhea, cramps, nausea (vomiting rare) 18–36 hours, varies hours to days Clostridium perfringens Clostridium botulinum 2–5 days Diarrheal: 6–15 hours Emetic: 30 minutes to hours Duration 14:25 Diarrhea (may contain blood), fever, nausea, vomiting, abdominal pain, headache, muscle pain Fatigue, weakness, double vision, respiratory failure Diarrheal illness including abdominal cramps, nausea (vomiting rare) Emetic illness including nausea and vomiting Two forms: Onset March 21, 2012 Campylobacter jejuni Bacillus cereus (B cereus) Symptoms P2: SFK BLBS102-Simpson Organism Table 41.1 Foodborne Bacterial Pathogens, Symptoms of Disease, Target Populations, and Potential Sources of Food Contamination P1: SFK/UKS BLBS102-c41 Printer Name: Yet to Come ... Safety of Food and Food Products J A Odumeru Preface Introduction Shelf Life of Foods and Food Ingredients and Food Safety Categories of Foodborne Organisms Sources of Foodborne Pathogens Foodborne... pathogens, food safety programs to control microbial contamination, and future perspectives on food safety SHELF LIFE OF FOODS AND FOOD INGREDIENTS AND FOOD SAFETY The shelf life of a food product... Safety of Food and Food Products 789 Figure 41.1 On-farm sources of microbial contamination of water and food products of plant and animal origin (Adapted from Beuchat 1995.) SOURCES OF FOODBORNE