Ghent University Laboratory of Chemical Analysis Dpt. Veterinary Public Health and Food Safety

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

2. outline • current situation • objectives • preliminary results • take home messages– futureperspectives K.M. Bekaert – boars for 2018

3. outline • current situation • objectives • preliminary results • take home messages– futureperspectives K.M. Bekaert – boars for 2018

4. current situation hot-ironmethod Subjectivemethodbut “easy” to use in slaughterhouse and gainsfastresults Usedby: ResearchersSlaughterhouse • no research on important characteristics • e.g. habituation, intra - and interreliability, positionon the carcass, location in the slaughterhouse or in the laboratory K.M. Bekaert – boars for 2018 current situation

5. current situation • experts • hot-iron • use of the hot-iron • First singe the fat and afterwards smell • Singethe fat and smell at the same time Habituation Type of hot-iron – temperature of the room/ fat K.M. Bekaert – boars for 2018 current situation

6. outline • current situation • objectives • preliminary results • take home messages– futureperspectives K.M. Bekaert – boars for 2018

7. objectives “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 K.M. Bekaert – boars for 2018 objectives

8. outline • introduction • objectives • preliminary results • take home messages– futureperspectives K.M. Bekaert – boars for 2018

9. material and methods • experts: • samples: • Select and collect in slaughterhouse • Stored at -20°C • heatingmethods: • Hot-iron • Pyropen K.M. Bekaert – boars for 2018

10. material and methods • scoring: • Hot - iron • Continous • Converted to 0-100 scale • Laboratorium analyses strong poor medium noodour strongest imaginable K.M. Bekaert – boars for 2018

11. material and methods • technicalaspects • samples: 30 samples • heatingmethods • hot-iron: • Wattage: 30 – 40 – 50 – 80 • Brand: Ersa • pyropen: Setting 1 & 3 • conditions • Temperature of the sample: room orrefrigerator • Temperature of the area: room of refrigerator K.M. Bekaert – boars for 2018 technical aspects

12. technical aspects temperature drops by moving the hot-iron K.M. Bekaert – boars for 2018 technical aspects

13. technical aspects K.M. Bekaert – boars for 2018 technical aspects

14. technical aspects • 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) K.M. Bekaert – boars for 2018 technical aspects

15. material and methods • heating methods • samples: 32 samples • heating methods • Microwave • Hot-iron: 30 W • Pyropen: setting 3 • Pyropen + plate: setting 3 • conditions • Temperature of the sample and area: room K.M. Bekaert – boars for 2018 heating methods

16. heating methods friedman test pairwise comparison (correlation) * P<0.001 p1 p2 m hi strong poor medium strongest imaginable no odour P1: pyropen; P2: pyropen+plate; M: microwave; HI: hot-iron K.M. Bekaert – boars for 2018 heating methods

17. heating methods kendall’s correlation coefficient Significant (* 0.05<p<0.01; ** 0.001<P<0.01)/ not significant K.M. Bekaert – boars for 2018 heating methods

18. material and methods • 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 K.M. Bekaert – boars for 2018 cleaning

19. cleaning - singeing • cleaning signed rank test kendall’s correlation coefficient P<0.001 cleaning not cleaning strong poor medium strongest imaginable no odour p<0.001 K.M. Bekaert – boars for 2018 cleaning

20. material and methods • 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 1 and 2 singeing K.M. Bekaert – boars for 2018 singeing

21. cleaning - singeing • singeing signed rank test kendall’s correlation coefficient P<0.01 second first strong poor medium strongest imaginable no odour p<0.001 K.M. Bekaert – boars for 2018 singeing

22. outline • current situation • objective • preliminary results • take home messages– futureperspectives K.M. Bekaert – boars for 2018

23. take home messages • 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 K.M. Bekaert – boars for 2018 take home messages – future perspectives

24. future perspectives • Inter- and intra-variability of the experts  statistics • Variation of the concentration of indole, skatole and androstenone inside a carcass K.M. Bekaert – boars for 2018 take home messages – future perspectives

25. thanks to • Agency for Innovation by Science and Technology (IWT-Vlaanderen) • Imperial Meat Products VOF • VION Food Group (NL) K.M. Bekaert – boars for 2018 thanks to

26. thanks to K.M. Bekaert – boars for 2018 thanks to

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