Because for many people the corianderknown as Chinese parsley or cilantro, tastes like soap or of bug? When we eat coriander, a lot of aromas are released in the mouth, that is, molecules that evaporate, reach the nose, interact with the olfactory receptors and therefore contribute to the flavour. At the basis of the subjective perception of the flavor of coriander are the genetics and the eating habits. Some aldehydes contained in this plant are perceived differently depending on the genetic variant of an olfactory receptor that each of us possesses.
The coriander (Coriandrum sativum) is an annual aromatic plant of the Apiaceae family, the same as the parsleydel fennel and of thedill. Originally from the Mediterranean area and the Middle East, it presents itself with bright green leaves and stems that can reach 60-70 cm in height and approximately 20 cm in diameter. Known and appreciated for millennia, the Romans already used it to flavor bread, this species is still cultivated in different areas of the world also thanks to its ability to resist different climatic conditions. Today, it is the protagonist of many culinary specialties, especially in Latin America, China and India. Two parts of the plant are used, i seeds used as a spice (yellow-brown in color and spherical in shape) and the leaves used as aromatic herbs.
The leaves themselves have a complex aromatic profile. They contain different aldehydesincluding the trans-2-decanal and the 13-tetradecenal. These molecules are responsible for that particular “soapy” aftertaste that some perceive and which is reminiscent of the smell emitted by bedbugs.
Not all people have olfactory receptors in their nose to sense these molecules. So those who don’t have these receptors won’t feel these molecules and maybe even find it pleasant, citrusy. Those who have these receptors, however, perceive the molecules and perhaps find it unpleasant.
Why do some people have these receptors and others don’t? Most likely it is for a matter genetics. In the DNA there are some genes that allow us to have these receptors, therefore to smell these aromas. The biological mechanism it may have been identified by genetic research (Eriksson et al., 2012) which indicated the gene as the “cause” of the soap smell OR6A2. This gene codes for an olfactory receptor that is highly sensitive to aldehyde chemicals (the ones that give cilantro its flavor). Who has specific variants (SNP – single nucleotide polymorphism) of this gene has an altered and amplified perception of these molecules.
The genetic component has an impact but is not the only protagonist: also the context socio-cultural and the eating habits play an important role. A study published in the journal Flavour analyzed the spread of the phenomenon around the world. The researchers found that disgust was much more common among East Asians (21%) they Europeans (17%). On the contrary, aversion drops drastically (between 3% and 7%) in populations that massively use coriander in their culinary tradition, as in South Asia or in Latin America.
Even those who are initially disgusted can get used to the flavor with time and frequent exposure. It’s the same mechanism that happens with other foods with a strong and divisive flavor, such as coffee, truffles or ginger.
