Transcript Sources of Foodborne Enteric Microbial Contamination

ENVR 430:
Foodborne
Microbial
Disease
And Food
Safety
Brock
Suggested Reading:
Chapter 29 – Food Preservation and
Foodborne Microbial Diseases pp. 950
Simmons 1
Where does your food come from????
Simmons 2
E. coli 0157:H7 Spinach
Date: Tue 19 Sep 2006
Source: FDA.gov
Case Reports:To date, 131 cases of illness due to _E. coli_ infection have
been reported to the Centers for Disease Control and Prevention (CDC),
including 20 cases of Hemolytic Uremic Syndrome (HUS), 66
hospitalizations, and one death.
Illnesses:Illnesses continue to be reported to CDC. This is considered to
be an ongoing investigation.
States Affected:There are 21 confirmed states: California, Connecticut,
Idaho, Illinois, Indiana, Kentucky, Maine, Michigan, Minnesota, Nebraska,
Nevada, New Mexico, New York, Ohio, Oregon, Pennsylvania, Utah,
Virginia, Washington, Wisconsin, and Wyoming.
Simmons 3
California –
another outbreak!!
E. COLI O157, UNPASTEURIZED
MILK - USA (CALIFORNIA)
Date: Fri, 22 Sep 2006
Source: CBS2.com
Tainted milk has infected people with _E. coli_ [O157:H7] bacteria, prompting a recall of
some milk products, health officials said Fri, 22 Sep 2006. Those infected got sick after
drinking unpasteurized milk produced by Organic Pastures, a Fresno County, California
dairy, according to the San Diego County Health and Human Services Agency. An 8-yearold San Diego County girl, a Riverside County boy, 7, and a 10-year-old girl in San
Bernardino County got sick after drinking the contaminated milk. The state has ordered
all Organic Pastures whole and skim raw milk to be pulled immediately from stores and
consumers were encouraged to throw away any of the milk in their refrigerators. The
recall order also affects raw cream and raw colostrum made by the dairy. Organic
Pastures has been prohibited from producing raw milk for the retail market until further
notice, officials said. The _E. coli_ outbreak was limited to raw, or unpasteurized milk,
county health officials said. Most milk consumed in California is pasteurized, which
reduces the risk of getting a bacterial illness.
Simmons 4
Campus Health Alert - Confirmed E. Coli Cases Among UNC Students (11-6-2006)
In recent days, three University students have developed confirmed cases of gastroenteritis caused by E. coli
O157:H7 bacteria. This illness causes severe diarrhea (often bloody), abdominal cramps and is occasionally
associated with severe complications, especially in young children and the elderly. The affected students
developed symptoms between October 26th and 29th. Health authorities are investigating a small number of
additional possible cases among University students. To date, the investigation by public health authorities
has not identified any common source of exposure. Currently, there is no indication that other students are at
risk. These bacteria usually make people sick within 10 days of exposure. The Orange County Health
Department, working in consultation with the North Carolina Communicable Disease Branch, is investigating
all of the cases involving the small number of UNC students. Officials from the University's Campus Health
Services, Department of Environment, Health and Safety and other offices are monitoring the situation
closely and collaborating in the investigation. If you experience severe diarrhea and abdominal cramps, you
are encouraged to seek medical attention immediately.
Following is a sampling of general tips from the Centers for Disease Control and Prevention on how you can
prevent E. coli infection:
1.Washing hands frequently and well is the most important thing you can do to avoid bacterial illness.
2.People with diarrhea should wash their hands carefully with soap after bowel movements to reduce the risk
of spreading infection. Anyone with a diarrheal illness should avoid swimming in public pools, sharing baths
with others, preparing food for others, providing day care or direct health-care services.
3.Cook all meat and eggs thoroughly. You can decrease the risk of illness by not eating raw or undercooked
meat or eggs. Use a digital instant-read meat thermometer to ensure thorough cooking.
4.If you are served an undercooked meat or eggs in a restaurant, send it back for more cooking and ask for a
clean plate.
5.Avoid spreading harmful bacteria in the kitchen. Keep raw meat separate from ready-to-eat foods. Wash
hands, counters and utensils with hot soapy water after they touch raw meat or eggs. Never place cooked
food on the unwashed plate that held raw meat or eggs. Wash meat thermometers in between tests.
6.Wash fruits and vegetables under running water, especially those that will not be cooked. Bacteria are
sticky, so even thorough washing may not remove all contamination. Remove the outer leaves of leafy
vegetables. People at high risk of complications from food-borne illness may wish to eat cooked vegetables
and peeled fruits.
Simmons 5
Two more cases of salmonella reported in N.C.
Posted: Jan 21, 2009
Updated: Mar. 9, 2009
Two more cases linked to national salmonella scare involving peanut butter-based foods have been reported in North Carolina, bringing the
number of cases in the state to six, state health officials said Wednesday afternoon. At least 485 people – 107 of whom were hospitalized – in 43
states and Canada have become ill since August. Six have died, including one person from Catawba County, according to the U.S. Centers for
Disease Control and Prevention. The latest cases in North Carolina are in Onslow and Vance counties; previously reported cases were in
Brunswick, Caldwell and Robeson counties. Among those infected was a 3-year-old child. Three of those patients, including the one who died
in November, had been hospitalized. Meanwhile Wednesday, state scientists were helping to track down the source by looking at companies
that make food with the peanut butter in question.
Joe Reardon, a spokesman for the North Carolina Department of Agriculture and Consumer Services said microbiologists were testing an
additional 51 samples of peanut butter products from a Kellogg's cracker plant in Cary to determine if the facility is contaminated by the
bacteria. The Kellogg's plant receives peanut butter and peanut paste from a Georgia plant, owned by Peanut Corp. of America, to which the
U.S. Food and Drug Administration has traced the contamination. The state is looking at 37 shipments of 47,000 pounds of peanut butter that
the plant received since August. A number of tests conducted earlier this month have come back negative. Preliminary results from the final
round of tests should be available by Friday, Reardon said.
"We will have answers in the next 24 to 48 hours, and we're very interested," Reardon said. "We'll contact the FDA and CDC and share that
information."
Within the past week, a number of food companies such as Kellogg's and retailers such as Harris Teeter and Kroger have pulled products with
peanut butter off the shelves as a precautionary measure. The FDA said Wednesday afternoon the list of products recalled is now more than
125. Kellogg Co. produces Keebler, Austin and Famous Amos brand snack crackers containing peanut butter. It confirmed Monday that
salmonella had been found in a pack of Austin Quality Foods Toasty Crackers with Peanut Butter, but did not say which factory made that
package. Other affected brand names include select products from Clif Bar, Luna, Nutrisystem and ZonePerfect. More products are being
added on a daily basis.
The investigation into the scare started earlier this month after lab tests found salmonella in an open 5-pound container of peanut butter from a
Minnesota nursing home. Testing that the state's Public Health Laboratory completed on Jan. 12 showed a genetic match with the bacterial
strain tied to 30 illnesses in Minnesota and others across the country. The CDC has said the bacteria behind the outbreak is common and not
an unusually dangerous strain, but that the elderly or those with weakened immune systems are more at risk. At least five of the six people who
died were elderly. All had salmonella when they died, though their causes of death haven't been determined.
Symptoms of salmonella infection usually begin within three days of exposure to the bacteria and generally last less than a week. In the North
Carolina cases, according to the state Department of Health and Human Services, lab results were received after most of the patients had
recovered.
Copyright 2009 by WRAL.com and the Associated Press.
Simmons 6
Multistate Outbreak of Salmonella Infections Associated with
Peanut Butter and Peanut Butter - Containing Products
• As of January 28, 2009, 529 persons from 43 states (one
person from Canada) had been reported infected with the
outbreak strain
– infection might have contributed to eight deaths
• Salmonella serotype Typhimurium shared the same pulsedfield gel electrophoresis (PFGE) pattern in PulseNet
• King Nut creamy peanut butter
– Peanut Corporation of America (PCA)
– single facility in Blakely, Georgia
– Only large lots/“tubs” of peanut butter affected
• NC connection – processing plant here made crackers
(Austin brand)
• Identified major oversight for peanut butter transport in
container trucks
Simmons 7
Senate HELP Moves Food Safety Bill
Wednesday, Nov. 18, 2009
Spurred by outbreaks of food-borne illnesses in everything from spinach to peanut butter, the Senate
Health, Education, Labor and Pensions Committee today approved a bill beefing up the FDA's ability
to oversee the nation's food supply.
The bill was approved on a voice vote. Passage came after several committee members introduced a
number of amendments on a food tracing system, nutrition claims made about baby formula, and food
labeling. The proposals were withdrawn in an effort to speed passage.
"This mark is a forward-looking bill that comprehensively reforms our current food safety system yet
is adaptable enough to keep pace with an evolving industry," said Senate HELP Chairman Tom Harkin.
"It recognizes that preventive controls are an essential means to improve food safety, and it addresses
the need to enhance surveillance, improve emergency response coordination, and heighten the
scrutiny of imported foods.“
The bill's price tag was set at $825 million for FY10, and "such sums as necessary" for the following
five fiscal years. It mirrors a companion bill introduced in the House by veteran Rep. John Dingell, DMich., which passed earlier this year by a wide margin. Passage is expected in the full Senate as well.
The bill gives the FDA expanded access to food facilities if the Agriculture secretary believes a food or
related food is tainted. It expands registration requirements of food facilities and gives the FDA the
authority to set commodity-specific standards for the safety of fresh produce. And it
directs the FDA to establish offices in at least five countries to improve the agency's overseas
presence. Harkin said food contaminations account for 325,000 hospitalizations and 5,000 deaths
annually in the United States. "These numbers are staggering and intolerable, and they are for us a
call to action," he said.
by Elaine S. Povich
Simmons 8
Food Safety in NC
1. President Obama has this as a priority
2. Steve Troxler, NC Commissioner of
Agriculture, has this as a priority
–
Commissioner’s Food Safety Forum (5 yrs)
3. NC Food Safety Task Force (mandated
by Governor Purdue)
4. NC Fresh Produce Safety Task Force
–
NCSU Kannapolis, NC campus
Simmons 9
Major Issues in NC
1.
Traceability and microbial contamination
2.
Economic impacts from outbreak or even recall
3.
NC has smaller, diverse niche markets that are
not duplicated in other states
4.
Many “small farms” – how to compete with
large farms in CA and AZ
5.
No “East Coast” concerted effort similar to the
“West Coast”
Simmons 10
Foodborne Disease Burden in The
United States
• Estimated morbidity and mortality:
– 76 million illnesses / yr
– 325,000 hospitalizations / yr
– 5,000 deaths / yr
• Estimated costs:
– billions $
– loss of consumer confidence
– loss of profits
Mead et al. (1999) Food-Related Illness and Death in the United States.
Emerging Infectious Diseases 5(5):607-625.
www.cdc.gov/ncidod/EID/index.htm
Simmons 11
Number Of Reported Foodborne Disease Outbreaks,
Cases, And Deaths, By Etiology, United States (Incl.
Guam, Puerto Rico, U.S. Virgin Islands) 1993-1997
Confirmed
etiology
32%
n = 878
Unknown
etiology
68%
n = 1873
OUTBREAKS
n = 2,751
Confirmed
etiology
59%
n = 50, 788
Unknown
etiology
41%
n = 35,270
CASES
n = 86,058
=> 29 deaths: 28 confirmed, 1 unknown etiology
Source: Surveillance for Foodborne Disease Outbreaks - United States, 1993-1997
MMWR (2000) 49(SS01):1-51
www.cdc.gov/mmwr
Simmons 12
Only a Fraction of Foodborne Illnesses Are
Routinely Reported to the CDC
1. Passive surveillance system
2. Many diseases not reportable
3. A complex chain of events must occur to report
a foodborne infection to the CDC
4. Most household foodborne infections are not
recognized or reported
Simmons 13
Foodborne Disease: Vehicles
•Fruits and
vegetables
and Other
salad
accounted for
highest
number of
outbreaks
•Beef, chicken,
and fish also
important
Most
Foodborne
Disease of
Unknown
Etiology
Simmons 14
Foods Implicated in Foodborne Illness: Meats
Red Meats
– High contamination in comminuted and
processed meats (e.g. ground beef, sausage)
• High surface area, increased contact with
processing equipment; increased handling;
variety of sources (organs, trimmings, etc.).
• E. coli O157:H7 common etiologic agent in outbreaks
assoc. with improperly cooked hamburger and other
foods
Simmons 15
Foods Implicated in Foodborne Illness: Meats
Poultry
– High contamination levels in cut-up poultry
• Increased handling, processing and contact with common equipment
• Salmonella and Campylobacter are prevalent in poultry flocks
– can contaminate an entire processing plant via equipment and process
baths (e.g., chiller tank)
– Eggs
• Endogenous contamination by Salmonella enteritidis in some flocks
– Time and temperature abuse leads to proliferation in the egg
– Raw / undercooked eggs a source of exposure and infection
Simmons 16
Foods Implicated in Foodborne Illness: Fish
Contamination depends on type of seafood, quality of harvest
water, and amount of processing, handling and storage
Bivalve mollusks (oysters, clams, mussels, etc.); filter feeders
–
Accumulate enteric pathogens from fecally contaminated waters
Crustaceans (e.g. crabs, shrimp)
–
–
Acquire some pathogens by feeding on mollusks
Acquire high levels of vibrios from their water environment
Fin fish
–
–
Outer surface and epithelial lining (e.g. gut) contamination by
enteric microbes in fecally contaminated waters;
Contamination during processing (e.g., filleting).
Simmons 17
Other Foods Implicated in Foodborne Illness
Produce (fruits and vegetables)
– fecal contamination in irrigation water and other fecal sources
(animal droppings, birds, etc.)
– inadequate or unsanitary harvesting, washing or processing.
Dairy Products
– In developed countries milk and related dairy products are usually
made from pasteurized milk.
• Raw milk and products (e.g., cheeses) made from unpasteurized
milk are high risk of bacteria contamination
– Salmonella, Campylobacter, Brucella, Yersinia, Listeria
Simmons 18
Other Foods Implicated in Foodborne Illness
• Unpasteurized fruit juices and other beverages
– fecal contamination from animal and human sources
• Deli, "Fast" and Restaurant Foods
– salads, sandwiches, other fast, deli or restaurant foods
– become fecally contaminated during preparation and handling
• Cereal and Grain: inadequate storage of cooked rice/grain
Simmons 19
Comparison Of # Outbreaks, # Cases, and
# Deaths by Food Vehicle (All Etiologic Agents):
Shellfish, Poultry, And Produce
1988-1997
Shellfish
OUTBREAKS
81
CASES
2,547
DEATHS
3
Poultry
70
2,707
0
Produce
130
14,805
11
MMWR (1996) 45(SS-5):1-66;
MMWR (2000) 49(SS-01):1-51
Simmons 20
Foodborne
Disease:
Etiologic Agents
Most reported
outbreaks and
cases are caused
by bacteria:
•Salmonella
•Campylobacter
•E. coli
•Cl. perfringens
•Shigella
•Staph. aureus
These pathogens were
responsible for 22% reported
outbreaks; 49% cases; 79%
deaths from 1993-1997
Simmons 21
Food Poisoning vs. Food Infection
Food poisoning or food intoxication: disease that
results from the ingestion of food containing
microbial toxins
– Microbes that produced the toxins do not have to grow
and are often not viable at the time the food is
consumed
Food infection: active infections resulting from
ingestion of pathogen-contaminated foods
– Microbes are actively growing in the host
– Clinical illness associated with microbial infection, but
may also be attributed to toxins produced by the
actively growing microbes
Simmons 22
Salmonella
• Causes an estimated 1.4 million
foodborne illnesses / year
• Est. 500 deaths / year
• Decrease risks for egg-associated infections of S. enteritidis
by not eating raw or undercooked eggs
• ~40% of persons who died from S. enteritidis were residents of
nursing homes; serious disease in others with weakened
immune systems
– Nursing homes, hospitals, and commercial kitchens should use
pasteurized egg products for all recipes requiring pooled or lightly
cooked eggs.
• Proper egg storage in homes.
Simmons 23
Campylobacter jejuni
• Causes an estimated 2.5 million
foodborne illnesses / year
• Among the most common causes of
enteric infection in humans overall
• Usually mild disease in immunocompetent hosts
• for immunocompromised hosts, antimicrobial therapy needed
• ~2 in 100,000 diagnosed infections lead to Guillan-Barre
syndrome, a paralysis that lasts several weeks
• Primary vehicles: milk, poultry, pork
• colonization of poultry flocks almost universal; 106-107 cells /
processed bird
• inadequate cooking, cross-contamination primary causes of infection
Simmons 24
Escherichia coli
E. coli 0157:H7 (EHEC)
• Causes at least 60,000 infections
and 50 deaths per year
• Leading cause of kidney failure in children
• Produces a verotoxin (enterotoxin) similar to Shiga toxin
• Associated with undercooked meat, particularly ground meat
E. coli (ETEC)
• “travelers diarrhea”
• Produces two heat-liable
enterotoxins
• Associated with fresh vegetables
Also, enteropathogenic (EPEC) and
enterinvasive (EIEC) E. coli
Simmons 25
Clostridium
Anaerobic spore-forming, gram-positive rod;
ubiquitous in the environment
Clostridium perfringens
• Most prevalent cause of food poisoning in
the US (248,000 cases per year)
• Perfringens enterotoxin
• Generally self-limiting
Clostridium botulinum
• Botulism – severe food poisoning
• Neurotoxin – seven distinct types of botulinum toxin
• Destroyed by high heat (80oC, 10 m)
• Associated with foods not cooked after processing; homecanned vegetables, smoked fish vacuum-packed
Simmons 26
FOODNET:
1. Active lab-based surveillance
2. Survey of clinical labs
3. Survey of physicians
4. Survey of the population
5. Epidemiologic studies
FoodNet also looks for:
Listeria monocytogenes
Vibrio spp.
Yersinia enterocolitica
Cyclospora
Cryptosporidium
www.cdc.gov/foodnet
Simmons 27
HOWEVER, Recall that 68% of Reported
FBDOs were of Unknown Etiology
•Retrospective analysis of clinical data shows that about
50% had incubations period of >15 hours, suggesting viral
etiology. Viruses (e.g., Noroviruses; human caliciviruses)
are likely a much more important cause of foodborne
disease outbreaks than is currently recognized.
•Local and state public health programs lack resources and
expertise to diagnose viral pathogens, but methods are
becoming increasingly available.
Viral outbreaks are more likely to be
detected in the future.
Simmons 28
Human Caliciviruses
•
ex. Norwalk-like virus(es)
•
Major agents of foodborne disease.
•
Outbreaks due to fecally contaminated bivalve
mollusks, deli meats, produce, and many other foods.
•
Relatively persistent in the environment.
•
Fecal-oral transmission in all age groups; worldwide; direct / indirect
contact; secondary spread: common, 25-50%.
•
Causes acute gastroenteritis: humans are only host;
~1-2 day incubation period and ~1-4 day duration;
(diarrhea, vomiting, nausea, abdominal pain, anorexia, etc.)
•
Multiplies in upper small intestine epithelium; blunts microvilli
Simmons 29
Hepatitis A Virus (HAV)
•
•
•
•
•
•
•
•
Fecal-oral route of exposure
Incubation period: 2-6 weeks
Serious debilitating disease (general infection): fever, abdominal pain,
headache, jaundice, nausea, diarrhea
Fecally excreted at concentrations up to 106 infectious units per gram (>109
virions per gram)
Infectious at relatively low doses
Persistent in feces and on foods and environmental surfaces for weeks to
months, depending on temperature and other environmental factors.
Heat resistant: requires >60oC for rapid inactivation.
HAV associated with largest documented outbreak of shellfish illness ever
recorded:
– ~300,000 cases in Shanghai, China 1988
– Traced to consumption of clams harvested from a sewage-polluted area.
Simmons 30
Natural Toxins
Toxin: A poison, usually a protein, formed by microorganisms.
• Exotoxins are given off as waste products of a microorganism.
• Endotoxins are contained within the cells, and are liberated only
when the cell dies and disintegrates.
Marine Biotoxins
•
Ciguatera poisoning (fish)
•
Shellfish toxins (PSP, DSP, NSP, ASP)
PSP=paralytic; DSP=diarrheal; NSP=neurotoxic,
ASP=amnesic shellfish poisoning
•
•
Scombroid poisoning (fish)
Tetrodotoxin (Pufferfish)
Fungal And Plant Toxins
•
Mushroom toxins
•
Aflatoxins
•
Pyrrolizidine alkaloids
•
Phytohaemagglutinin (Red kidney bean poisoning)
•
Grayanotoxin (Honey intoxication)
Simmons 31
Sources of Foodborne Enteric Microbial Contamination
Food handler-associated contamination: inadequate personal hygiene 
fecal contamination of foods (e.g., hands)
Food processing: equipment, packaging, and personnel may contaminate
foods during processing
Simmons 32
Sources of Foodborne Enteric Microbial Contamination
Food storage: time and temperature abuse  bacterial growth
Fecal contamination prior to harvest or collection:
– Animal foods contaminated naturally (e.g., salmonella)
– Surface contamination (e.g., feces on fur, feathers,
hooves, etc.)
– Shellfish and finfish contaminated in their environment
• Fecal (sewage) contamination of water  pathogen uptake
by filter-feeding on waterborne particles
– Fish and shellfish naturally colonized by aquatic
pathogens (e.g. Vibrios)
– Produce contaminated by irrigation with sewage or
contaminated water or fertilization with nightsoil (feces)
or animal feces.
Simmons 33
Factors Contributing to the Emergence
of Foodborne Diseases
•Human demographics
-growing segments of the population at
increased susceptibility to infections; ex. elderly
•Human behavior
-changes in dietary patterns; ex. increasing consumption
of produce, fish, shellfish
•Changes in agricultural industry and technology
-greater geographic distribution of certain types of foods
-mass production, rapid dissemination
•Microbial adaptation / evolution
-environmental conditions; antimicrobial resistance
-newly emerging human pathogens
•Public health infrastructure
-limited or passive surveillance; monitoring; lack of $$
Simmons 34
Microbial Contamination of Foods
Food spoilage: any change in the appearance, smell,
or taste of a food product that makes it
unacceptable to the consumer
–
May or may not make the food unsafe to eat
Foods can be classified into categories with respect to
spoilage:
1)
2)
3)
Perishable foods
Semiperishable foods
Stable or nonperishable foods
related to their moisture content or water activity
Simmons 35
Methods to Control Microbial
Contamination of Foods
1.
2.
Prevention: keep enteric microbes out
Remove enteric microbes
–
–
–
3.
Identify and remove contaminated food items and ingredients
Wash to remove contaminants filtration or
other physical separation methods
Depurate or relay live shellfish.
Inactivate: kill / destroy microbes
–
–
–
–
4.
Use of heat
•
sterilize
•
disinfect (e.g., pasteurize and cook to destroy pathogens)
Drying, dehydration and intermediate-moisture processing
Chemical treatments: disinfect and sanitize
Irradiation: UV and gamma (ionizing) radiation
Prevent growth of microbes
–
Use cold and freezing to prevent proliferation
Simmons 36
Methods to Control Microbial
Contamination of Foods
Prevent exposure to fecal contamination in the environment,
after harvest or during processing, preparation and handling:
Maintain uninfected herds and flocks of animals
1. Immunize animals against infectious diseases:
•
Brucella abortus: brucellosis from cattle;
raw milk/dairy products
2. Colonize animals with harmless microflora:
•
colonize baby chicks with harmless
bacteria competitive to Salmonella
3. Destroy animals harboring pathogens:
•
Bovine Spongiform Encephalopathy (BSE; “mad cow” disease)
– caused by a prion able to infect humans (neural tissue in meat)
Maintain sanitation in the environment
1. harvest shellfish only from waters that are not fecally contaminated
2. irrigate fruits and vegetables with non-fecally contaminated water
3. use uncontaminated fertilizer for fruits and vegetables
Simmons 37
Methods to Control Microbial
Contamination of Foods
Maintain adequate hygiene and sanitation during harvest,
processing, storage and distribution
1. Use clean water for washing, processing,
cleaning and worker hygiene
2. Adequate human and food waste treatment and disposal facilities
3. Plant and equipment sanitation: clean, sanitize, etc.
4. Personal hygiene, food handling practices and
employee health (education, training and policies)
Source control: use of non-fecally contaminated foods and ingredients
1.
2.
Establish criteria, standards, and guidelines for measuring fecal
contamination of foods (pathogens and microbial indicators)
Inspection, monitoring and surveillance (product testing)
Simmons 38
Heat and Thermal Treatment
Effects of heat vary with food composition and microbe
• food composition: water, fat, proteins, carbohydrates, salts and pH
• organism factors: form, composition, growth stage, age, etc.
Sterilize (or nearly sterilize) foods (destroys all viable microbes)
– heat >100oC; usually uses high pressure and steam
– typical target temperature is 115-116oC for about 60 minutes
• ex. retorting of canned foods
Pasteurization
– intended to kill pathogens but does not sterilize the food
– often used prior to subsequent cold storage so pathogens
or spoilage organisms do not proliferate
• High Temperature-Short Time Method: 72oC; 15 sec. (milk)
• Low Temperature-Long Time Method: 62.8oC for 30 min. (milk)
– pasteurization times and temperatures for other foods depend on the
effects of heat on the food, food composition and the target organisms of
interest
Simmons 39
Drying, Dehydration, and Desiccation
Low moisture foods: usually <15% moisture
Intermediate moisture foods (IMF): 15-50% moisture
– fruits, cakes, syrups, candies, jams, milks,
some meats and cheeses
•
•
•
•
Sun (natural) drying: often used for fruits
Heat drying (dehydration; desiccation)
Freeze drying (lyophilization; cryophilization)
Condensing or evaporating: reducing moisture in
a liquid food; e.g., evaporated or sweetened condensed milk.
Drying destroys some enteric microbes but
is not very effective for others
Simmons 40
Chemical Treatments
Preservatives:
– Most are designed to control certain bacteria and molds
• Generally, ineffective against viruses and protozoan cysts
– Propionates, sorbates, benzoates and p-hydroxybenzoates: molds
– Nitrates and nitrites (ex. for Clostridium botulinum; Cl. perfringens)
– Sulfur dioxide and sulfites
– Acetic, lactic and other organic acids
– NaCl and sugars
– Ethylene and propylene oxides
Disinfectants and sanitizers:
– Used to treat (by washing or dipping) certain meats and produce
– Chlorine, peroxyacetic acid, ozone, hydrogen peroxide
– Concentrations: 10s to 100s of mg/L; contact times: seconds to minutes
– Organic acids (acetic, lactic and citric) at 2-7%; less effective
Simmons 41
Food Irradiation
Ionizing radiation (X-rays and gamma rays)
– Becoming more widely used
• gamma radiation from Co-60 and Cs-137 sources
– Effectiveness depends on: organism, composition of the food,
temperature, and presence of oxygen
• undesirable changes in foods from excessive radiation
UV radiation
– low (monochromatic 254 nm) and medium (polychromatic)
– used primarily for beverages: water, juices, ciders, etc.
Simmons 42
Shellfish Depuration and Relaying
Place live bivalve mollusks shellfish in clean flowing seawater
– normal pumping, feeding and related activity rids accumulated microbes
Relaying:
– transfer shellfish from contaminated (restricted) waters to uncontaminated
natural estuarine waters
– typical holding times in the clean water are two weeks or longer
Depuration:
– Place restricted shellfish in shore-based tanks of clean, flowing seawater
under controlled conditions for periods of several days
– Factors influencing deputation efficiency:
• tank geometry and loading
• water quality
• temperature
Simmons 43
Hazard Analysis / Critical Control Points
(HACCP)
A program of process control to (1) identify microbial hazards,
(2) identify the most vulnerable (critical) sites or steps in the
process and (3) implement an in-house monitoring system for
quality assurance and hygiene.
Incorporates elements of:
(i) education and training
(iv) inspection
(ii) ingredient or commodity control
(iii) process control
(iv) microbiological and
related surveys
HACCP is designed and implemented on a commodity-specific
and production facility-specific basis
Simmons 44
Foodborne Safety in the Home
• Investigations from outbreaks indicate that consumers do not
always take precautions to reduce the risks of foodborne
infections
• About half of all Salmonella cases result from unsafe handling of
food in the home
• Many experts believe the kitchen harbors more potentially
dangerous bacteria than even the bathroom
• Individuals at increased risk and others in the population may be
unaware of the risks involved, or of risk-reducing practice(s)
Simmons 45
Steps to Prevent Foodborne Illness
1.
Clean: wash hands
and surfaces often
2.
Separate: don't
cross-contaminate
3.
Cook: cook to
proper temperatures
(minimum 160oF)
4.
Cool / chill:
refrigerate promptly
(refrigerator= 41oF)
Simmons 46
Questions and Comments
Have a Great Thanksgiving!!
Simmons 47