BACKGROUND
Boar taint is an unpleasant odour and flavour released during heat treatment of pork from uncastrated male pigs, mainly due to androstenone and skatole. Because surgical castration of male piglets is increasingly challenged on animal welfare grounds, feeding entire males is an important alternative, but it raises concern about boar taint. Androstenone is produced in the testes and has high heritability, whereas skatole is generated by microbial degradation of tryptophan in the hindgut and is more influenced by environmental factors such as diet. Hydrolysable tannins have attracted interest because they may reduce intestinal skatole production, but prior work focused mostly on growth, carcass traits, meat quality, and fat concentrations of boar-taint compounds rather than sensory eating quality. This study therefore examined whether dietary supplementation with sweet chestnut wood extract (SCWE) rich in hydrolysable tannins affects skatole and androstenone accumulation in adipose tissue and the sensory properties of pork from entire male pigs, while also considering whether panellist sex influences sensory ratings.
METHODS
The experiment included 80 young boars, progeny of Landrace sows and Yorkshire × Pietrain boars. Pigs were randomly assigned within litters to 1 control group and 4 treatment groups, with 16 animals per group. The control group (T0) received a standard diet without tannin supplementation. The treatment groups received the same diet supplemented with 10 (T1), 20 (T2), 30 (T3), or 40 (T4) g/kg SCWE, corresponding to 1%, 2%, 3%, and 4% supplementation. The Farmatan product contained 73 ± 2% tannins according to the producer, and total phenolic content measured by the Folin–Ciocalteu method was 45.1%. Supplementation started when boars reached an average live weight of 80 kg and continued for 40 days before slaughter. Pigs were slaughtered in one batch at an average live weight of 122.28 kg ± 5.63 kg. After 24 h of chilling, musculus longissimus thoracis samples with subcutaneous fat were collected for sensory analysis. Samples were thawed overnight at 4 °C, trimmed to 5 mm of subcutaneous fat, grilled for 4 min at 180 °C, and reached an average internal temperature of 80 °C. Sensory evaluation was conducted by 20 selected panellists (12 men and 8 women aged 32 to 60 years old) who ate pork regularly and were screened for androstenone sensitivity. In total, 320 samples were evaluated in 8 sessions, each consisting of 40 evaluations. Panellists scored odour, flavour, tenderness, and juiciness on a 5-point scale, with 1 as the worst and 5 as the best. Fat samples from the belly were analysed for androstenone and skatole by gas chromatography-mass spectrometry. Detection limits were 0.02 µg/g for androstenone and 0.01 µg/g for skatole. Statistical analysis used 1-way ANOVA for androstenone and skatole and 2-way ANOVA for sensory traits, with Pearson correlations calculated between boar-taint compounds and sensory traits.
KEY RESULTS
Tannin supplementation did not affect androstenone deposition in adipose tissue. In contrast, the authors reported a numerical reduction in skatole concentration in fat tissue after 2%, 3%, and 4% tannin supplementation compared with the control group, although this was nonsignificant, with p = 0.052–0.055. Looking at threshold-based classification, samples high in both androstenone and skatole levels, defined as greater than thresholds of 1.0 and 0.2 µg/kg, respectively, numbered 5 in the control group and 1, 2, 3, and 0 in the T1, T2, T3, and T4 groups, representing 31.25%, 6.25%, 12.5%, 18.75%, and 0%, respectively. The total number of samples high in androstenone, skatole or both compounds was 10 (62.5%) in controls, and after tannin supplementation these numbers were reduced to 7%, 6%, 8% and/or 7% (43.75, 37.5, 50.0 and/or 43.75%). Correlations between adipose boar-taint compounds and sensory traits were generally small and negative. The paper states that higher correlations were observed between skatole and eating quality parameters, except for juiciness, which was more correlated with androstenone concentration.
Sensory analysis showed no effect of tannin supplementation on odour or flavour. However, tenderness and juiciness differed significantly among treatment groups. Men rated both traits significantly better in pork from the control group than in meat from T3–T4 or T4: tenderness was 3.05 vs. 2.74 and 2.81, and juiciness was 3.28 vs. 2.75, p < 0.05. Women were more critical than men overall, regardless of diet group. For tenderness, women scored 2.70 vs. 3.00 for men, p < 0.05. For juiciness, women scored 2.65 vs. 2.99 for men, p < 0.01. The abstract and discussion both emphasize that reduced tenderness and juiciness at higher tannin doses were sex-dependent and observed mainly in men’s evaluations.
CLINICAL IMPLICATIONS
This was not a human clinical study, but it has practical implications for animal production, food quality, and welfare-oriented pork systems. The data suggest that hydrolysable tannins may help reduce skatole accumulation, especially at 2%–4% supplementation, without affecting androstenone. Because odour and flavour were unchanged, lowering skatole alone did not translate into clearly better perceived eating quality under these study conditions. Higher doses, particularly 3%–4%, may worsen tenderness and juiciness, which could offset any benefit in boar-taint reduction. The sex-dependent differences in panel scoring also indicate that consumer perception can vary systematically and should be considered in sensory studies. Overall, the findings support further work to define an optimal tannin dose that lowers skatole while preserving texture and eating quality in pork from entire males.