Mycotoxin Sampling in Food Commodities

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1 Mycotoxin Sampling in Food Commodities Andrew Slate USDA-ARS (Retired) North Carolina State University FAO 1

2 Challenge? Seller Buyer Mycotoxin Concentration? 2

3 Mycotoxin Distribution Among Kernels (Rare Event) Lot Aflatoxin Concentration = 10 ppb Contamination rate = 3/10,000 = 0.03% 3

4 Lot Sample (5 kg) (50,000 kg) PPB=? ppb Lot PPB = Sample ppb Sample ppb Maximum Level 4

5 U.S. Dept. of Agriculture Aflatoxin Inspection 3x5kg samples ppb What is wrong? 5

6 Aflatoxin/Shelled Corn 1.1 kg 20 ppb Mean = Median = x 1.1 kg Samples

7 Aflatoxin/Shelled Corn 1.1 kg 20 ppb Lot Mean = 25 Median Mean=25 = 19.5 Variance=612.8 Median= x 1.1 kg Samples

8 Sampling Protocol - Plan Elements A. Test procedure 1) Laboratory sample size, number 2) Sample preparation type mill (grinding) test portion size 3) Analytical method number aliquots B. Accept/Reject limit 8

9 Lot Mycotoxin Test Procedure Mill Sample Sample Analysis Preparation Acc/Rej Limit > Test Result - ppb 9

10 No Biases with Mycotoxin Test Procedure (Sampling, Sample Prep, & Analysis) Representative Sample (No Bias) Every kernel has an equal chance of being chosen Random selection process Note: Inherent sampling variability is not eliminated by selecting representative samples 10

11 Sample Selection Static and Dynamic Lots Minimum recommended increment size 200 g Maximum recommended sampling rate 1 increment every 400 kg 11

12 Dynamic Lots (Peanuts in Motion) Processing lines Conveyors Elevators Packaging hoppers 12

13 Shelled Peanuts on Conveyor 13

14 In-line Automatic Sampler Conveyor Belt Product Sample Cup 14

15 In-line Automatic Sampler 15

16 Static Lots (Peanuts not in Motion) Sacks & boxes Transport containers Retail packaging 16

17 How to take a representative sample? 17

18 Super Sack 1000 kg 18

19 Vacuum Sampler Removable Probe 19

Probing Locations / Increments 9 8 3 4 5 ~2 kg / probe 1

20 Probing Locations / Increments ~2 kg / probe 1 probe / sack ~40 kg aggregate Top View of Sack 20

21 Pneumatic Sampler Inshell Peanuts 21

22 Manual Probe Hand Trier 22

23 Sample Selection Summary Sampling is generally a large source of testing variability Variability statistics are only valid for representative sample Critical sampling components Sample size Sample selection 23

24 Take Incremental Samples from Many Locations in the Lot (100x200g) Aggregate Sample Divider Lab. Sample Excess 24

25 Rotary Divider Riffle Divider 25

26 Comminute ENTIRE laboratory sample Comminuted laboratory sample may not be homogeneous so divider must be used to obtain representative test portion Lab. Sample 0.5 kg 20 kg Grinder Divider Excess Test Portion 5 g -100 g 26

27 Uncertainty Sampling Error Total Error Sample Preparation Error Analytical Error Lot Sample Preparation Analysis ppb 27

28 Sampling Error Lot ppb Sample Preparation Error 0 Sample Values (ppb) 80 Sample ppb Analytical Error 0 Subsample Values (ppb) Subsample ppb 80 0 Analytical Values (ppb) 80 28

29 Reduce Variability Sampling Increase sample size Sample Preparation Finer grind Increase test portion size Analytical Increase # measurements Improve technology 29 29

30 Variability Leads to Misclassification of Lots Good lots rejected (Seller s risk) Bad lots accepted (Buyer s risk) 30

31 Lot Shelled Corn at 20 ppb Aflatoxin Test Procedure Variance Ratio (%) 1 kg Romer, 50 g HPLC, 1 al Total

32 Lot Shelled Corn at 20 ppb Aflatoxin Test Procedure Variance1 Variance2 Sample 1 kg kg 80.6 Romer, 50 g g 28.2 HPLC, 1 al al. 2.3 Total

33 Sampling Plan Evaluation Method (Design Performance) Test Procedure Acc/Rej Limit (Reg. Limit) Variability Distribution Theory Seller s Risk Buyer s Risk Mycot. Removed Cost 33

34 GOOD Accept BAD Accept x (Buyer s Risk) Reject (Seller s Risk) x Reject 0 Reg Limit Lot Concentration (ppb) High 34

35 Lots Accepted (%) 100 Good Bad 0 0 Reg Limit Lot Concentration (ppb) High 35

36 Lots Accepted (%) 100 GLR Seller s Risk BLA Buyer s Risk 0 0 Reg Limit ppb Lot Concentration (ppb) 36

37 Lot 1 Lot i Lot 20 Sample 1 10 kg Sample j 10 kg Sample kg Water Slurry Test Portion 1 55 g Test Portion 2 55 g Extract Extract Aliq 1 Aliq 2 Aliq 1 Aliq 2 A i,j,1,1 A i,j,1,2 A i,j,2,1 A i,j,2,2 37

38 Mycotoxin/Commodity Sampling Studies Variance components Distribution determination OC curves generated Grains Peanuts Treenuts Others Mycotoxin Aflatoxin Fumonisin DON Ochratoxin A Website for Publications: 38

39 Probability of Accept (%) Shelled Peanuts Tolerance 1x5.5 kg 25 ng/g 1x11 kg 25 ng/g 1x22 kg 25 ng/g kg 11kg 22kg Lot Aflatoxin Concentration (ng/g AFT) 39

40 Probability of Accept (%) Shelled Peanuts Tolerance 1x22 kg 25 ng/g 1x22 kg 20 ng/g 1x22 kg 15 ng/g ng/g 20 ng/g 25 ng/g Lot Aflatoxin Concentration (ng/g AFT) 40

41 Probability of Accept (%) 100 Shelled Peanuts x10 Tolerance 1x10 kg 2B1/4T 2x10 kg 2B1/4T 3x10 kg 2B1/4T 3x10 2x Lot Aflatoxin Concentration (ng/g AFT) 41

42 Probability of Accept (%) 100 Shelled Peanuts Tolerance 1x30 kg 2B1/4T 3x10 kg 2B1/4T 3x10 1x Lot Aflatoxin Concentration (ng/g AFT) 42

43 Number of Lots Total Lots Shelled Corn in a Bad Crop Year Rejected Accepted Testing Plan - 1 x 5 kg g test portion - HPLC 1 aliquot Lot Aflatoxin Conc. 43

44 Number of Lots Total Lots Shelled Corn in a Good Crop Year 200 Rejected Accepted Testing Plan - 1 x 5 kg g test portion - HPLC 1 aliquot Lot Aflatoxin Conc. 44

45 Decisions Risk levels vs cost Select sampling plan design elements for stated risks Uniform design across industry Test procedure Maximum level Where to sample in supply chain Mandatory or voluntary Conduct sampling study 45

46 Consequences Lower mycotoxin levels in products Increased customer satisfaction Higher costs of doing business Increased use of prevention and decontamination strategies Creation of a mycotoxin test result database 46

PROPER SAMPLING ONE SIZE DOESN'T FIT ALL!

PROPER SAMPLING ONE SIZE DOESN'T FIT ALL! ERIN BOWERS IOWA STATE UNIVERSITY Postdoctoral Research Associate IMPORTANT CONCEPTS Sampling is predetermined What is the purpose of taking that sample? Method