Sensory perception of boar odour

Abstract

The research focussed on the sensory perception of boar odour; an odour problem that is sometimes present in the meat of entire male pigs and associated with two compounds namely skatole and androstenone. Researchers differ on the issue of the relative contributions of skatole and androstenone to the sensory perception of boar odour. The first objective of the research was to investigate the relative contribution of different concentrations of skatole and androstenone to the temporal perception of boar odour in boar fat. In South Africa, the potential for boar odour was regarded to be considerable should it be decided to discontinue the policy of castrating boars. However, the economic advantages associated with boar production on the other hand necessitated an investigation into consumer reactions to boar odour. The second objective was therefore to determine the effects of gender and ethnicity on consumer reactions to boar odour in boar fat samples with different concentrations of skatole and androstenone. Pork fat samples from 50 boars slaughtered at a commercial abattoir were analysed for skatole and androstenone concentrations and grouped within a 3 x 3 matrix representing low, medium and high levels of the odour compounds. A 10-member sensory panel, screened and trained to recognise and quantify skatole and androstenone odour intensities, was used to verify the human perception of boar odour in these pork fat samples immediately after heating (± 65°C) and following a cooling period of ten minutes (± 25°C). Consumers (n = 300) including equal numbers of males and females and from three ethnic groupings, namely blacks, whites and coloureds, were used to determine the effects of gender and ethnicity on consumer reactions towards boar odour compounds. Each consumer evaluated how much they would like to eat pork or pork products that smelled like the odour of each of 7 boar fat samples (65°C) with different combinations of known concentrations of skatole and androstenone. The consumers were recruited on two university campuses and the results can therefore not be extrapolated to the general South African population since the majority of the participants were young (18 - 35 years) and representing living standards measures (LSM) groups 6 to 8, i.e. the higher income groups. It was shown that the trained sensory panel differentiated the odour of the pork fat samples first and foremost on the basis of the presence or absence of androstenone and/or skatole odours and secondly on the character of the androstenone or skatole odour. Sensory perception of boar odour seems to have a temporal character which can be explained by differences in volatilisation (involving both odourant release and retention) of skatole and androstenone, possibly enhanced by differences in the properties of the fat matrixes of different samples. The temperature and time at which the samples were evaluated influenced both the intensity and the character of the perceived odour profiles. For samples with skatole concentrations above 0.25 µg/g and served warm, skatole was predominant while the influence of androstenone at levels above 0.5 µg/g and other odour components became increasingly important after samples had cooled down and skatole volatiles were less evident. The results showed that females compared to males would be less willing to consume pork and pork products with detectable levels of boar odour pertaining to both skatole and androstenone. All groups would be less willing to consume pork and pork products with detectable concentrations of skatole or skatole and androstenone in combination. An apparent liking for samples with medium levels of androstenone (0.5 to 1.0 µ/g) was found for some consumers, especially males, and can be partly attributed to the inability of some consumers to smell this component or a genuine liking for the odour of androstenone. Significant differences (p < 0.05) in the sensitivity of consumers from different ethnic groups were found with white females responding more negatively than white males and blacks. However, significant ethnic group effects were confounded by gender effects. The age of individuals, socio-economic factors and gender-linked personality factors may have influenced these differences. Although it was not possible to compare responses directly with the white and black groups because the samples were not identical, it was found that a higher percentage of coloureds responded negatively to boar odour compounds. Coloured males responded particularly negatively towards samples with detectable skatole, while black males, in general, were found to be more critical than black females. It was concluded that boar odour whether due to skatole, androstenone or both compounds in combination at the levels as currently found in South Africa, will contribute to negative consumer reactions, at least for the subsection of the population represented in the study. It was predicted that the majority of these consumers would be less willing to consume pork meat exhibiting detectable levels of boar odour. It was recommended that the policy of castration be continued until such time as methods have been developed to ensure reduction in both skatole and androstenone concentration levels of boars to levels that would not be detectable even to the most discerning of consumers.