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Copyrights © 2006 Silliker, Inc. All Rights Reserved
Practical Considerations in Method Selection
Copyrights © 2006 Silliker, Inc. All Rights Reserved
2
Overview
Background Consideration for the analysis
process Define criteria for method selection Selection Example – Indicator tests Summary
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3
Producing Safe Food is our First Priority
Consumer Protection & TrustConsumer trust Food Safety is critical to that trust
Business SurvivalOur brands are most important assets
Industry ResponsibilityCommitted to food safety across the
food chain
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4
Background
Testing is used as a tool to make decisions about the general state of a dynamic system.
Pathogen testing is used as a tool to make decisions about a dynamic system that has greater public health implications.
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U.S. Historical Perspective
Public health systems are representative of our general population shift (rural to urban
Before the 1870’s virtually all food produced and traded locally
Food mass production and transportation abilities changed quality and safety perceptions
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Historical Perspective
Need existed to regulate the safety of food
Regulations focused on dirt Massachusetts Health Act of 1797
Our current public health systems are still based on these principles
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Analysis Process
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Business factors to consider
Customer needs Operational Costs Lab complexity and layout
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Analytical Process Steps
Thinking / Planning Sampling Transport Testing Results Decision
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Where do we have method choices Sampling Transport Prep
Microbiological Chemical Physical
Incubation Testing Data Management
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Process Goal
Produce the best result possible System has been optimized and
the parts work together
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Decisions, Decisions, Decisions Conformance Fitness for use Communication
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Sampling
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What do we consider
Purpose Quality Safety Investigational
Risk Economics
How many and how much
Desired outcome
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Sampling Considerations
Matrix Analyte Distribution of target in matrix Lot size Storage
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Sampling
What is the matrix Liquid Powder Etc.
How large is the sample What is the container What are the temperature
requirements
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Transportation Issues
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Transportation – Key Parameters Identification
Sample can be easily identified Who What When Where How much
Preservation Sample maintained with minimal change in
intrinsic parameters
Protection Sample is protected from external
contaminants
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Sample Attributes
Microbiological levels Lipid Flavor Texture Nutrient composition
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What to consider in transport
Chemical composition of packaging material
Morphology of packaging polymer
Concentration of possible penetrants
Presence of co-permeant
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Environmental Factors
Temperature Relative humidity Packaging characteristics
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Preparation Consideration
Recover or measure a specific analyte
3 factor combination Matrix Analyte Test
Optimize for best outcome
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Incubation
Microbiological or Chemical Temperature Motion – static or shaking Atmosphere - air, microaerophilic, anaerobic
Optimize for best outcome
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Testing
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25
Testing
Key step in process Success is dependent on
previous steps Requires in depth planning Requires stringent quality
systems
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Testing Considerations
Product knowledge Previous use Cost and value Analysis performance
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Testing
Method Selection Analyte Matrix Time Money
Method Execution Receipt Prep Test Result
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Testing - Science Based Criteria Paramount importance to
execute each of these steps well Data used to make key public
health policy decisions Food Safety Objectives – FSO’s Listeria in RTE products Chemical contaminants in foods Allergen levels
Data used to make key corporate decisions
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Data Management
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General Data Uses
Safety assessment Pathogen Risk Qualitative and Quantitative data
Quality assessment Spoilage Risk Product Quality Qualitative and Quantitative data
Product and process improvement Criteria development Specification development
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Microbiological Data may be Used to Assess: The safety of food Verification/validation procedures in
HACCP Adherence to GMP/GHP The utility (suitability) of a food or
ingredient for a particular purpose The keeping quality (shelf-life) of
certain perishable foods Acceptability of a food or ingredient
from a source for which there is not confidence in the process
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32
Data Generation Assumptions
Methods validated For specific matrix
Quality system in place for analysis Analysts Facility Analysis tool
Sampling plans are appropriate
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33
Application Example – Indicator Testing
Application Example – Indicator Testing
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Definition of an Indicator
Webster’s defines an indicator as
“ an organism or ecological community so strictly associated with particular conditions that its presence is indicative of the existence of these conditions.”
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Definition of an Indicator Test
A test that accurately measures the organisms presence , absence or population count, thereby providing indirect evidence of a particular sample feature or condition
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Common Indicator Tests
TVC Coliforms Enterobacteriaceae Enterococci Lactics Yeast and Mold
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Common Indicator Tests
Psychrophilic counts Anaerobic counts Group Specific Pathogen Screens
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What is the test purpose
Distinguish good from bad Lots Pieces
Determine process changes Determine process approaching
control limits Rate product quality
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What is the test purpose
Determine inspection accuracy Check precision of the measuring
instrument Acquire product design information Measure process capability
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40
Selection Criteria
Measures what it is supposed to measure
Measurement correlates to a desired outcome
Results are easily interpreted Data is easy to manage
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Selection Criteria
Simple Deployable as close to process as possible Walk away use
Cost Effective Not necessarily “cheapest”
Rapid
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Indicator Acceptance Criteria
The organisms or conditions you measure have a “strong” relationship to a particular outcome or situation
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Test ImplementationTest Implementation
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Situational Assessment
Assess a problem/situation Determine your measurement needs Identify critical parameters Select measurement tool that gives
the best indication of significant change
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Method Assessment
Colony counts Direct detection
microscopy
Cellular component assessment ATP
Physiological properties Impedance/conductance
Metabolites toxins
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Test Assessment
Measurement Protocol Development Testing Validation
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Implementation and Decisions Use the test Collect data Monitor the results Test the system Analyze the data Use for decisions
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Summary
The analytical process is complex Understanding the importance of
each step and their relationships are key
Confidence is built by executing all of the steps well and highlights the need for stringent quality systems and procedures throughout the process
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49
Thank You !!Thank You !!
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References
Juran’s Quality Control Handbook, 4th edition; Juran, J.M. ,Gryna, Frank M.
Scientific Criteria To Ensure Safe Food, Institute of Medicine, National Research Council
Milestones in Microbiology ; Brock, Thomas Making Safe Food; Harrigan, W.F. , Park
R.W.A Evaluating The Measurement Process, 2nd
edition; Wheeler, Donald J. , Lyday, Richard W