Lecture 18 Foodborne Disease

8/7/2019 Lecture 18 Foodborne Disease

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Control of Foodborne Disease



Today

� Review of classes of food-borne disease,

types of contamination, sources and

factors affecting growth� HACCP

� Types of controls

± Physical Methods ± Chemical Methods

± Biological Methods



Classes of Food-borne Disease

� Infection ± Foodhandler

± Food Concentration

± Direct Contamination

± Water-washed

� Toxico-infection

� Intoxication (food poisoning)

± Bacterial and Fungal Toxins ± Shellfish Toxins

± Metals, Chemicals, etc.

� Allergy



Types of Contamination

� Viral

� Bacterial

± Cells ± Products

� Fungi

± Products� Protozoa and Helminths

� Other (Cyanobacteria??)





Microbial Growth in Food

� Bacteria and Fungi

� Complex Ecology

± Interaction with multiple environmental factorscontrols whether an organism can grow in a

given environment

� Food Preservation

± Ecology of zero growth





Microbial Growth in Food

� Intrinsic Factors:

± pH

± Water Activity

± Salt Concentration

± Nutrients

± Etc.

� Extrinsic Factors

± Temperature

± Gaseous Conditions

± Presence of Other

Microbes

Heterogeneity

- Question of scale

- Food items may have several distinct

microenvironments



HACCP

� Hazard Analysis and Critical Control Point ± Framework to identify risks and control hazards

� Preliminary steps ± Gain management support

± Assemble HACCP team

± Describe the food and method of distribution

± Identify the intended use and consumers

± Develop a flow diagram

± Verify the flow diagram

� Establish plan-specific objectives and performancecriteria



7 Principles of HACCP

1) Conduct a Hazard Analysis

a. Hazard identification

b. Hazard evaluation

c. Identification of control measures

d. Determine influence of prerequisiteprograms

2) Determine the Critical Control Pointsa. Consideration for product type

b. Use of decision trees




3) Establish Critical Limits

a. Defined as ³ a maximum or minimum value

to which a biological, chemical, or physical

parameter must be controlled at the CCP to

prevent, eliminate, or reduce to an

acceptable level the occurrence of a

significant food safety hazard

b. Typically process based rather than

microbiological




4) Establish Monitoring Procedures

a. What is being monitored

b. How often

c. Procedures to collect data

d. Responsibility

5) Establish Corrective Actions

a. Fix or correct problemb. Determine disposition of product

c. Re-evaluate HACCP plan




6) Establish Verification Process

a. Methods, procedures, and/or tests used toverify compliance to HACCP plan in addition

to monitoringb. Essentially QA/QC

7) Establish Record-Keeping andDocumentation Procedures

a. HACCP Plan and supporting documentation

b. Records obtained during operation of plan



Control of Food-borne Microbes

� Poor- No control over food production,

distribution, or consumption

� Good- Prevent degradation of product bycontrol of shelf-life and environmental

factors

� Better- Chemical, Physical or Biological

Treatment

� BEST- PREVENT CONT AMINATION



Physical Controls

� Water Activity

± Dehydration

� Drying- air

� Freeze-Drying (vacuum sublimation of ice content)

± Minimal aw needed for growth

� Bacteria 0.91-0.88

� Yeasts 0.88

� Molds 0.80

� Halophilic bacteria 0.75

� Xerotolerant molds 0.71

� Xerotphilic molds and osmophilic yeasts 0.62-0.60



Physical Controls

� Temperature Controls ± Cool Storage (4-12ºC)

� Controlled-Atmosphere Storage

� MAP/VP

± Freezing and Frozen Storage (-15 to -40ºC)

± Heat Treatments� Autoclaving

� Dry Heat Sterilization

� Pasteurization/Flash Pasteurization� Tyndalization

� Microwave heating

� Ohmic Heating



Physical controls

� Ultrasound ± Synergy with heat

� Irradiation

± UV Radiation ± High-Intensity Pulsed Light� Xenon lamps

± Ionizing Radiation� Gamma

� E-Beam

� Hydrostatic Pressure

� Electric Field Effects

� Magnetic Field Effects



Chemical Controls

� Organic Acids and Esters ± E.g. acetic, lactic, propionic, sorbic, benzoic

± Related to pH (used in foods with pH<5.5)

� Dimethyl Dicarbonate ± Highly reactive with wide range of compounds

± Primarily targeted at yeasts, but also bacteriocidal

± Inactivates enzymes

� Lysozyme

± Targets peptidoglygan causing hydrolysis ± Egg albumin

± Increased effectiveness with pretreatment chelators



Chemical Controls

� Nitrites

± Particularly good against C. botulinum

± Inactivates enzymes; better under anaerobic

conditions, and low pH

� Parabens

± Antimicrobial activity related to length of chain

± Better against molds and yeast than bacteria; but more

effective against Gram + than Gram ±

± Inhibit nutrient uptake (e.g. amino acids line serine)



Chemical Controls

� Phenolic Antioxidants

± E.g. BHA, BHT, propyl gallate, and TBHQ

± Function: Delays auto-oxidation of unsaturated lipids

� Interupts free-radical chain mechanism of

hydroperoxide formation

± Similar antimicrobial mechanism to Parabensand other phenolics; higher levels required



Chemical Controls

� Phosphates

± E.g. sodium acid pyrophosphate (SAPP),

TSPP, STPP, SHMP, TSP

± Gram + more susceptible than Gram ±

± Mechanism: metal chelation

� Inhibits cell division

± Interference with Mg2+

-dependent enzyme.

� Salt (NaCl)

± Water activity



Chemical Controls

� Sulfites and Sulfur salts

± Targets spoilage and fermentative yeasts,

molds, acetic acid bacteria, and malolactic

bacteria

± Act as antioxidants; inhibit enzymatic activities



Natural Chemical Compounds

� Lactoperoxidase System

± Enzyme in milk

± Better against Gram ±

� Lactoferrin and Other Iron BindingProteins

� Avidin (glycoprotein in egg albumin)

± Binds biotin (a co-factor for enzymes)� Spices and Oils

� Phenolics



Biological Controls

� Controlled Acidification

± E.g. lactobacilli and lactococcal bacteria

� Bacteriocins ± E.g. Nisin (temp-dependent)

Documents

Lecture 18 Foodborne Disease