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Food safety Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Why is Food Safety Important? Food-borne illness: symptoms or illness from food or water that contains an infectious agent, poisonous substance, or protein causing an immune reaction. • 76 million people report food-borne illness • each year. Many more cases go unreported. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Why is Food Safety Important? • Food spoilage can be from enzymes naturally • • found in the food or from microbes that colonize the food. Processed foods can spoil just as fresh meats, fruits, and vegetables do. Three factors most often responsible are: (1) oxygen (2) light (3) heat Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Why is Food Safety Important? • Food producers may use chemicals, drugs, or • • • other substances to manipulate food products. Food additives: chemicals added to enhance foods. Food preservatives: chemicals added to food to maintain freshness and appearance. Pesticides: family of chemicals used in both the field and storage areas to decrease plant, fungal and animal pests. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Government Regulators Multiple government agencies are involved in ensuring the safety and quality of the food supply: • States Department of Agriculture (USDA) • U.S. Food and Drug Administration (FDA) • Centers for Disease Control and Prevention • (CDC) Environmental Protection Agency (EPA) Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Causes of Food-Borne Illness Food infections: illness resulting from eating food contaminated with living organisms. Food intoxications: illness resulting from eating food in which microbes have secreted toxins (poisons). Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Causes of Food-Borne Illness Bacteria are the most common microbes causing food-borne illnesses. Of the bacteria, the most common food contaminants are: • Campylobacter jejuni • Salmonella Also, Listeria monocytogenes, Shigella, Vibrio Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Causes of Food-Borne Illness Campylobacter jejuni Campylobacteriosis: •Diarrhea •Cramping •Abdominal pain •Fever withing 2-5 days post-exposure Commonly found in chickens, also cow’s udders More than ½ of raw chicken in the US market has Campylobacter on it Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Salmonella Salmonellosis •Diarrhea •Abdominal cramps •Fever 12-72 hours postinfection •Infection may last 4-7 days Salmonella live in the intestinal tracts of humans and other animals Credit Rocky Mountain Laboratories, NIAID, NIH Salmonella invading cultured human cells Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Foods of animal origin may be contaminated: raw eggs, unpasteurized milk and raw meat, also unwashed produce Causes of Food-Borne Illness Other microbes causing illness include • Viruses such as hepatitis A, hepatitis E, • • • Norwalk virus Helminths or worms, such as tapeworms, flukes, and roundworms. Giardia, causing a diarrheal illness called giardiasis Fungi causing food spoilage Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hepatitis E Drs. E.M. Kraan a, dr. M. Koopmans b, dr. P.M. Schneeberger c, Fataal verlopen infectie met in Nederland verworven hepatitis E virus bij een patiënte met een vermoedelijk hepatocellulair carcinoom Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Parasitic worms Credit: Red Book Online, American Academy of Pediatrics Brain scan of pork tapeworm Taenia tolium Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Toxoplasma gondii • Parasite • Modes of transmission: (1)consumption of raw foods (2)Fecal-oral route (3)Mother to fetus (4)Blood transfusion (rare) Credit: Image provided by Ke Hu and John Murray Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Giardia SEM image: Content Providers(s): CDC/ Janice Carr Credit: Public Health Image Library Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Causes of Food-Borne Illness Some microbes cause illness by secreting poisons called toxins. • Clostridium botulinum produces botulism toxin • • which blocks nerve transmissions to muscle cells. Mycotoxins are secreted by fungi. Toxins can be neurotoxins or enterotoxins. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Food Allergies • Allergic reactions to food may include • • symptoms such as rashes, headaches, or bowel disturbances. The foods that most often cause allergic reactions include cow’s milk, eggs, nuts, citrus fruit, seafood, wheat, corn, soy. Most food allergies are reactions to proteins contained in the food. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Food Allergies • Some food allergies are fixed – the reaction • • occurs every time the food is eaten. Some food allergies are cyclic – after 3 to 6 months without the food, it may be slowly reintroduced to the diet with no effect. Many children outgrow early food allergies. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Preventing Food-Borne Illness When preparing foods at home, be sure to • Wash hands and kitchen surfaces often • Separate foods to prevent cross contamination • Cook foods the their proper temperature • Chill foods to prevent microbes from growing Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Preventing Food-Borne Illness Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Preventing Food-Borne Illness • Foods should be cooked thoroughly to kill • • microbes. Leftovers should be stored in the refrigerator for a limited period of time. Food should be thawed slowly in the refrigerator. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Preventing Food-Borne Illness Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Preventing Food-Borne Illness Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Preventing Food-Borne Illness Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Preventing Food-Borne Illness Thoroughly cooking food destroys microbes but toxins may remain in the food. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Preventing Food-Borne Illness When eating out: • Eat at restaurants that look clean • Insist that food be cooked thoroughly When traveling: • Avoid raw foods, salads, uncooked fruits and • vegetables, unpastuerized milk Only drink bottled water or soda, boiled water such as tea, beer, wine Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Preventing Food Spoilage Spoilage can be prevented by many natural techniques: • Salting or sugaring • Drying the food • Smoking • Cooling Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Preventing Food Spoilage More modern techniques include: • Industrial canning • Pasteurization • Chemical preservatives • Irradiation • Genetic modification Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Preventing Food Spoilage Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Food Additives • Natural food additives include beet juice, salt, • • and citric acid. Many other additives are synthetic chemicals added to food. Additives can be used for adding flavor, color, or nutrients to foods. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Food Additives Flavorings: • Flavoring agents such as essential oils or spices • are used to replace flavor lost during processing. Flavor enhancers do not have flavor of their own. • Examples include maltol and MSG Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Food Additives Colorings: • Beet juice (red), beta carotene (yellow), and caramel (brown) are natural coloring agents Vitamins and minerals: • Vitamin E, ascorbic acid (vitamin C), vitamin D, iodine Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Food Additives Other food additives include: • Texturizers, stabilizers, thickening agents, or • • emulsifiers that change the consistency of processed foods Humectants or desiccants that maintain the proper moisture levels Bleaching agents to change the color of food Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Residues on Foods Various chemicals can persist and even accumulate in foods. These residues can include: • Persistent organic pollutants (POPs) • Pesticides • Growth hormones Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Persistent Organic Pollutants Persistent organic pollutants: chemicals released into the atmosphere from industry, agriculture, automobiles, and waste disposal. • Found on virtually all categories of food. • Includes: • Mercury and lead • PCBs • dioxins Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Pesticides Pesticides are used to help protect against crop losses, reduce the incidence of disease, and increase crop yields. • Most common are insecticides, herbicides, • • • fungicides Can be natural or synthetic Can remain as a toxin on foods Regulated by the EPA Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Growth Hormones Recombinant bovine growth hormone (rBGH) is a genetically engineered growth hormone given to cows • Increases muscle mass; decreases fat • Increases milk production • Causes mastitis in cows, resulting in increased • antibiotic use in the cows Risks to humans are still being studied Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Organic Foods Organic foods are grown without the use of synthetic pesticides • Standards for organic production are regulated • by the USDA Benefits of organic foods: • 2.5 times more nutritious • Higher vitamin and mineral content • Lower in toxic metals Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings