Chapter 11 Food safety

Biological hazards to food

food intoxication or poisoning, food infection and toxin mediated infection

How food might get contaminated

production, processing, distribution, preparation

The burden of Foodborne illness in the U.S.

-2011, CDC estimates annually 1 in 6 Americans (48 million) get sick, 128,000 are hospitalized, & 3,000 die of foodborne diseases, 80% of the disease was from unidentified pathogens **76 million estimated in 1999, but the proportion of Norovirus illnesses estimated to be actually foodborne went down -9.4 million (20%) of the illnesses were caused by 31 known foodborne pathogens & 91% of these foodborne illnesses with the pathogen identified were caused by: **Norovirus (58%), Salmonella nontyphoidal (11%), Clostridium perfringens (10%), Campylobacter sp. (9%), Staphylococcus aureus (3%) -Salmonella was the leading cause of hospitalization (35% of cases) and death (28% of cases)

Variant Creutzfeldt-Jakob Disease (vCJD)

-A rare & fatal human neurodegenerative condition where brain tissue develops holes & has a sponge-like texture. Due to a prion, an infectious misfolded protein that replicates by converting properly folded proteins to misfolded -Most likely caused by exposure to Bovine Spongiform Encephalopathy (BSE) "Mad Cow Disease" prion, most plausibly when people eat meat products contaminated with mad cow disease prion -There has never been a case of vCJD in a country without a history of BSE -1997, U.S. Food & Drug Administration (FDA) banned the use of ruminant (cattle, sheep, goat) tissue in ruminant feed, which is likely responsible for BSE outbreaks

E. coli hemorrhagic colitis

-Escherichia coli O157:H7 is associated with fecal contamination of food -symptoms: non-bloody diarrhea in 1-5days, then bloody diarrhea, severe abdominal pain and dehydration. in young children, hemolytic uremic syndrome (HUS) can lead to kidney failure and death. In adults, may lead to thrombocytopenic purpura (TPP) with cerebral nervous system deterioration, seizures and strokes. -ground beef is most associated food, other foods: raw milk, unpasteurized apple juice and cider, dry-cured salami, homemade venison jerky, sprouts, lettuce, spinach, and untreated water. infected food handlers and infected diapered infants help spread the bacteria -prevent: was row foods, thorough cooking of raw animal products, and avoid recontamination of cooked meat with raw meat. cook ground beef to 155F

Food regulation in U.S

-Food and Drug Administration (FDA) has jurisdiction over all food, except for meat, poultry, & egg products, which fall under the jurisdiction of the US Department of Agriculture (USDA) Food Safety and Inspection Service (FSIS) -FDA promotes science-based food safety principles in retail and foodservice by providing a model Food Code a guide for states & other agencies to develop or update their own food safety rules -Each State has its own public health authorities that oversee food safety -3,000 State, local & tribal agencies have primary responsibility to regulate retail food & foodservice, they are responsible for the inspection of over 1 million food establishments - restaurants, grocery stores, cafeterias, health-care facilities, schools, & correctional facilities

HACCP

-Hazard Analysis & Critical Control Point - a 7 step system to prevent food hazards from occurring: -#1 - Identify the significant food hazards likely to occur e.g. raw ground beef may have pathogens -#2 - Identify critical control points at which the hazard can be controlled e.g. cooking ground beef -#3 - Identify critical limits for each critical control point e.g. cook ground beef to minimum 155 F -#4 - Monitor the critical limits of critical control points e.g. check the cooked temperature periodically -#5 - Establish corrective actions if critical limit not met e.g. discard ground beef not meeting min. temp. -#6 - Verify the system is working e.g. no complaints of food borne illness due to ground beef -#7 - Record keeping to document what has been done

Campylocbateriosis

-Infection of Campylobacter jejuni bacteria -Sources: intestinal tracts of healthy animals (especially chickens), raw & inadequately cooked foods of animal origin are the most common sources of infection (e.g. raw milk, undercooked chicken, hamburger, or fish) -C. jejuni grows best in a low oxygen environment, easily killed by heat (120 F), inhibited by acid, salt & drying, & will not multiply below 85 F -Symptoms: diarrhea, nausea, muscle pain, & fever onset in 2 - 5 days after eating contaminated food. Duration 2 - 7 days, but can be weeks with complications such as urinary tract infection & arthritis -Preventive measures include pasteurizing milk; cooking raw meat, poultry and fish; & preventing cross-contamination between raw & cooked or ready-to-eat foods

Listeriosis

-Listeria monocytogenes is frequently carried by humans and animals, grows at refrigeration temperatures (between 34 F and 113 F), grows from pH 4.1 to 9.6, is salt tolerant, resists drying, but easily destroyed by heat -In healthy, non-pregnant person, listeriosis may occur as a mild illness with fever, headaches, nausea & vomiting -Primarily affects the immune-compromised, newborn or pregnant, intrauterine or cervical infections may result in spontaneous abortion or still birth. Infants born alive may develop meningitis. Mortality rate is 20 to 35% -Incubation period is a few days to several weeks. Foods associated: raw milk, soft cheeses made with raw milk, and raw or refrigerated ready-to-eat meat, poultry or fish -Prevent by: good sanitation, keep refrigerated ready-to-eat foods no longer than 7 days & then discard, pasteurize milk, & cook foods thoroughly

Salmonellosis

-Salmonella bacteria infecting the intestines, often associated with eating eggs, poultry, meats, or fish -Spread by contact with intestinal contents or excrement of animals & humans e.g. spread to food by hands not washed after using the toilet; spread to raw meat during slaughter, is important to make sure hands & working surfaces are thoroughly washed after contact with raw meat, fish & poultry and before working with foods that require no further cooking e.g. salad -Salmonella bacteria grow between 41 - 113 degrees F, destroyed by cooking to 160 F, do not grow at refrigerator or freezer temperatures, but survive & begin to grow again if warmed to room temperature -Symptoms include diarrhea, nausea, chills, fever & vomiting 12 - 36 hours after eating contaminated food, may last 2 - 7 days. Arthritis may follow 3 -4 weeks later

Natural toxins in food

-Saxitoxin - potentially fatal neurotoxin made by algae, shellfish filter & accumulate it, symptoms start in ~ 1 hour after consumption of contaminated shellfish (e.g. mussels), can cause Paralytic Shellfish Poisoning with numbness, drowsiness, possible respiratory paralysis or Amnesic Shellfish Poisoning with confusion, memory loss, possible coma -Mushroom poisoning caused by consumption of raw or cooked mushrooms, most commonly when hunters of wild mushrooms misidentify & consume a toxic species, protoplasmic poisons (cause cell destruction) are most likely to be fatal e.g. Amanita sp. poison causes organ damage, results in 50-90% mortality -Aflatoxin - made by Aspergillus fungi, may damage the liver & cause liver cancer, grow mainly on stored grains (e.g. corn) & legumes (e.g. peanuts) under moist conditions

Hepatitis A virus

-Spread primarily through food or water contaminated by stool from an infected person (fecal - oral route) -Sources: raw or undercooked shellfish e.g. oysters from contaminated waters, raw produce, contaminated drinking water, uncooked foods & cooked foods not reheated after contact with an infected food handler -Incubation period averages 28 days before diarrhea, dark urine, jaundice, fever, headache, nausea, & abdominal pain -Preventable by vaccination: -Vaccination recommended for all children age 12 months & older -Adults vaccinated if exposed to a person infected with hepatitis A, or if planning to travel to a country with high rates of hepatitis A

Staphylococcal intoxication

-Staphylococcus bacteria are found on the skin, in the nose and throat of most people; those with colds and sinus infections are often carriers. Infected wounds, pimples, boils and acne are rich sources. -Staphylococcus grows in warm food and produces toxin, not detectable by taste or smell. The bacteria is killed at 120F, but the toxin is heat resistant -Symptoms include abdominal cramps, vomiting, severe diarrhea 1 to 8 hours after eating, lasting 1 to 2 days. -prevent contamination by good hygiene: hand washing, cover wounds, cover coughs and sneezes, don't prepare food if sick. Keep food out of TDZ during serving and quickly refrigerate or freeze leftovers. -Associated foods: frequently handled, protein rich foods e.g. ham, meats, tuna, chicken, sandwich fillings, cream fillings, potato and meat salads, custards, milk products

Potentially Hazardous Foods (PHF)

-Support the rapid & progressive growth of infectious or toxigenic microorganisms, foods that require time-temperature control to keep them safe for human consumption -A PHF is a food that: **Contains moisture - has a water activity greater than 0.85 (water activity is a measure of the availability of water to microbes e.g. pure water has a water activity of 1.0) **Contains protein **Is neutral to slightly acidic -pH between 4.6 - 7.5 -Examples: milk & dairy products, eggs, meat, poultry, fish and shellfish, baked potatoes, heat-treated plant foods (rice, beans, and vegetables), tofu and other soy proteins, sprouts & sprout seeds, sliced melons & cut tomatoes

The cost of foodborne illness in the U.S

-The estimated annual cost of the health burden of foodborne illnesses in the U.S. is ~ $152 billion, ~ $39 billion can be attributed to produce (fruits, vegetables) alone -Includes: **Medical costs (physician services, pharmaceutical products, and hospitalization) **Losses to quality of life (lost life expectancy, pain and suffering, and functional disability) -average cost of $1,850 each time someone gets sick from food -Consumers are spending $85 billion on the consequences of unsafe food for every $1 billion the government is spending to prevent it

Parasitic worms (helminths) in food

-Trichinella spiralis is an intestinal roundworm whose larvae may migrate from the digestive tract and form cysts in various muscles of the body. Infections due to consuming raw or undercooked pork or wild game. Cook pork & wild game to minimum internal temperatures of 145 °F, & 165 °F, respectively -Taenia saginata (beef tapeworm) and Taenia solium (pork tapeworm), the reproductive cycle, egg production by the organisms, occurs only within humans.Eggs are passed in human feces & may be shed into the environment for as long as the worms remain in the intestines (for as long as 30 years). Eggs may remain viable in the environment for many months. Prevalent in underdeveloped countries with unsanitary conditions & pork or beef are consumed raw or undercooked

time and temperature

-Two of the most important factors to control in the prevention of a food borne illness. -Pathogens grow well in PHFs held between 41 degrees F to 135 degrees F, this range is known as the Temperature Danger Zone (TDZ) -The less time foods spend in the TDZ, the less time pathogens have to grow -Typically, pathogens can grow to levels high enough to cause illness within 4 hours if they are within the TDZ -The more times food goes through the TDZ, the more likely it can have pathogen growth e.g. meat may go from being frozen, into the TDZ to be thawed & cut up to berefrigerated, then back into the TDZ for cooking, then back into the TDZ to be re-refrigerated as leftovers, no reserving of leftovers (are leftovers only once

Clostridium botulinum

-an anaerobic, spore-forming bacteria found in the soil, when growing in the vegetative state forms neurotoxin that if ingested causes botulism -symptoms: in 12-72 hours, descending paralysis starting with double vision, blurred vision, slurred speech, difficulty swallowing, without anti-toxin treatment respiratory paralysis has up to 65% mortality -most botulism is due to improper canning e.g. home or commerical, also fermenting fish, baked potatoes in aluminum foil and foods held warm for extended periods. -infant botulism, associated with eating honey with spores, infants lack microbes to compete with C. botulinum in their intestines, spores germinate and release neurotoxin in intestines, become constipated, lethargic, muscle weakness, progresses to paralysis -boiling food for 10minutes deactivates the toxin

Clostridium perfringens

-an anerobic bacteria, becomes a spore (protected form) when environmental conditions are harsh, spores are found in soil and intestinal tracts of animals and humans -spores survive boiling for 4 or more hours, cooking creates an anaerobic environment, kills off competitive organisms and heat-shocks the spores to germinate to vegetative cells that grow in warm, moist, protein-rich food with little to no oxygen e.g. stews, gravies, meats -infections often occur when food are prepared in large quantities and kept warm (in TDZ) for long periods e.g. cooling on the counter. outbreaks linked to institutions (e.g. hospitals, school cafeterias, prisons, nursing homes) or catered food. -symptoms in 8-24hours, diarrhea and abdominal cramps (not fever or vomiting)usually last 1-2 days. -prevent: rapid cooling e.g. stir hot pot in ice water bath

Shigellosis (Bacillary Dysentery)

-caused by shigella bacteria, present in the stools of infected persons while they are sick and for up to 2 weeks afterward, some persons infected are asymptomatic and still pass the bacteria to others -sources: contaminated food or water, or contact with an infected person. Outbreaks most associated with salads and sandwiches involving a lot of hand contact in preparation and raw vegetables contaminated in the field -infection occurs usually 1-3days, sudden abdominal crampign, fever, diarrhea that may be bloody or contain mucus -commonly seen in child-care settings, toddlers (2-4) are the most likely to get shifellosis, need to wash hands after changing diapers and disinfect changing area -frequent and careful handwashing with soap prevents shigella spread from infected persons to others

Norovirus (aka Norwalk)

-noroviruses spread person to person, by contaminated food or water or surfaces. the leading cause of foodborne-disease outbreaks in U.S. -symptoms, acute gastroenteritis: stomach pain, diarrhea or vomiting multiple times per day. most get better within 1-2days, but may be dehydrated, highly contagious from moment of feeling ill to at least 3 days and up to 2 weeks after recovery, spreads rapidly in closed environments e.g. daycares, nursing homes, hospitals, schools, camps, cruise ships and banquets. -prevent: handwashing after using the toilet, changing diapers and before eating or preparing food. no food handing until after 3 days after recovery. wash fruits and vegetables, thoroughly cook oysters and shellfish -clean up vomit or diarrhea from surfaces with 5-25 tablespoons of household bleach to 1 gallon of water

Moisture

PHF has a water activity of >0.85 or equal to, so reducing water activity to <0.85 or making water less available reduces growth of pathogens -drying food e.g. beef jerky -freezing food -adding solutes e.g. adding salts helps preserve meat

Physical hazards

are foreign objects which are not a part of food, never was meant to be food, but somehow got into the food. -examples: pieces of glass or metal, toothpicks, cigarette butts, pebbles, hair, staples, jewelry

Chemical hazards

are harmful substances such as: pesticides, machine oils, cleansers and cleaning solutions, sanitizers, dissolved metals and excessive amount of a food additive

The 3 types of food hazards

biological, chemical, physical

Biological hazards

cause the most food borne illness outbreaks and are of the greatest concern to food service managers and health inspectors -examples: disease-causing bacteria, viruses, parasites, molds, yeast and naturally occurring toxins

processing

changing plants or animals into food -e.g. by using contaminated water or ice to wash, pack or chill fruits or vegetables, by failure to wash or chill

preparation

getting food ready to eat -e.g. by using the same knife to cut raw chicken, the (without washing it) to slice tomatoes, by food handlers not washing their hands after using the restroom

production

growing and harvesting plants, raising animals -e.g. plants may be contaminated by irrigating with contaminated water, by excess animal manures or pesticides

Toxin mediated infection

infection & toxin produced within the host e.g. Clostridium perfringens, Shigella, Escherichia coli 0157:H7

Factors of control to prevent foodborne illness

moisture, pH adjustment, and oxygen adjustment

Oxygen adjustment

most foodborne pathogens are aerobic, removing oxygen prevents aerobic microbe growth e.g. canning, vacuum packaging -exception: some pathogens, e.g. Clostridium botulinum, the source of botulism, are anaerobic and do not require oxygen to grow

distribution

moving food to the consumer -e.g. refrigerated food left on the loading dock for long time in warm weather and warms enough for bacterial growth

Food infection

reaction to pathogen reproduction in the body after consuming them in food, symptoms often occur in days including diarrhea, stomach cramps, fever & chills (fever and chills are rarer in an intoxication), is often an attack on the intestines e.g. Salmonella, Campylobacter jejuni, Listeria monocytogenes, Norwalk Viruses, & Hepatitis

food intoxication or poisoning

reaction to toxins consumed on food that were produced by bacteria growing on the food (prior to being eaten), symptoms occur rapidly e.g. minutes to hours & often include nausea and vomiting (body trying to rid itself of poison) e.g. Staphylococcus aureus and Clostridium botulinum

pH adjustment

to <4.5 prevents most pathogens growth -e.g. acidifying food (e.g. adding inorganic acids) helps preserve them