Although odour perception impacts food preferences, the effect of genotypic variation of odourant receptors (ORs) on the sensory perception of food is unclear, reported Kathrine Lunde from the Norwegian Meat Research Centre and co-authors there and at the University of Life Science in Ås, Nofima Mat and Duke University Medical Center in Durham, North Carolina, US.

In their paper published in PLoS ONE recently, they explain that androstenone, a steroid structurally related to testosterone, is a known pheromone in boars. Androstenone, in combination with skatole, makes up the primary component of boar taint, an unpleasant odour and flavour found in pork derived from male pigs. Previous research has revealed that almost all consumers have the ability to perceive skatole. a metabolite of intestinal bacterial flora in the lower gut, even at low concentrations. Androstenone occurs in pork from male pigs at levels up to 6.4ppm. Castration reduces the amount of androstenone in pork but the recent European Union proposal to ban castration due to animal welfare concerns has reinvigorated the study of consumer perception of pork containing androstenone.

Unlike skatole, perception of androstenone varies from person to person and some are highly sensitive and will react negatively upon exposure, according to the Norwegian group. A previous survey showed that 39 per cent of Norwegian consumers are identified as androstenone-sensitive.

The ability to perceive androstenone has been shown to correlate strongly with genetic variation in the human odour receptor OR7D4, according to Lunde and co–authors. The receptor responds to androstenone, and genotypic variation in OR7D4 predicts variation in the perception of androstenone. Since androstenone is naturally present in meat from male pigs, the researchers investigated whether OR7D4 genotype correlates with either the ability to detect androstenone or the evaluation of cooked pork tainted with varying levels of androstenone within the naturally occurring range.

Consistent with previous findings, subjects with two copies of the functional OR7D4 RT variant were more sensitive to androstenone than subjects carrying a non-functional OR7D4 WM variant.

When pork containing varying levels of androstenone was cooked and tested by sniffing and tasting, subjects with two copies of the RT variant tended to rate the androstenone-containing meat as less favourable than subjects carrying the WM variant.

The data is consistent with the idea that OR7D4 genotype predicts the sensory perception of meat containing androstenone and that genetic variation in an odourant receptor can alter food preferences, concluded Lunde and her co–authors.

Reference

Lunde K., B. Egelandsdal, E. Skuterud, J.D. Mainland, T. Lea, M. Hersleth and H. Matsunami. 2012. Genetic variation of an odorant receptor OR7D4 and sensory perception of cooked meat containing androstenone. PLoS ONE 7(5): e35259. doi:10.1371/journal.pone.0035259

Further Reading

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