Useful Microbiological Testing in Food Safety and Quality Management
1Useful MicrobiologicalTesting in Food Safety &Quality ManagementKatherine M.J. Swanson, Ph.D.Vice President Food Safety EcolabPresident-Elect IAFPArkansas Association for Food ProtectionSpringdale, ARSeptember 14, 2011
2Discussion Topics International Association for Food Protection greeting Different tests serve different purposes Testing for maximum value
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14Microbial 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 OR lotPresentation focuses on processcontrol and product acceptance
15The Purpose of a Test Determines:The target Indicator or pathogenThe method Time to results, accuracy, repeatability, etc. Environment, line residue, end product, locationThe sample collected, size/ number of samplesThe frequency Daily, weekly, monthly, etc. or event triggeredThe interpretation Investigational, routine, regulatory, etc. Rejection, process adjustment, recall, outbreakThe action investigation, etc.
16International Commission on MicrobiologicalSpecifications 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
17When & Where to Test for FoodSafety 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
18Target Organism ExamplesICMSF Hazard Categories EXAMPLESUtility Spoilage, reduced shelf life, no Total counts, yeast, mold, health concern etc.Indicator Measure of GHP or process control Coliforms, generic E. coli, Enterobacteriaceae, etc.Moderate Not life threatening, short duration, S. aureus, B. cereus, C.hazard self limiting, no sequelae perfringens, Norovirus, etc.Serious Incapacitating, usually not life Salmonellae, Shigellahazard threatening flexneri, Yersinia enterocolitica, etc.Severe Life threatening, chronic sequelae, E. coli O157:H7, Chazard or long duration OR botulinum toxin or Cronobacter (infants) Designed for sensitive sub- population From ICMSF Book 7
19Key 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
20Choosing m and M m M No concern Some Decisive concernRelative proportion of concern sample units in a lot Mean log count
21ICMSF Suggested Sampling Plans FOR LOT ACCEPTANCE TESTING Likely Change Before Consumption Hazard Group Reduce No Change Increase Utility Case 1 Case 2 Case 3 n=5, c=3 n=5, c=2 n=5, c=1 Indicator Case 4 Case 5 Case 6 n=5, c=3 n=5, c=2 n=5, c=1 Moderate Case 7 Case 8 Case 9 n=5, c=2 n=5, c=1 n=10, c=1 Serious Case 10 Case 11 Case 12unit = 25gAnalytical n=5, c=0 n=10, c=0 n=20, c=0 Severe Case 13 Case 14 Case 15 n=15, c=0 n=30, c=0 n=60, c=0
22Sample Size Influence on Probabilityof Acceptance m=0 1.2 Probability of Acceptance 86% n = 15 1 74% n = 30 0.8 55% n = 60 0.6 0.4 0.2 0 0 1% 5 10 15 20 % Defective
24Useful 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
25Process Example Process 1 Packaging Line A Ingredients Process 2 Packaging Line B Process 3 What action do you take when an unacceptable result is found on Line B?
26 Result Format Influences Information Provided Presence/Absence Quantative 5Positive 4 Log (CFU/g) 3 2 1Negative 0 0 10 20 0 10 20 Lot Number Lot Number
27Trend Analysis Can Inform ProcessControl 5 5 4 4 Log (CFU/g) Log (CFU/g) 3 3 2 2 1 1 0 0 0 10 20 0 10 20 Lot Number Lot Number 5 5 4 4 Log (CFU/g) Log (CFU/g) 3 3 2 2 1 1 0 0 0 10 20 0 10 20 Lot Number Lot Number
29Book 8 Contents Part 1-Principles Part 2 – Product Categories Utility of microbial testing for Meats safety & quality Poultry Validation of control measures Seafood Verification of process control Feed & pet food Vegetables Verification of environmental control Fruits Spices, dried soups, flavorings Corrective action to re-establish control Cereals Microbial testing in customer- Nuts, oilseeds, dried legumes supplier relationships 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
30Primary 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
31Ingredient 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?
32In-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?
33Processing 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?
34Shelf 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?
35End 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?
36 Example: Dried Ready-to-Eat Cereal Relative importance Useful testingCritical Medium Test for mycotoxins if confidence in raw grains is lowingredients Test 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 – absentProcessing High Test for Salmonella and Enterobacteriaceae in theenvironment processing environment Typical guidance levels: Enterobacteriaceae – 100-1000 cfu/g Salmonella – absentShelf-life Not - relevant
37 Example: Dried Ready-to-Eat Cereal (continued) Relative importance Useful testingEnd High Testing for Enterobacteriaceae is recommended to verify processproduct control. Analytical Sampling plan & limits/g Product Microorganism method Case n c m M Dried Enterobacter- ISO 2 5 2 10 102 cereal iaceae 21528-2 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. Sampling plan & Analytical limits/25g Product Microorganism method Case n c m M Dried Salmonella ISO 6579 11 10 0 0 - cereals
38 Example: Comminuted MeatRelative importance Useful testingCritical Low to Pre-testing beef trimmings for E. coli O157:H7 may beingredients high 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 Low Sample equipment surfaces before start-up to verifyenvironment 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.
39 Example: Comminuted Meat (continued) Relative importance Useful testingEnd Medium Test freshly packaged product for indicators for on-going processpro- control and trend analysis using internally developed guidelines.duct Levels for processing do not apply during distribution or at retail. Sampling plan & Analytica limits/g Product Microorganism l method Case n c m M Raw, comminuted E. coli ISO 16649-2 4 5 0 0 - meat 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. Sampling plan & Analytical limits/25g Product Microorganism method Case n c m M Ground beef E. coli O157:H7 ISO 16654 14 30 0 0 -
40Microbial Sampling Summary Testing safety “into” products usually does not work because of sampling probability Testing is recommended to generate meaningful data Impact quality or safety Verify appropriate controls or direct corrective action Focus on verification of process control preferred Environmental monitoring Selected sampling tailored to the line to verify control
41AcknowledgementsICMSF Dr. Martin Cole, CSIRO, Australia Dr. Russ Flowers, Silliker Group, United (Chair) States Dr. Fumiko Kasuga, National Institute of Dr. Bernadette Franco, Universidade de Health, Japan (Secretary) São Paulo, Brazil Dr. Jeff Farber, Health Canada Dr. Leon Gorris, Unilever, China (Treasurer) Dr. Anna Lammerding, Public Health Dr. Wayne Anderson, Ireland Food Agency, Canada Safety Authority Dr. Xiumei Liu, CDC China Dr. Lucia Anelich, Consumer Goods Council, South Africa Dr. Tom Ross, University of Tasmania,, Australia Dr. Robert Buchanan, University of Maryland, United States Dr. Katie Swanson, Ecolab, United States Dr. Jean-Louis Cordier, Nestle, Switzerland Dr. Marta Taniwaki, Instituto de Tecnologia de Alimentos, Brazil Dr. Ratih Dewanti, Bangalore Agricultural University, Indonesia Dr. Marcel Zwietering Wageningen University, The Netherland
42Ecolab Ecolab Global Research, Development and Engineering Eagan, Minnesota, USA