1. Classification of meat with boar taint using an electronic nose
Agnes KIRSCHING,
Gy. BAZAR, Z. HAZAS, R. ROMVARI

2. Boar taint odor
Meat from young boars (uncastrated male pigs) can present a distinctive unpleasant odor, known as boar taint, wich is detected during cooking and eating.

3. Boar taint odor substances
Androstenone Skatole
Vold, 1970;
Walstra & Maarse, 1970
Deposited in the fat
Product of the bacterial degra-
dation of tryptophan in the gut
Fecal odour
Treshold value 0.21 µg/g fat
Patterson, 1968
Deposited in the fat
Testicular steroid
Urinary odour
A part of the human population is insensible
Treshold value 1.0 µg/g fat

4. Detection methods of boar taint
Chemical methods:
Several methods: colorimetric, chromatographic, immunological
Not applicable on the slaughter line
Complicated sample preparation
Labor and time demanding
Human sensory method:
Mainly used in slaughter houses the
cooking/melting tests
It is subjective
At the present there is no on-line method for detecting and sorting out the boar tainted carcasses at the slaughter line.
New possibilities the chemical gas sensor arrays,
Electronic Noses (EN)

5. Aim of the study
To test the applicability of electronic nose (EN) instrument for a discrimination of boar tainted samples of different meat parts.

6. Samples and preparation
Pork chops from two entire male pigs with definite boar odor.
Five different carcass parts:
loin
neck
shoulder
other thigh
inner thigh
Meat samples of the two animals were
cut into pieces and mixed
heated for 1 hour at 75 ºC
homogenized. Human sensory analysis
EN measurement

7. Electronic nose (EN) measurement
Sample preparation for EN
1 g homogenised pork meat + 1 ml of dilution into vials; closed with silica septa
20 parallels for each carcass parts (n=5×20)
Headspace analysis
An αFox 4000 (ALPHA MOS,
Toulouse, France) type EN with
18 metal oxide sensors (MOS)
in 3 chambers was used.
Sample temp.
Equilibration time
Injection volume
Injection speed
Flow rate
80 ºC
180s with agitation
3000μl
500μl/s
150ml/min
Data evaluation
AlphaSoft V.12 software
SPSS 16 software package

8. Human sensory analysis procedure
The sensory analysis procedure (n=11)
The feshly cooked and homogenized meat samples were placed on the coded and covered plates.
Panelists were required to rate the boar taint intensity of samples on 9 cm undivided line scale.
Selection of panelists,
the training (n=17)
Androstenone sensitivity
of panelist was tested
by triangle test
(Lunde et al. , 2009).

9. Results of human sensory analysis
Result of androstenone sensitivity test:
Among 17 panellists (12 women, 5 men) 4 (23.5%) were insensitive to androstenone.
The average boar taint score values by the human sensory panel (n=11)
 Samples
Boar taint
Loin (1)
1.81
Neck (2)
3.25
Shoulder (3)
2.43
Thigh outer (4)
2.63
Thigh inner (5)
2.37

10. Results of EN measurement
Discrimination of the five meat samples using all EN sensors determined by the 1st and 2nd discriminant function
loin
neck
shoulder
outer thigh
inner thigh
The first 2 function describing 97.2% of the total variance.
Correctly classified samples: 94.8%
Cross-validation: 83.3%

11. Results of EN measurement
Discrimination of the meat samples using stepwise method
9 sensors (LY2/LG, LY2/G, LY2/AA, LY/gCT, P10/2, P40/1, T70/2, P30/1, P40/2) were chosen by the stepwise optimization method, and only these were involved in the DA.
Correctly classified samples: 91.7%
Cross-validation: 86.5%
Cross-
validation
Loin
Neck
Shoulder
Outer Thigh
Inner Thigh
Total 15 2 17 20 4 19
Outer thigh 3 16 1
Inner thigh

12. Correlation between sensory panel and EN responses to boar taint
Association between predicted (PLS) and reference (sensory panel) values of boar taint, based on EN data and human nose score obtained for the different meat parts
R2=0.92
thigh inner
neck
thigh outer
loin
shoulder

13. Conclusions
Based on the results of sensory panel it can be concluded that the intensity of boar taint perception increases with increasing level of fat content.
The EN is able to discriminate with high accuracy different meat parts presenting different levels of boar taint.
The EN responses were successfully calibrated against sensory panel scores.

14. Thank you for your attention!
The financial support of TÁMOP-4.2.2/B-10/ research grant is greatly acknowledged
Thank you for your attention!