| Cilantro, Mimics and Memes |
“Ew! Smells like soap!”
That was the response from gardeners back in the 1960s and 1970s when offered a sample of fresh coriander to try. Noses turned up, they quickly moved on to the geraniums, petunias, and tomatoes on display in the greenhouses at Richters. In those days, herbs amounted to three things: mint, parsley, and an illegal herb that some hippies smoked. Everything else was a spice on the spice rack, brought in from faraway places, and that’s where coriander was situated in the gastronomic landscape – as a spice for baking, pickling, sausages, and seasonings.
The people who grew coriander those days wanted it only for seeds, not the leaf. Life was good since the seeds we got from Europe were of the type that produced a nice crop of seeds and not much leaf. Coriander was simply coriander; there were no named varieties available at the time. It was just Coriandrum sativum to the botanists.
As herbs began to take off in popularity in the late 1980s, coriander suddenly became a schizophrenic conundrum for growers. People were waking up to the culinary virtues of fresh coriander leaf, or cilantro, as it became known in the popular lexicon. The plant was now two different herbs, leaf and seed, each with different personalities and different uses in the kitchen. Meanwhile we started to see nice large bunches of imported fresh cilantro showing up in the local food markets. They had long stems and beautiful dark green leaves about the same size as Italian parsley. Local growers couldn’t compete with the imported stuff, and were asking why their coriander zoomed straight to flower before they could get a decent harvest of leaves.
|Coriander bolting. Plants go to flower and set seeds quickly without producing much leaf.|
What was wrong? Was it the way they were growing it? Were they seeding too late or too early? Were field conditions too hot or were the plants getting too much sun? In those days we could not find much reliable production information, and most of what was available was focused on growing coriander seeds for the spice market.
One of our customers, a commercial fresh herb grower, heard a rumour that some Chinese farmers were growing a different type of coriander that didn’t bolt or go to flower so quickly. The seeds were smaller than usual, he said. We began to look around at ethnic food stores and it was true that there were different corianders with different seed sizes. So we decided to try some of these. In a quick and dirty trial in our greenhouses we planted pots with large seeds, small seeds, and seeds in between. Some seeds came from South Asian food markets in Toronto. Some came from Egypt and Turkey; others came from American sources. But all of the plants bolted just like our standard no-name variety from Europe. We were stumped.
Unknown to us at the time, German researchers were looking at hundreds of coriander strains collected around the world. Their work showed that certain varietal features are strongly correlated with whether or not a variety will be slow to bolt. The more leaves the variety has at the base of the stems, the more likely it will be a slow-bolting type. And varieties with many basal leaves also correlate with smaller seed size, so that small-seeded varieties are less likely to bolt compared to the large-seeded varieties. So the rumour of Chinese farmers growing a small-seeded, slow-bolting variety could well have been true.
But as our little greenhouse trial showed, there are exceptions, because all of the small-seeded varieties we tested bolted quickly, just like the large seeded ones. Looking back we cannot rule out the possibility that high summer heat during our trial may have pushed even slow-bolting varieties to bolt early. We know from research that environmental factors, particularly high heat, can trigger premature flowering and seed set.
By the 1990s, commercial slow bolting varieties started to hit the market in North America, varieties such as ‘Long Standing’, ‘Slo-Bolt’, ‘Santo’, and ‘Leisure’. Our own field trial of these varieties, along with 16 landraces from Europe, Central Asia, North Africa, and the Far East, revealed that ‘Santo’ and ‘Leisure’ performed best in our test plots. So, it seemed, life was good again. We now had both types of coriander, the original spice type that produced lots of seeds, and the cilantro type that produced lots of leaves.
|Slow bolting corainder suited for fresh cilantro production.|
As interest in herbs grew, people wanted to grow their own in their kitchen windowsills to harvest year round. Indoor growing works reasonably well for the easier herbs like basil and mint – herbs that regrow after cutting – but cilantro is not one of them. Like other tap-rooted members of the parsley family, the Apiaceae, cilantro does not respond well to human grazing, and the only way to produce a continuous supply of fresh leaves indoors is to reseed repeatedly to replace cut-back plants as they are discarded. That proposition was simply too taxing for would be kitchen growers, and many dropped the idea of indoor herbs altogether. Like a demanding diva, cilantro ruined the show for everybody.
From all the questions we were getting, it was clear to us already by the 1980s that finding a cilantro that thrives indoors and tolerates repeated haircuts would be a really big deal.
Introducing Rau Răm
“It’s not the same!” she exclaimed. “You can’t use it like coriander!”
My friend Yen and I were visiting a local green grocer in Toronto’s bustling Chinatown on Spadina Avenue. Yen, at the time, owned a Vietnamese delicatessen in the area that served eat-on-the-go food Vietnamese style to shoppers looking for a quick bite. I told her that we had added the Vietnamese herb called rau răm to the next Richters catalog and we called it Vietnamese coriander. She insisted that the taste was all different. She said that no Vietnamese would ever use rau răm in place of cilantro.
Traditionally, rau răm is used in very specific ways, for hôt vịt lôn made with fertilized duck eggs and for various raw salads collectively called gỏi. It is not used for much else according to Vietnamese people I have talked to. From Yen’s reaction, it was pretty clear that my appreciation of fine coriander was about as nuanced as a prohibitionist’s appreciation of fine wine.
|Rau răm or Vietnamese coriander.|
“Well, maybe it is not exactly the same,” I said, plaintively, “but it’s close enough, at least for North Americans, isn’t it?” She would have none of that, and gave it to me in no uncertain terms: “No! No! No!” But even as she delivered that stern evaluation, it came with a barely concealed giggle that she and her assistant, who had joined us from Yen’s store, shared at my expense.
This was a giant bucket of cold water on my idea. We already had a nice crop of plants growing in the greenhouses. It was super easy to grow, tolerant of repeated cutting, and definitely had strong aroma and flavour. How could this not be the perfect mimic of cilantro, I thought. Disconsolate, and searching for something – anything – to grab on to, I meekly asked, “Why the giggles? What was funny?”
With a mirthful smile and tone, she said rau răm suppresses sexual desire in men. I don’t remember the exact words she used, but oriental modesty would have demanded some sort of indirect way of being very direct. It might have taken me more than a few seconds to digest this surprising turn, but I am sure that the way she put it was almost as if rau răm was a woman’s secret joke on men, shared among the sisterhood to be used when needed. Or maybe I was just set off-balance enough in that moment to think the worst.
We went ahead with our plan to introduce this Vietnamese coriander to gardeners in 1985. Then known botanically as Polygonum odoratum (and now as Persicaria odorata), it became a bestseller as people wanted it for both outdoors and indoors. The aroma and flavour were different but not different enough, and soon the herb took its place in the pantheon of must-have herbs. And it is still selling strong more than 30 years later. I suppose that if there were any remorse about doing a disservice to my fellow menfolk by launching a covert male anaphrodisiac on the unsuspecting, I can persuade myself that, in the battle to control men’s sexual urges, men soon had Viagra to help. That’s the thought that I take comfort in anyway.
But this idea that rau răm suppresses male sexual desire stuck like a burr on my back. What if there is something to it? I have long touted the power of traditional knowledge and how we cannot glibly dismiss it. I believe that knowledge handed down from generation to generation usually has a nub of truth behind it – enough to justify the effort to learn and master the knowledge and pass it on to the next generation – even if science has not yet provided a rational basis.
On the possible libido-altering effects of rau răm, the literature is not very forthcoming. Wikipedia has something about Buddhist monks growing and using the herb to control their urges, but when I checked the source cited to back up that claim, the cited online article no longer mentions anything about monks. Wikipedia also offers the aphorism, “Rau răm, giá sống,” which supposedly works as a juxtaposition of the libido-suppressing rau răm next to libido-boosting bean sprouts giá sống. I asked Vietnamese friends if they knew this saying but none did. In the scientific literature, all references to libido effects seem to point back to a book published in Saigon in 1954 by a French botanist, Paul Alfred Pételot. From what I can tell, this is the first scientifically documented link between Buddhist monks and rau răm.
In the popular Vietnamese literature one can find articles that mention the use of rau răm by Dominican monks, not Buddhist monks. If true, this use could go back as far as the 1600s when the first missionaries arrived in Vietnam. If I could read Vietnamese I would like to dig deeper to find out how far back modern Vietnamese accounts of this story can be traced and whether they predate the information in Pételot’s book. Oddly enough, for all of its association with preventing sex, rau răm is a symbol of wanton male love in Vietnamese culture, and there is an aphorism about it:
Rau răm, difficult to grow in hard soil, easy to uproot,
No matter how much in love, he will be someone else’s husband.
What this is saying is that men, symbolized by rau răm, are difficult to keep in hard conditions and are quick to leave. So whether or not they are in love, despite how much love is showered on them, they can leave for another woman. These two lines in Vietnamese have a sing-song cadence, and according to a Vietnamese friend, the saying has been shared among women as a warning about the nature of men. In Vietnamese poetry, women are portrayed as flowers, symbols of beauty and fragility, while the rampant rau răm with its nondescript flowers is an apt symbol of men. Since men can be despicable, I have to wonder if there is another aphorism somewhere that tells women to add rau răm to a man’s dinner to keep him in line.
So what about that soap smell? Is coriander really that bad? John Gerard, the 16th century English herbalist and botanist, certainly thought so. In his famous compendium, The Herball, or, Generall historie of plantes, he called coriander “a very stinking herbe, smelling like the stinking worme called in Latine Cimex.” While it is not clear what this “stinking worme” was, since Cimex today refers to bed bugs and they don’t have a larvae stage, his scathing assessment clearly did little to recommend fresh leaves for English kitchens. Meanwhile, the seeds fared better, for he also wrote that the “pleasant and well savouring seed is warme, and very convenient to sundry purposes.”
Gerard’s “stinking herb” meme is not too different from how many people describe the fresh leaves of coriander today. Those who dislike cilantro compare it to “dish soap”, “paint”, “stink bugs”, “mouldy carpet”, “dirt”, “rancid body odour” or worse. There’s even a website devoted to disparaging cilantro, IHateCilantro.com, where thousands of members commiserate about their encounters with cilantro and share ways to fight back. Meanwhile at least one cilantro lover is fighting back at the haters in an expletive-filled blog with recipes and tips on irritating the haters. I must admit that I never imagined herbs could become so divisive, or political even. One cilantro hater tweeted, “I wish Donald Trump chose to hate cilantro instead of Muslims and Mexicans.” Well, now we know this is serious!
Scientists have been looking at why people have such sharp opinions on cilantro. It is not just a droll fascination with a silly debate; it is actually trying to get to the core of an important part of the puzzle of how we perceive odour and flavour. Most people know that the tastebuds in our mouth help us to discern tastes such as sweet, salty, savory, and bitter. These tastebuds are loaded with receptors that bind specific chemicals found in our foods. When, say, a sugar molecule nears a sweet receptor, it binds to the receptor, setting off a signal that gets sent to the brain indicating that something sweet is in the mouth. In a similar fashion, there are receptors in the nose that bind to specific chemicals we breathe in, and those receptors also send signals to the brain. It so happens that there are receptors that are known to bind to key molecules in cilantro. That’s how we use our sense of smell and sense of taste to detect cilantro.
|Olfactory system. Receptors in the nose bind volatile chemicals emitted by fresh cilantro leaves thus sending a "smell" signal to the brain. Similar receptors in the mouth bind chemicals send the "taste" signal to the brain.|
Research has shown that there is an important genetic component that affects how we perceive cilantro. Lilli Mauer, a graduate student at the University of Toronto, looked at how people of six different ethnic backgrounds perceive cilantro, and discovered that Caucasians and East Asians disliked cilantro significantly more than South Asians and other groups surveyed. And although the sample size was small, she found that the ethnic group that most liked cilantro was Hispanics. It so happens that humans are endowed with taste and smell receptors that come in different models and these function slightly differently, and which model we have is controlled genetically.
What Mauer was able to show was that the presence of one or another model correlated strongly with the frequency at which people liked or disliked cilantro. Her work showed for the first time that perception of cilantro is strongly affected by our genes. But, she points out, our genetic differences do not explain completely our reactions to cilantro because other factors appear to play a role as well. She gave the example that, in cultures accustomed to using a lot of cilantro, the intensity of the signal to the brain could be altered over time, even in individuals who have the genes to dislike cilantro.
Close on the heels of Mauer’s work, a study was published by the American personal genomics company, 23andme, in which the genome data of over 14,000 customers was compared to customer perception of, and preference for, cilantro. Customers wanting to know about their genetics can send in a sample of their spit and the company will analyze their DNA. Customers answer a lot of detailed questions, including whether cilantro tastes like soap and whether they like the taste. In the study the results were broken down by sex and by ethnic group. Compared to men, women were significantly more likely to find cilantro to be soapy and more likely to dislike it. Among the seven ethnic groups looked at, Ashkenazi Jews, followed closely by South and North Europeans, were most likely to find the taste to be soapy, at a frequency of about 1 in 7 or 1 in 8. African-Americans, Latinos, and East Asians were less likely to find it soapy, about 1 in 11 or 1 in 12, and South Asians were the least likely, at a rate of only 1 in 26.
The study found that those who found cilantro to be soapy had sections of DNA that were closely linked to a specific receptor called OR6A2. This receptor is known to bind to fatty aldehydes, a group of compounds commonly found in cilantro and in soap. These compounds are volatile meaning that they can easily escape to the air at room temperature and enter the nose. A handful of these fatty aldehydes are important components of the essential oil from cilantro leaves, often accounting for more than 40% of the oil[*], and are often described as “waxy” or “soapy”, as well as “citrusy”, “floral”, “meaty” or “herbal”. With this connection to OR6A2, we now have a genetic smoking gun, and a target for further investigation.
About the same time the 23andme study was published, there was another study that looked at identical and fraternal twins and how they reacted to cilantro. The study was important because it looked at the role of genetics in a more precise way. Identical twins share 100% of their DNA while fraternal twins share only 50%. It stands to reason that identical twins should be more likely to agree on their perceptions of cilantro than fraternal twins. Indeed, the results showed exactly that.
The picture emerging is getting clearer. We are learning how our genetics affect our perceptions, not just of cilantro, but of everything we experience. Poor John Gerard, the 16th century English herbalist, didn’t know it at the time but he must have been the one out of eight Englishmen condemned by his genes to perceive cilantro as soap. If the IhateCilantro.com website had existed in his time, no doubt he would have joined it and added his “stinking worme” pronouncement to the website’s long list of disparaging comments about the taste submitted by members.
With all this talk about oils and aldehydes and such, you might ask how do Vietnamese coriander and true coriander stack up against each other? If Vietnamese coriander, or rau răm, is a good mimic of true coriander, then does it have any of the fatty aldehydes found in cilantro? In fact it does. It has decanal and dodecanal, two important cilantro aldehydes, and at much higher concentrations, with these two making up more than half of the leaf oil. Dodecanal in particular can rise up to 60%, a level never seen in true cilantro oil. Dodecanal is described as having a “soapy”, “waxy”, “citrusy”, and “floral” scent. So the soap element is definitely more pronounced. This could be part of the reason why Vietnamese cooks do not consider rau răm to be a true substitute for true cilantro. However, for the rest of us with a less refined appreciation of fine coriander, the high decanal content may be a compensating factor. This aldehyde, known for its “sweet”, “waxy”, “orange peel” and “floral” notes, has the kind of organoleptic profile that the flavour industry actually likes and uses in food products. But of course, for Vietnamese cooks, there is that unsexy libido-repressing meme about rau răm that seems to get in the way...
The Vietnamese have the Chinese to thank for bringing another coriander mimic to Vietnam, a plant called culantro. It has many regional and local names, none of which seemed to take hold in the English literature, so at Richters we decided to use Mexican coriander. Botanists know it as Eryngium foetidum. Its origin is believed to be a pan-Atlantic region encompassing tropical Africa, tropical America, and especially the Caribbean Islands. The Chinese are believed to have introduced it to Southeast Asia in the 1880s as a substitute for fresh coriander. Adopted like a native son in Vietnam, the herb was christened ngò gai and is commonly offered alongside true coriander in markets.
Although it belongs to the same botanical family (the Apiaceae) as true coriander, it is a very different beast in many ways. In the tropics the biennial is found growing in shaded wet areas near cultivated fields. Sometimes known as thorny coriander or spiny coriander, it can actually be quite prickly, with small yellow spines forming at the leaf margins. Under the hot sun during the long days of summer, it tends to bolt, producing flowers that are even more prickly than the leaves. Yet despite its sharp differences in morphology, its scent and flavour are similar to true coriander, only more intense. Its essential oil is very high in those aromatic fatty aldehydes that we have been discussing, and among them, (E)-2-dodecenal is by far the most important. As much as two thirds of the extracted leaf oil consists of this one aldehyde.
|Culantro or Mexican coriander.|
This fatty aldehyde has a really low odour detection threshold value, which means that our noses can detect it better than most other aldehydes. So the combination of this aldehyde’s high concentration and low odour detection value helps to explain culantro’s incredibly strong aroma. This is just my own speculation, but I think the relative absence of other aldehydes in the mix makes its odour “cleaner” than true coriander. Perhaps it is this intense, clean aroma that induced the Chinese to bring this plant to Southeast Asia. There had to be something amazing about it, otherwise why would they bother when they already had cilantro?
Okay, after all this beating around the bush, I am sure you are wondering where I stand on the cilantro lover-hater divide. Without a doubt, I am with the lovers. But not too much rau răm please.
* It should be pointed out that the steam distillation methods used to extract essential oils from plants can alter oil composition and do not necessarily reflect the true natural composition of oils in the fresh leaves. There are recent indications that changes in oil composition do happen when coriander leaf oil is extracted. Drawing conclusions based on extracted essential oils is therefore a hazardous practice and any conclusions based on them should be taken with a grain of salt. Still, the overall importance of fatty aldehydes in coriander and its mimics is well established.
1. Pételot, P. A. 1954. Les plantes médicinales du Cambodge, du Laos et du Vietnam. III. Archives des recherches agronomiques au Cambodge, au Laos et au Viêtnam, ne 22: 23.
2. Mauer, L. & El-Sohemy, A. 2012. Prevalence of cilantro (Coriandrum sativum) disliking among different ethnocultural groups. Flavour 1:8. Retrieved from http://www.flavourjournal.com/content/pdf/2044-7248-1-8.pdf.
3. Mauer, L. 2011. Genetic determinants of cilantro preference. (Master’s thesis). Retrieved from https://tspace.library.utoronto.ca/bitstream/1807/31335/1/Mauer_Lilli_K_201108_Msc_Thesis.pdf.
4. Eriksson, N., Wu, S., Do, C. B., Kiefer, A.K., Tung, J.Y., Mountain, J.L., Hinds, D.A. & Francke, U. 2012. A genetic variant near olfactory receptor genes influences cilantro preference. Flavour 1:22. Retrieved from http://www.flavourjournal.com/content/pdf/2044-7248-1-22.pdf.
5. Knaapila A., Hwang, L.-D., Lysenko, A., Duke, F. F., Fesi, B., Khoshnevisan, A., James, R. S., Wysocki, C. J., Rhyu, M., Tordoff, M. G., Bachmanov, A. A., Mura, E., Nagai, H., & Reed, D. R. 2012. Genetic analysis of chemosensory traits in human twins. Chem. Senses 37: 869.