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

OUTLINE

• CURRENT SITUATION

• OBJECTIVES

• PRELIMINARY RESULTS

• TAKE HOME MESSAGES – FUTURE PERSPECTIVES

2 K.M. Bekaert – BOARS FOR 2018

OUTLINE

• CURRENT SITUATION

• OBJECTIVES

• PRELIMINARY RESULTS

• TAKE HOME MESSAGES – FUTURE PERSPECTIVES

3 K.M. Bekaert – BOARS FOR 2018

CURRENT SITUATION

CURRENT SITUATION

HOT-IRON METHODSubjective method but

“easy” to use in slaughterhouseand gains fast results

Used by:Researchers

SlaughterhouseNO 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 20184

• EXPERTS

CURRENT SITUATION

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

HabituationType of hot-iron – temperature of the room/ fat

K.M. Bekaert – BOARS FOR 20185

OUTLINE

• CURRENT SITUATION

• OBJECTIVES

• PRELIMINARY RESULTS

• TAKE HOME MESSAGES – FUTURE PERSPECTIVES

6 K.M. Bekaert – BOARS FOR 2018

“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

OBJECTIVES K.M. Bekaert – BOARS FOR 20187

OUTLINE

• INTRODUCTION

• OBJECTIVES

• PRELIMINARY RESULTS

• TAKE HOME MESSAGES – FUTURE PERSPECTIVES

8 K.M. Bekaert – BOARS FOR 2018

• EXPERTS:

• SAMPLES: – Select and collect in slaughterhouse – Stored at -20°C

• HEATING METHODS:– Hot-iron– Pyropen

MATERIAL AND METHODS

K.M. Bekaert – BOARS FOR 20189

• SCORING: – Hot - iron• Continous

• Converted to 0-100 scale– Laboratorium analyses

strongpoor medium

no odour strongest imaginable

MATERIAL AND METHODS

K.M. Bekaert – BOARS FOR 201810

• TECHNICAL ASPECTS– SAMPLES: 30 samples– HEATING METHODS

A. HOT-IRON: 1. Wattage: 30 – 40 – 50 – 80 2. Brand: Ersa

B. PYROPEN: Setting 1 & 3

– CONDITIONSA. Temperature of the sample: room or refrigeratorB. Temperature of the area: room of refrigerator

MATERIAL AND METHODS

TECHNICAL ASPECTS K.M. Bekaert – BOARS FOR 201811

TECHNICAL ASPECTS

TECHNICAL ASPECTS

Maximum temperature

Theoretical(°C)

Measuring at room

temperature (22°C ± 1°C)

Measuring at refrigerator

temperature (5°C ± 1°C)

Hot-iron 30W 380 281 212

Hot-iron 40W 420 328 285

Hot-iron 50W 400 373 321

Hot-iron 80W 410 405 348

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

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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 30W3.6 3.9 4.3 sec45 40 32 °C

Hot-iron 40W2.1 2.6 2.7 sec40 34 28 °C

Hot-iron 80W Burned Burned Burnedsec°C

Pyropen (setting 1)2.5 2.7 4.1 sec43 36 30 °C

Pyropen (setting 3) Burned2.5 2.9 sec30 26 °C

TECHNICAL ASPECTS

TECHNICAL ASPECTS K.M. Bekaert – BOARS FOR 201813

• 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 2018TECHNICAL ASPECTS 14

• HEATING METHODS– SAMPLES: 32 samples– HEATING METHODS

A. MicrowaveB. Hot-iron: 30 WC. Pyropen: setting 3D. Pyropen + plate: setting 3

– CONDITIONS• Temperature of the sample and area: room

MATERIAL AND METHODS

K.M. Bekaert – BOARS FOR 2018HEATING METHODS 15

FRIEDMAN TEST

PAIRWISE COMPARISON

(CORRELATION)

strongpoor medium

no odour strongest imaginable

P<0.001P1 P2 M HI

*

Microwave Hot-iron Pyropen

Hot-iron 0.43

Pyropen 0.53 0.50

Pyropen+plate 0.50 0.52 0.46

HEATING METHODS

P1: pyropen; P2: pyropen+plate; M: microwave; HI: hot-iron

K.M. Bekaert – BOARS FOR 2018HEATING METHODS 16

K.M. Bekaert – BOARS FOR 2018HEATING METHODS

KENDALL’S CORRELATION COEFFICIENTMicrowave Hot-iron Pyropen Pyropen+plate

Indole 0.26 * 0.39 ** 0.38 ** 0.20

Skatole 0.25 * 0.40 ** 0.36 ** 0.16

Androstenone 0.34 ** 0.37 ** 0.34 ** 0.35 **

HEATING METHODS

Significant (* 0.05<p<0.01; ** 0.001<P<0.01)/ not significant

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• 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 201818

• CLEANINGSIGNED

RANK TEST

KENDALL’S CORRELATION COEFFICIENT

strongpoor medium

no odour strongest imaginable

P<0.001cleaning not cleaning

Cleaning Not cleaning

Indole 0.48 0.31

Skatole 0.48 0.29

Androstenone 0.30 0.27

CLEANING - SINGEING

K.M. Bekaert – BOARS FOR 2018CLEANING

p<0.001

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• 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 201820

• SINGEINGSIGNED

RANK TEST

KENDALL’S CORRELATION COEFFICIENT

strongpoor medium

no odour strongest imaginable

P<0.01firstsecond

First second

Indole 0.49 0.30

Skatole 0.43 0.31

Androstenone 0.25 0.26

CLEANING - SINGEING

K.M. Bekaert – BOARS FOR 2018 SINGEING

p<0.001

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OUTLINE

• CURRENT SITUATION

• OBJECTIVE

• PRELIMINARY RESULTS

• TAKE HOME MESSAGES – FUTURE PERSPECTIVES

22 K.M. Bekaert – BOARS FOR 2018

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

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• 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

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• Agency for Innovation by Science and Technology (IWT-Vlaanderen)

• Imperial Meat Products VOF

• VION Food Group (NL)

THANKS TO

THANKS TO K.M. Bekaert – BOARS FOR 201825

THANKS TO

THANKS TO K.M. Bekaert – BOARS FOR 201826

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