A significant part of the quality (perceived and health) of virgin olive oil is assessed based on the bitterness and pungency as these qualities indicate a high phenolic content in the oil. It is the phenolic compounds contained in virgin olive oil that are believed to contribute to the the low incidence of chronic inflammatory disease observed in Mediterranean populations.
Good quality virgin or extra virgin olive oil has a distinct sensory quality which has been attributed to one particular phenolic compound, oleocanthal. This distinct pungency is restricted to the throat which is unusual, as most irritants will stimulate other areas in the mouth, nose, eyes…. Oleocanthal shares this perceptual characteristic with ibuprofen, a non-steroidal anti-inflammatory drug, and also targets the same inflammatory pathway as ibuprofen. Both oleocanthal and ibuprofen inhibit cyclooxygenase enzymes which are inflammatory enzymes.
The throat irritation produced from oleocanthal and ibuprofen is variable amongst individuals and this is attributed to the specificity of these compounds to the Transient receptor potential cation channel, subfamily A, member 1 (TRPA1). It is a protein that in humans is encoded by the TRPA1 gene. TRPA1 is anion channel located on the plasma membrane of many human and animal cells and higher proportions of TRPA1 are located in the throat..
Therefore oleocanthal and ibuprofen produce a localised irritation where as other irritants such as capsaicin (the heat component of chilli peppers) irritate other areas of the oral cavity. Capsaicin is the prototypical TRPV1 agonist. The function of TRPV1 is primarily detection and regulation of body temperature. Additionally, TRPV1 receptor provides sensation of scalding heat and pain (also known as nociception).
A recent study conducted by Bennett and Hayes (2012) aimed to quantify the overall intensity of oleocanthal in olive oil and ibuprofen while also investigating predominant and secondary sub qualities and then compared them to capsaicin. Bennett and Hayes (2012) add to the molecular data with behavioral evidence that olive oil and ibuprofen differ from capsaicin in receptor specificity as capsaicin does not activate TRPA1 receptor. However of interest, although olive oil and ibuprofen differ from capsaicin in intensity of irritation ratings there is a correlation between olive oil and capsaicin in chemesthetic subqualities (e.g., burn, warm, hot). This would indicate that an unknown compound in olive oil is a TRPV1 agonist.
These authors conclude that Ibuprofen and capsaicin had independent sub qualities while olive oil is an intermediate and shares qualities with both ibuprofen (numbing, tickling) and capsaicin (burning, warming). There are a number of limitations when gathering meaningful qualitative data on irritant sensations, as irritant qualities such as tickling, itching etc are hard to characterize. Therefore future studies should focus on suitable descriptive qualities of irritant compounds such as ibuprofen, oleocanthal and capsaicin, that produce these sensations.