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

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.

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

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)

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

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

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

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).

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

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%

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

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

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.

Thank you for your attention! The financial support of TÁMOP-4.2.2/B-10/1 2010-0019 research grant is greatly acknowledged Thank you for your attention!