useful microbiological testing in food safety and quality management
TRANSCRIPT
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Useful Microbiological Testing in Food Safety & Quality Management
Katherine M.J. Swanson, Ph.D.Vice President Food Safety EcolabPresident-Elect IAFP
Arkansas Association for Food ProtectionSpringdale, ARSeptember 14, 2011
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Discussion Topics
International Association for Food Protection greeting
Different tests serve different purposes
Testing for maximum value
Our mission is working
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IAFP Executive Board 2011-2012
President-Elect
Katie SwansonEcolab, Inc.
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Don SchaffnerRutgers University
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State University
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Gloria Swick-Brown
Ohio Dept. of Health (retired)
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Different Tests Serve Different Purposes
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Microbial Testing “Microbial testing” means
different things to different people Reams of data Detective game to identify unknown or
causative agent Presence/absence or qualitative
reaction that’s observed Quantitative measurement of the
microbiological status of a sample or lot
OR
Presentation focuses on process control and product acceptance
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The Purpose of a Test Determines:
The target Indicator or pathogen
The method Time to results, accuracy, repeatability, etc.
The sample Environment, line residue, end product, location collected, size/ number of samples
The frequency Daily, weekly, monthly, etc. or event triggered
The interpretation Investigational, routine, regulatory, etc.
The action Rejection, process adjustment, recall, outbreak investigation, etc.
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International Commission on Microbiological Specifications for Foods
Founded in 1962 to advance scientific concepts for government and industry consideration to: Reduce foodborne illness Facilitate global food trade Focus on testing applied to foods
Membership 6 Academia, 6 Government, 5 Industry from 11 Countries All work is voluntary and without honoraria
Partners with FAO, WHO, ILSI, IUFoST, IAFP etc.
Provides advice through books, papers, workshops, etc. Advice has no official status
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When & Where to Test for Food Safety Management
When there is good evidence that: There is a microbiological problem
- Food safety or quality
- Historical or current
AND
Testing will help to control the problem
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Target Organism Examples
EXAMPLES
Utility Spoilage, reduced shelf life, no health concern
Total counts, yeast, mold, etc.
Indicator Measure of GHP or process control Coliforms, generic E. coli, Enterobacteriaceae, etc.
Moderate hazard
Not life threatening, short duration, self limiting, no sequelae
S. aureus, B. cereus, C. perfringens, Norovirus, etc.
Serious hazard
Incapacitating, usually not life threatening
Salmonellae, Shigella flexneri, Yersinia enterocolitica, etc.
Severe hazard
Life threatening, chronic sequelae, or long duration OR
Designed for sensitive sub-population
E. coli O157:H7, C botulinum toxin or Cronobacter (infants)
ICMSF Hazard Categories
From ICMSF Book 7
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Key ICMSF Sampling Plan Terms
n Number of sample units analyzed
c Maximum number of sample units with unsatisfactory test results
m Level that separates acceptable quality from marginally acceptable or unacceptable quality
M Level above which is unsatisfactory or requires further investigation
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Choosing m and M
m M
Re
lati
ve
pro
po
rtio
n o
f s
amp
le u
nit
s in
a lo
t
Mean log count
No concern Decisive concernSome concern
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ICMSF Suggested Sampling Plans
Hazard Group
Likely Change Before Consumption
Reduce No Change Increase
Utility Case 1
n=5, c=3
Case 2
n=5, c=2
Case 3
n=5, c=1
Indicator Case 4
n=5, c=3
Case 5
n=5, c=2
Case 6
n=5, c=1
Moderate Case 7
n=5, c=2
Case 8
n=5, c=1
Case 9
n=10, c=1
Serious Case 10
n=5, c=0
Case 11
n=10, c=0
Case 12
n=20, c=0
Severe Case 13
n=15, c=0
Case 14
n=30, c=0
Case 15
n=60, c=0
FOR LOT ACCEPTANCE TESTING
Ana
lytic
al
unit
= 2
5g
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Sample Size Influence on Probability of Acceptance
0
0.2
0.4
0.6
0.8
1
1.2
0 5 10 15 20
% Defective
Pro
babi
lity
of A
ccep
tanc
e
n = 15
n = 30
n = 60
m = 0
86%
74%
55%
1%
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Testing to Maximize Value
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Useful Microbial Testing
Identification of contamination sources
Environmental monitoring to identify potential harborage sites
Utility and indicator organisms to verify effective controls & trends Effective processing Effective control of post process contamination
Investigation sampling for problem solving
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Process Example
Process 1
Process 2
Process 3
Packaging Line A
Packaging Line B
Ingredients
What action do you take when an unacceptable result is found on Line B?
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Result Format Influences Information Provided
Presence/Absence
0 10 20
Lot Number
Quantative
0
1
2
3
4
5
0 10 20
Lot Number
Lo
g (
CF
U/g
)
Positive
Negative
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0
1
2
3
4
5
0 10 20
Lot Number
Lo
g (
CF
U/g
)
Trend Analysis Can Inform Process Control
0
1
2
3
4
5
0 10 20
Lot Number
Lo
g (
CF
U/g
)
0
1
2
3
4
5
0 10 20
Lot Number
Lo
g (
CF
U/g
)
0
1
2
3
4
5
0 10 20
Lot Number
Lo
g (
CF
U/g
)
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Testing Considerations
Primary production
Ingredients
In-process
Processing environment
Shelf life
End product
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Book 8 Contents Part 1-Principles
Utility of microbial testing for safety & quality
Validation of control measures Verification of process control Verification of environmental
control Corrective action to re-establish
control Microbial testing in customer-
supplier relationships
Part 2 – Product Categories Meats Poultry Seafood Feed & pet food Vegetables Fruits Spices, dried soups, flavorings Cereals Nuts, oilseeds, dried legumes Cocoa and confectionery Oil based foods Sugar, syrups, honey Beverages Water Dairy products Eggs Shelf stable, heat treated foods Infants and young children Formulated foods
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Primary Production
Included when production conditions have a major influence on the microbial quality or safety Fruits, vegetables, spices, meat, poultry and
fish products
Examples of samples to consider Irrigation water Fertilizer Feed Other on-farm practices
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Ingredient Testing
May be useful for some applications and not others
Example - cocoa powder:Used in chocolate, no heat treatment? Used in ice cream mix that is
subsequently pasteurized
Question Is control at the ingredient step
necessary?
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In-Process Testing
Verify a kill step or predict potential re-contamination
Examples Intermediate product, line residues, tailings,
wash water Typically indicators with quantitative results
Questions: Is the process needed to control a microbial
concern? Is testing needed to verify:
- the process is functioning as intended or- contamination is not occurring in the process?
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Processing Environment Testing
Use to verify that the environment is under appropriate hygienic control
Examples Swabs or sponges for equipment or in the
environment Rapid testing to verify cleaning & sanitation
adequacy
Identify harborage sites that can contaminate end product
Frequently, earlier detection of issues than end product testing
Questions considered: Does the environment need to be controlled
to prevent contamination? Will testing be beneficial to verify control?
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Shelf Life Testing
Relevant for products subject to microbial spoilage
Purpose – verify microbial stability for the product life cycle
May predict issue before they are experienced in the market place
Questions considered: Is shelf life limited by a microbiological safety or quality concern? Is shelf-life testing feasible?
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End Product Testing
Demonstrate successful application of controls or assess the status of a lot when no other information exists.
Alternative sampling plans may be appropriate, for example: Fewer samples for on-going surveillance activity More samples when investigating significant process deviations or
outbreaks.
Questions considered: Is end product testing necessary to verify the overall manufacturing
process? Is end product testing relied upon for ensuring the safety or quality of
the lot?
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Example: Dried Ready-to-Eat Cereal
Relative importance Useful testing
Critical ingredients
Medium Test for mycotoxins if confidence in raw grains is lowTest nuts, cocoa, and other sensitive ingredients with no subsequent kill step for Salmonella if confidence in supplier is low.
In-process High Test appropriate product residues and in-line samples for Salmonella. Typical guidance levels:
Salmonella – absent
Processing environment
High Test for Salmonella and Enterobacteriaceae in the processing environment Typical guidance levels:
Enterobacteriaceae – 100-1000 cfu/g Salmonella – absent
Shelf-life Not relevant
-
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Example: Dried Ready-to-Eat Cereal (continued)
Relative importance Useful testing
End product
High Testing for Enterobacteriaceae is recommended to verify process control.
Product MicroorganismAnalytical method
Sampling plan & limits/g
Case n c m M
Dried cereal
Enterobacter-iaceae
ISO 21528-2
2 5 2 10 102
Low Testing for pathogens is not recommended during normal operation when GHP and HACCP are effective as confirmed by above tests. When above testing or process deviations indicate a possible safety issue, test for Salmonella.
Product MicroorganismAnalytical method
Sampling plan & limits/25g
Case n c m M
Dried cereals
Salmonella ISO 6579 11 10 0 0 -
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Example: Comminuted Meat
Relative importance Useful testing
Critical ingredients
Low to high
Pre-testing beef trimmings for E. coli O157:H7 may be useful when confidence in supplier control is low.
In-process Low Routine in-process samples are not normally collected. Samples of meat at various stages of processing can be used to establish a baseline and understand changes in the microbial population during processing.
Processing environment
Low Sample equipment surfaces before start-up to verify efficacy of cleaning and disinfecting. Typical levels encountered may vary by surface type.
Shelf life Low Routine shelf life testing of refrigerated raw meat is not recommended. Shelf life testing may be useful to validate code dates of new retail products or when new packaging systems are installed.
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Example: Comminuted Meat (continued)
Relative importance Useful testing
End pro-duct
Medium Test freshly packaged product for indicators for on-going process control and trend analysis using internally developed guidelines. Levels for processing do not apply during distribution or at retail.
Product MicroorganismAnalytical method
Sampling plan & limits/g
Case n c m M
Raw, comminuted meat
E. coli ISO 16649-2 4 5 0 0 -
Medium Routine testing is not recommended for salmonellae. In regions where ground beef is a continuing source of E. coli O157:H7 illness, the following criteria are recommended.
Product MicroorganismAnalytical method
Sampling plan & limits/25g
Case n c m M
Ground beef E. coli O157:H7 ISO 16654 14 30 0 0 -
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Microbial Sampling Summary
h Testing safety “into” products usually does not work because of sampling probability
h Testing is recommended to generate meaningful data Impact quality or safety Verify appropriate controls or direct corrective action
h Focus on verification of process control preferred Environmental monitoring Selected sampling tailored to the line to verify control
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Acknowledgements ICMSF Dr. Martin Cole, CSIRO, Australia (Chair)
Dr. Fumiko Kasuga, National Institute of Health, Japan (Secretary)
Dr. Jeff Farber, Health Canada (Treasurer)
Dr. Wayne Anderson, Ireland Food Safety Authority
Dr. Lucia Anelich, Consumer Goods Council, South Africa
Dr. Robert Buchanan, University of Maryland, United States
Dr. Jean-Louis Cordier, Nestle, Switzerland
Dr. Ratih Dewanti, Bangalore Agricultural University, Indonesia
Dr. Russ Flowers, Silliker Group, United States
Dr. Bernadette Franco, Universidade de São Paulo, Brazil
Dr. Leon Gorris, Unilever, China
Dr. Anna Lammerding, Public Health Agency, Canada
Dr. Xiumei Liu, CDC China
Dr. Tom Ross, University of Tasmania,, Australia
Dr. Katie Swanson, Ecolab, United States
Dr. Marta Taniwaki, Instituto de Tecnologia de Alimentos, Brazil
Dr. Marcel Zwietering Wageningen University, The Netherland
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Ecolab
Ecolab Global Research, Development and EngineeringEagan, Minnesota, USA