The strange thing is that not everyone has this problem. While one leaf is enough to put me off, other people find coriander fresh and indispensable. How can exactly the same herb taste delicious to one person and like washing-up liquid to another? I asked Sissi de Beer, an applied physicist at the University of Twente. Her research includes studying how we can detect and recognise smells.
Why can coriander taste like soap?
"For a long time, this was a mystery," says Sissi. Researchers now know that our genes probably play a role. Genes are pieces of hereditary material that influence characteristics of our bodies, including how we perceive smells.
When you eat coriander, it releases aromatic compounds, including aldehydes. These are small molecules that can produce a particular smell. Some of the aldehydes in coriander smell soapy. Similar compounds can also be found in some soaps and cleaning products.
Your nose contains receptors that recognise these molecules. Think of them as tiny sensors, each sensitive to particular substances. One of these smell receptors is called OR6A2, which is sensitive to the aldehydes found in coriander. Research has found a link between genetic differences around these smell receptors and the likelihood of experiencing coriander as soapy. In other words, some noses seem to pick up that soapy smell more strongly than others.
Do people who think coriander tastes like soap have better genes?
As far as we know, no. Being more sensitive to the soapy smell of coriander doesn't mean you have better genes or a more highly developed sense of smell. It seems to be mainly about differences in the types of receptors in our noses and how sensitive these smell receptors are to particular compounds.
Whether these differences ever offered an evolutionary advantage, for example by helping people recognise food or potentially harmful substances, isn't clear. So my dislike of coriander may partly be in my genes. Personally, I think that's a perfectly good excuse.
Why do you taste coriander mainly with your nose?
I keep saying that coriander ‘tastes’ like soap, but according to Sissi, much of that experience actually happens in my nose. "As with many flavours, what we experience as taste is largely determined by smell." When you eat, aromatic compounds travel from your mouth to your nose. Your brain combines what you smell with what your tongue tastes. Together, you experience this as flavour.
You can try it yourself. Hold your nose tightly closed while eating coriander. According to Sissi, the soapy flavour should become much less noticeable. So two people can eat exactly the same coriander leaf and still experience it differently.
And coriander isn't the only example. Genetic differences also seem to influence how people experience the flavours of foods and drinks such as chicory, bacon and white wine.
Can I learn to like coriander?
Am I doomed to hate coriander forever? Fortunately, no. "You can get used to the taste," says Sissi. By eating coriander more often, you may eventually start to appreciate it. Think of Brussels sprouts, herring or feta: flavours you might have hated as a child but learnt to enjoy later.
My genes aren't going to change, of course. But perhaps my opinion of coriander will. Whether I'll start voluntarily adding extra coriander to my curry is another matter. For now, I'd rather keep the washing-up liquid next to the sink.
