1. KAREN BEKAERT Ghent University Laboratory of Chemical Analysis Dpt. Veterinary Public Health and Food Safety Faculty of Veterinary Medicine The use of the hot iron method for the detection of boar taint Prof. L. Vanhaecke Dr. F.A.M. Tuyttens F. Vandendriessche

2. OUTLINE CURRENT SITUATION OBJECTIVES PRELIMINARY RESULTS TAKE HOME MESSAGES – FUTURE PERSPECTIVES 2 K.M. Bekaert – BOARS FOR 2018

3. OUTLINE CURRENT SITUATION OBJECTIVES PRELIMINARY RESULTS TAKE HOME MESSAGES – FUTURE PERSPECTIVES 3 K.M. Bekaert – BOARS FOR 2018

4. CURRENT SITUATION HOT - IRON METHOD Subjective method but “easy” to use in slaughterhouse and gains fast results Used by: Researchers Slaughterhouse NO RESEARCH ON IMPORTANT CHARACTERISTICS e.g. habituation, intra - and interreliability, position on the carcass, location in the slaughterhouse or in the laboratory K.M. Bekaert – BOARS FOR 2018 4

5. EXPERTS CURRENT SITUATION HOT - IRON USE OF THE HOT - IRON First singe the fat and afterwards smell Singe the fat and smell at the same time Habituation Type of hot-iron – temperature of the room/ fat K.M. Bekaert – BOARS FOR 2018 5

6. OUTLINE CURRENT SITUATION OBJECTIVES PRELIMINARY RESULTS TAKE HOME MESSAGES – FUTURE PERSPECTIVES 6 K.M. Bekaert – BOARS FOR 2018

7. “Evaluation” of the hot-iron method » Technical aspects » Heating methods » Cleaning » Singeing » Inter variability between experts » Intra variability of the experts » Habituation » Distribution of the compounds in the carcass OBJECTIVES K.M. Bekaert – BOARS FOR 2018 7

8. OUTLINE INTRODUCTION OBJECTIVES PRELIMINARY RESULTS TAKE HOME MESSAGES – FUTURE PERSPECTIVES 8 K.M. Bekaert – BOARS FOR 2018

9. EXPERTS : SAMPLES : – Select and collect in slaughterhouse – Stored at -20°C HEATING METHODS : – Hot-iron – Pyropen MATERIAL AND METHODS K.M. Bekaert – BOARS FOR 2018 9

10. SCORING : – Hot - iron Continous Converted to 0-100 scale – Laboratorium analyses strong poor medium no odour strongest imaginable MATERIAL AND METHODS K.M. Bekaert – BOARS FOR 2018 10

11. TECHNICAL ASPECTS – SAMPLES : 30 samples – HEATING METHODS A. HOT - IRON : 1.Wattage: 30 – 40 – 50 – 80 2.Brand: Ersa B. PYROPEN : Setting 1 & 3 – CONDITIONS A.Temperature of the sample: room or refrigerator B.Temperature of the area: room of refrigerator MATERIAL AND METHODS TECHNICAL ASPECTS K.M. Bekaert – BOARS FOR 2018 11

12. TECHNICAL ASPECTS Maximum temperature Theoretical (°C) Measuring at room temperature (22°C ± 1°C) Measuring at refrigerator temperature (5°C ± 1°C) Hot-iron 30W380281212 Hot-iron 40W420328285 Hot-iron 50W400373321 Hot-iron 80W410405348 Pyropen 350 – 500 (setting 1-5) 455 (setting 3) 371 (setting 3) 374 (setting 1) 328 (Setting 1) K.M. Bekaert – BOARS FOR 2018 TEMPERATURE DROPS BY MOVING THE HOT - IRON 12

13. Measuring at room temperature (22°C) Measuring at refrigerator temperature (5°C) Sample at room temperature (22°C°) Sample at refrigerator temperature (8°C) Hot-iron 30W 3.63.94.3sec 454032°C Hot-iron 40W 2.12.62.7sec 403428°C Hot-iron 80WBurned sec °C Pyropen (setting 1) 2.52.74.1sec 433630°C Pyropen (setting 3)Burned 2.52.9sec 3026°C TECHNICAL ASPECTS K.M. Bekaert – BOARS FOR 2018 13

14. COMPARISION BETWEEN EXPERTS – Time of scoring First singe the fat and afterwards smell » For every hot-iron same time (3.4 sec ± 0.5) Disadvantage: easier to burn the fat Singeing the fat and smell at the same time » Time depends on hot-iron wattage » Small differences between experts (± 0.5 sec) TECHNICAL ASPECTS K.M. Bekaert – BOARS FOR 2018 TECHNICAL ASPECTS 14

15. HEATING METHODS – SAMPLES : 32 samples – HEATING METHODS A.Microwave B.Hot-iron: 30 W C.Pyropen: setting 3 D.Pyropen + plate: setting 3 – CONDITIONS Temperature of the sample and area: room MATERIAL AND METHODS K.M. Bekaert – BOARS FOR 2018 HEATING METHODS 15

16. FRIEDMAN TEST PAIRWISE COMPARISON ( CORRELATION ) strong poor medium no odour strongest imaginable P<0.001 P1 P2P1 P2 M HI * MicrowaveHot-ironPyropen Hot-iron0.43 Pyropen0.530.50 Pyropen+plate0.500.520.46 HEATING METHODS P 1 : pyropen; P 2 : pyropen+plate; M: microwave; HI: hot-iron K.M. Bekaert – BOARS FOR 2018 HEATING METHODS 16

17. K.M. Bekaert – BOARS FOR 2018 HEATING METHODS KENDALL ’ S CORRELATION COEFFICIENT MicrowaveHot-ironPyropenPyropen+plate Indole0.26 * 0.39 ** 0.38 ** 0.20 Skatole0.25 * 0.40 ** 0.36 ** 0.16 Androstenone0.34 ** 0.37 ** 0.34 ** 0.35 ** HEATING METHODS Significant (* 0.05<p<0.01; ** 0.001<P<0.01) / not significant 17

18. CLEANING – SAMPLES : 120 samples – HEATING METHODS Hot-iron: 30 W – CONDITIONS Temperature of the sample and area: room – METHODS Cleaning the hot-iron with paper/ethanol Not cleaning the hot iron MATERIAL AND METHODS CLEANING K.M. Bekaert – BOARS FOR 2018 18

19. CLEANING SIGNED RANK TEST KENDALL ’ S CORRELATION COEFFICIENT strong poor medium no odour strongest imaginable P<0.001 cleaningnot cleaning CleaningNot cleaning Indole0.480.31 Skatole0.480.29 Androstenone0.300.27 CLEANING - SINGEING K.M. Bekaert – BOARS FOR 2018 CLEANING p<0.001 19

20. SINGEING – SAMPLES : 120 samples – HEATING METHODS Hot-iron: 30 W – CONDITIONS Temperature of the sample and area: room – SINGEING ONE FAT SAMPLE TWO TIMES AT THE SAME PLACE MATERIAL AND METHODS 1 and 2 singeing SINGEING K.M. Bekaert – BOARS FOR 2018 20

21. SINGEING SIGNED RANK TEST KENDALL ’ S CORRELATION COEFFICIENT strong poor medium no odour strongest imaginable P<0.01 firstsecond Firstsecond Indole0.490.30 Skatole0.430.31 Androstenone0.250.26 CLEANING - SINGEING K.M. Bekaert – BOARS FOR 2018 SINGEING p<0.001 21

22. OUTLINE CURRENT SITUATION OBJECTIVE PRELIMINARY RESULTS TAKE HOME MESSAGES – FUTURE PERSPECTIVES 22 K.M. Bekaert – BOARS FOR 2018

23. TAKE HOME MESSAGES TAKE HOME MESSAGES – FUTURE PERSPECTIVES K.M. Bekaert – BOARS FOR 2018 CHOICE OF HEATING METHOD – Significant difference between the methods – Highest values for microwave and hot-iron – Good correlation between the methods – Hot-iron and pyropen  best correlation with compounds USE OF THE HOT - IRON – Carefully choose wattage (room and sample temperature) – Necessary to clean the hot-iron – Never singe on the same place 23

24. Inter- and intra-variability of the experts  statistics Variation of the concentration of indole, skatole and androstenone inside a carcass FUTURE PERSPECTIVES TAKE HOME MESSAGES – FUTURE PERSPECTIVES K.M. Bekaert – BOARS FOR 2018 24

25. Agency for Innovation by Science and Technology (IWT-Vlaanderen) Imperial Meat Products VOF VION Food Group (NL) THANKS TO K.M. Bekaert – BOARS FOR 2018 25

26. THANKS TO K.M. Bekaert – BOARS FOR 2018 26

27. ??? K.M. Bekaert – BOARS FOR 2018 27