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BIO 425
Industrial MicrobiologyLecture 9
Other pathogenic microorganismsNovel techniques to eliminate m/os
HACCP
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Content outline Shigella spp. Listeria spp.
Yersinia spp. Clostridum spp. Brucella spp. Mycotoxins
Techniques to eliminate microorganisms HACCP concept
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Shigella spp. Differs from theE.coliby the lack of gas
production,
important genera; Shigella dysenteriae causes diarrhea, mild or severe, be watery or bloody. Symptoms are:
fever and nausea, vomiting, abdominal cramps.
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Listeria monocytogenes
Gr (+), non-spore former,
less sensitive to heat
can grow at T, as low as 3o C
Present in both raw and processed food(mainly milk & cheese, seafood meat
products, raw vegetables)
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Listeria monocytogenes
Responsible for opportunistic infections,
mainly in pregnant women,
newborns and elderly.
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Main symptoms of Listeriosis:
meningitis,
encephalitis or septicaemia
can lead to abortion, or premature birthwhen pregnant women are infected in thesecond and third trimesters.
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Yersinia enterocolitica
Three pathogenic species of genus Yersiniais repeated.
Cause gastroenteritis, rod shaped.
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Yersinia pestis
the causative agent of the plague.
Genetically very similar to Y.pseudotuberculosis.
but infects humans by routes other thanfood.
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Y. enterocolitica
detected in environmental and food sourcessuch as
ponds,
lakes,
meat, ice-cream and milk.
Most isolates are reported to be notpathogenic.
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Staphylococcus aureus
Gr (+), cocci;
pathogenicity & food poisoning is throughenterotoxins.
(different types (7) varied by antigens, resistant tocooking and proteolytic enzymes), highly heat-stable toxins.
Exist in air, dust, sewage, water, milk & food,present in nasal passages and throat.
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Foodstuff frequently invaded by S.
aureus
meat & meat products, poultry & egg products,
salads such as egg, tuna, chicken, potato andmacaroni,
cream-filled pastries, cream pies, sandwichfillings,
milk & dairy products.
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S. aureuspoisoning is observed in:
foods that require considerable handling
during preparation. and that are kept at slightly elevated
temperatures after preparation:
frequently involved in staphylococcal foodpoisoning.
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Onset of symptoms include forS.
aureus
1. Nausea, 2. Vomiting,
3. Abdominal cramps.
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Clostridium perfringens
Anaerobic,
G (+),
Spore-former rod,
Spores persists in soil, sediments.
Areas subject to human or animal faecalposition.
Meat & meat products & gravy cheese arethe foods most frequently implicated.
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Clostridium perfringens
Five types (A-E) ofClostridium perfringensaccording to exotoxins.
Common symptoms include abdominal pain, Nausea,
acute diarrhea.
They start after 8-12 hours of consumption of thetoxin producing Clostridium perfringens.
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Clostridium perfringens
Small no. of the organisms are oftenpresent as spores after cooking.
The spores generate;
and the Clostridia multiply to food
poisoning levels;during the cooking period and storage.
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Clostridium perfringens
The cooking process drives off oxygen,
hence creating an anaerobic environment
favorable to Clostridialgrowth. After ingestion:
the enterotoxin is produced in the intestine,
associated with sporulation,possibly induced by the acidic environment
of the stomach.
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Clinically important Clostridium
spp.
C. botulinum
C. perfringens
C.difficile
C.tetani
C.botulinum and C.perfringens--> foodpoisoning
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Botulism through neurotoxins.
They block the release of theneurotransmitter acetylcholine (AcH)
results in muscle weakness & subsequentparalysis.
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Botulism Associated with canned food,
(esp. Home canned) low acid foods,
vegetables, meat and fish products. Also associated with honey;
and hence honey should not be given to
children under one year old: Infant botulism is milder than the adult
version.
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Bacillus cereus
Sporeformer,
G(+), facultatively aerobic;
survive during cooking process.
They grow well in cooked food because ofthe lack of a competing microflora.
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Brucella
Brucella melitensis (goats) Brucella abortus (cattle)
Brucella suis (swine)
strictly aerobic and Gr (-) coccobacilli->cause Brucellosis,
enters via skin, respiratory tract or the
digestive tract.
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Brucella
The intracellular organism can enter the blood andthe lymphatics;
where it multiplies inside phagocytes andeventually cause bacto-aemia (bacterial defectionof blood);
Includes high fever, chills and sweating;
Pathogenicity:related to the production of lipopolysaccharideslike poly N-formyl peroxamine O chain.
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Mycotoxins
Produced by fungal genera;
Aspergillus,
Fusarium
Penicillium.
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Aflatoxins
Produced by Aspergillus spp.
(B1,B2,G1,G2) by the blue or green fluorescence
given under an UV lamp.),B1 is most toxic.
Symptoms: acute necrosis,
cirrhosis & carcinoma of liver, Potent carcinogen in birds, rodents, fish & human.
Liver: the primary target of organism.
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Methods of preservation and shelf life
extension of food:
Pasteurization: applied to milk & some of fermentedfoods or juices. 630 C for 30 min. In milk HTST; high temp. short time, by 720 C for 15
sec.
Designated to kill all pathogenic bacteria; e.g.Mycobacterium tuberculosis, Salmonella spp., Brucellaspp.
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More on pasteurizationThermoduric organisms survive
pasteurization;
including; Streptococcus thermophilus
Enterococcus faecalis
Bacillus cereus -> its growth causepasteurized milk spoilage known as bittycream.
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Sterilization Milk sterilization (130o C at least 1 second.):
a well established method for prolonged milkstorage (UHT).
(140o
C for milisecond). The heat treatment:
severe enough to kill all m/o present.
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Sterilization By heating:
Both spoilage and foodborne pathogens:
to an acceptable level. There is a statistical chance of anorganism surviving the process,
but this is acceptable: in the normal sense of safe food
production.
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High hydrostatic pressure (HHP) High hydrostatic pressures of 300 to 500
MPa are applied: inactivate vegetative bacteria,
whereas higher pressures (
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F
ood irradiation:Exposure of food, either packaged or in bulk
to controlled amounts of ionization
radiation (usually gamma rays from 60Co); for a specific period of time to achieve
certain desirable objectives.
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F
ood irradiation: Presents the growth of m/o by damaging the
DNA.
It can also delay ripening and maturation bycausing biochemical reactions in the planttissues.
limited to radiation from high energy -rays, X-rays and accelerated electronse.g. Microwave technology
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R
educed oxygen packaging (R
OP):
Its results in the food being surrounded by anatmosphere are observed:
which contains little or no oxygen.
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Controlled atmosphere packaging
(CAP):
an active system in which a desired
atmosphere is maintained for the duration: of the shelf life by the use of agents to bind;
or scavenge oxygen or a gas generating kit.
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Modified atmosphere
packaging(MAP): uses a gas flushing and sealing process;
or reduction of oxygen through respirationof vegetables or microbial action.
defined as packaging of a product in anatmosphere;
which has had a one-time modification ofgaseous composition;
so that it is different from that air.
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Modified atmosphere packaging
(MAP)defined as the enclosing of food products in
an atmosphere inside gas-barrier materials,
in which the gaseous environment has beenmodified to slow down;
respiration rate,
microbial growth; and reduce enzymatic degradation, with
shelf life extension.
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Modified atmosphere
packaging(MAP) Solid CO2 (dry ice) controls m/o growth by
acting as:
a refrigerant during transport and storage.
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Vacuum packaging:
If the amount of air is reduced from a
package; and hermetically seals it;
so that a near-perfect vacuum remains
inside.
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Ultrasound: Waves inactivate m/o by introducing
alternating compression;
and expansion cycles in a liquid medium.
Small bubbles grow during the expansion ofultrasound.
Temperature & pressure reached inside thebubbles is extremely high.
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HACCP:Hazard Analysis Critical Control
Point
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HACCP Implementation
late 1960s;
the National Aeronautics and SpaceAdministration (NASA) & U.S Army laboratories
jointly developed the HACCP concept.
then introduced to food industry.
a simple but very specific way to find hazards in
a food product. designed to prevent, rather than detect food
hazards.
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HACCPlooks at the flow of food through the
process:
provides a way to determine which pointsare critical for the control of foodbornedisease hazards;
and monitors each operation frequently.
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HACCP combines two criteria:
1. A hazard is something that could harm the
consumer.2. A critical control point(CCP) is an operationor step where something can be done to
prevent or control a hazard.
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HACCP concept has two parts;
(HACCP principles)
1. Hazard analysis depends on anunderstanding of which chemical and
physical contaminants and m/o can bepresent and the factors that affect their
growth and survival.
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HACCP concept has two parts;
(HACCP principles)2. Critical control points are the points:
where controls are needed to make sure thatmicrobes do not reach the food, survive orgrow to dangerous levels.
Not all steps in a food production process
are critical; and it is important to separatecritical and non-critical points.
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HACCP concept has two parts;
(HACCP principles)A flow diagram developed during hazard
analysis can help to find CCP.
Monitoring may take the form ofobservation, physical measurements (e.g.temperature, pH) or microbial analysis.
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Factors most often affect foodsafety & acceptability
1.Contaminated raw food or ingredients.
2.Poor temperature control during processing andstorage (time-temperature abuse).
3.Improper cooling(failure to control to
refrigerated temperature within 2 hrs.).4.Improper handling after processing.
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Factors most often affect food safety
& acceptability:5.Cross-contamination.
6.Poor cleaning of the equipment.
7.Failure to separate raw and cooked products.
8.Poor employee hygiene and sanitation.
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For HACCP to function well inthe food industry:
1. Food processors and regulators must learnabout HACCP.
2. Plant personnel must apply their technicalskills to the program.
3. Sanitarians should drop HACCP controls
points that are not hazardous from the program.
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For HACCP to function well in thefood industry
Development of HACCP in a food plantthrough good manufacturing practices
(GMPs) & sanitary standard operatingprocedures(SSOPs)
in accordance with Total Quality
Management (TQM) & implementation ofISO 9000, 9001, 9002, 14000 and 22000.
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Success with HACCP:
Employees in a food plant need special training to useHACCP.
If all employees understand the important of keeping
CCPs within the critical limits: cost effective control can replace costly crisis
management;
and outbreaks of foodborne illnesses can be reduced.
A ff i HACCP
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An effective HACCP programrequires four steps;
1.Management education:
Awareness & introduction of all staff via
quality assurance.2. Operational steps:
Team must need to change plant design and
operating system to take more hygienicmeasures.
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An effective HACCP programrequires four steps
3. Employee maturation:
Good working conditions for maturatingstaff to carry out HACCP.
4. Employee involvement:
Formation of quality circles among all
levels of employees from boss to non-qualified any workers.
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LITERATURE CITED
Forsythe, S.J. The Microbiology of Safe Food,Blackwell Science, Cambridge, 2000.
kmen, Z. A. , Food Microbiology LaboratoryBook, Food Engineering Department, Middle EastTechnical University, Ankara, 1995.
Pelczar, M. J. ; Chan, E. C. S. ,Krieg, N. R.Microbiology, Fifth edition, Mc Graw Hill Inc.
Singapore, 1986. Wood, B. J. B., Microbiology ofFermentedFoods, Vol.1 and 2, Blackie Academic andProfessional, London, Second edition, 1998.