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7 min
08/09/2026
Ever wondered why cilantro tastes like soap? The cilantro taste is not identical for everyone. For some people, volatile aldehydes in fresh coriander leaves trigger stronger perceptions of soapiness or pungency. Genetic differences involving the olfactory receptor OR6A2 can influence this response, while retronasal smell helps turn aroma into the flavour experienced while eating.
The reason why cilantro tastes like soap or gives a soapy impression is mainly an olfactory phenomenon rather than a simple difference in the tongue’s taste buds. Cilantro releases several aldehydes, including decanal and unsaturated aldehydes, that contribute to its characteristic aroma. Variations in OR6A may alter sensitivity to some of these molecules, helping explain why the same herb can taste bright and citrusy to one person yet intensely soapy to another.
The reason cilantro tastes like soap to some people has a scientific basis, although it doesn’t mean that soap itself is being tasted. This herb contains many volatile compounds, known as aldehydes, that produce odours such as green, oily, pungent, and soapy.
Scientific studies have also confirmed that aldehyde compounds such as decanal and (E)-2-decenal can be detected in coriander leaves. Also, the olfactory receptor OR6A2 responds to medium-chain aldehydes, which are associated with the soapy taste experience.
This means the phenomenon has more to do with smell than with the actual taste sensations provided by the tongue.
The nose contains olfactory receptors that allow us to detect different airborne chemical compounds. When a person smells cilantro directly, this refers to orthonasal olfaction. During eating, chewing releases volatile compounds into the mouth, and exhaling carries them to the back of the throat and into the nasal cavity. This phenomenon, known as retronasal olfaction, is one of the key components of flavour.
The importance of making this distinction arises from the fact that the brain processes these pathways differently. Studies show that retronasal smells can stimulate brain regions involved in taste perception, thereby enabling the perception of aroma as taste. Therefore, someone may describe the herb as having a soapy “taste” even though a major part of that sensation originates through the nose.
The tongue identifies basic taste modalities through the activation of receptors that transmit sensations of sweetness, saltiness, sourness, bitterness, and savoury taste. It does not distinguish complex taste sensations, such as the cilantro taste or soap-like taste. Such perceptions develop when the signals from other sensory systems are processed in the brain.
Cilantro can elicit taste and oral sensations. But the distinctive sense of cilantro relies mainly on volatile compounds that act on our olfactory system. Thus, a decrease in the smell intensity of substances will significantly reduce the overall perception of their flavour since a large part of flavour perception occurs through retronasal olfaction.
A recent genome-wide association study involving over 26,000 individuals has identified a correlation between cilantro preference or aversion and a genetic variant near the OR6A2 olfactory receptor gene. This does not imply that input from a single gene is sufficient to explain food aversion or preference.
Earlier research has also identified associations between cilantro perception and variants in other chemosensory genes. This broader evidence supports a more nuanced conclusion: sensory perception is partly biological, but it is not governed by a single genetic switch. Familiarity, exposure and individual differences in smell perception can also shape food preferences.
Sensory system |
What it detects |
Role in cilantro taste |
Taste |
Basic taste qualities |
Adds gustatory information |
Olfaction |
Volatile molecules |
Detects aroma compounds |
Retronasal olfaction |
Food aromas during eating |
Helps create flavour perception |
Oral somatosensation |
Texture and temperature |
Adds physical mouth sensations |
This explains why two people can eat the same herb and report dramatically different experiences. Their sensory systems receive overlapping chemical information, but receptor sensitivity and neural processing can vary.
According to researchers analysing the many types of coriander, there are hundreds of different volatile compounds, with the group of compounds formed by aldehydes standing out as significant. In 2024, researchers analysing 40 varieties of coriander reported that 207 different compounds were identified, with aldehydes dominating in producing unique odours such as citrusy, soapy, oily, and floral.
The chemistry of various cilantro cultivars also influences the aroma. Differences in the chemistry and cultivation of different varieties of cilantro help explain why one herb can seem citrusy and fresh to one person while making another person think of a more aggressive, soap-like scent.
Frequent encounters can affect your taste and attitude towards a particular item, but no system yet exists that could completely override a genetically determined response. Taste is the outcome of a combination of biology and personal experiences, which means that a person who starts with negative feelings towards cilantro could tolerate it without actually losing taste perception.
It is crucial to bear in mind that cilantro has varying tastes because our sensory systems perceive the same chemical mix differently. Thus, when someone calls the herb “soapy,” they are referring to a perception.
The evidence points to an interaction between chemistry, receptors and experience:
Cilantro contains aldehydes that contribute strongly to its aroma.
OR6A2 is associated with sensitivity to aldehydes and cilantro’s soapy perception.
Retronasal smell carries food aromas from the mouth to the olfactory system.
Taste and smell are integrated by the brain into flavour.
Genetics can influence sensory sensitivity, but preference is not determined by one gene.
Together, these factors explain why cilantro can be bright, citrusy and herbal for one diner but pungent or soapy for another. The disagreement is sensory, not imaginary.
The flavour of cilantro is a prime example of how taste involves factors apart from the tongue. Its distinctive aromas arise from volatile aldehydes, and the strength of the herb’s soap-like taste may depend on olfactory receptors like OR6A2. The smell is perceived retronasally in addition to the taste and other oral sensations, to produce flavour. Genetics can explain these differences, but experience and other sensory factors are important as well.
Genetics affect whether someone perceives cilantro as soapy, but it alone doesn’t determine how much one enjoys the flavour of cilantro.
