industrial 9

8/4/2019 Industrial 9

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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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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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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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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 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 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.

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