The Science Behind Why Durians Smell So Bad

The durian season is at its peak, spreading airborne pungence in a neighbourhood near you. Haters have been spending the past few weeks scrunching up their faces in disgust after catching whiffs of this unbearable fetor of sweaty socks. Whether you are head over heels or against the mighty king of fruits, we can all agree that durians do get pretty foul smelling. In fact, their stench has been likened to “pig shit garnished with a gym sock”, and is said to make your breath smell “as if you just french kissed your dead grandmother”.

Durians stink so much that German postal workers turned nauseous and needed medical help after receiving just four durians via mail earlier this year. Not only was the building evacuated, six ambulances, five first-responder cars, two emergency vehicles and three different fire departments were also activated. Talk about drama.

Who needs the fire alarm when you have a handful of these? (Source)

A year ago in 2019, an Australian university had to be evacuated after staff mistook the smell of durians for a gas leak. The offending fruit also delayed an Indonesian plane for an hour after passengers refused to fly due to the stench, despite precautionary efforts to mask the smell with pandan leaves and coffee powder.

With all the hate surrounding durians, it comes as no surprise that many Asian hotels and even our Singapore public transport system ban the fruit.

Why do durians smell so bad?

In short, it is caused by a specific, rare amino acid.

A panel of trained smellers (yes, there are professional sniffers) helped researchers narrow down the dizzying smell to two chemicals, ethyl (2S)-2-methylbutanoate and 1-(ethylsulfanyl)ethanethiol. The former smells fruity, while the latter smells like onions. When combined, however, these two chemicals were indistinguishable from the durian odour. 

The science behind the malodour lies in a rare amino acid called ethionine. As the tropical ball of spikes ripens over time, its ethionine level increases, and a plant-specific enzyme releases an odorant from ethionine, causing the trademark stink to waft through the air.

You can just smell it. (Source)

Knowing how much ethionine is in a durian is actually useful as overconsumption may lead to health risks. In an experiment, rats subject to high doses of the amino acid developed liver damage and liver cancer. Thankfully, you will need to eat a lot of durians for that to happen. A 70kg human being will need to binge eat eight times his body weight worth of durians in a day to reach a significant enough level of toxicity. That being said, eating eight times your body weight of anything would probably kill you.

Low concentrations of ethionine may, instead, have positive immunomodulatory effects. Durians are actually superfruits too. 

If durians are scientifically smelly, why do some find them fragrant?

The rare amino acid is not all that durians have. This revolting fruit also contains 44 active aromatic compounds. While some of these contribute to the scents of skunks, rotten eggs, rotten cabbages and onions, others contribute to the smell of sweet caramel, honey, and fruity scents. One of the aromatic compounds identified even smells like soup seasoning.

As such, depending on an individual’s own sensitivities to the sweet-smelling and stinky compounds, everyone will have a slightly different impression of a durian’s smell.

What if I touch the durian flesh by accident, how do I get rid of the smell?

A popular folk remedy involves filling a few empty durian shells with water, and then scraping your fingers along the grooves in the shell before washing your fingers in water.

Recent research even suggests that this may be more than just a mere myth, and that some chemicals in the shells can indeed neutralise the funky smell. Another popular and effective folk remedy is to use a clean durian seed like a soap under tap water. The trick is to use a clean seed with minimal leftover durian flesh, and to really scrub your palms and fingertips.

Durian shells – they stink, but get you smelling fresh. (Source)

I heard that you will die if you drink alcohol while eating durians. Is that true?

This is a common belief in Southeast Asia, and is not one without merits.

A Japanese university found that the high sulfur content in durians inhibits the activity of an enzyme responsible for metabolising alcohol in the liver. This causes a temporary 70% reduction of the body’s ability to clear toxins, including alcohol, from the body.

Yes, alcohols are toxins. They kill cells like microorganisms, which is why we use it to preserve food and sterilise needles.

Furthermore, overripe durians will start to ferment and become slightly alcoholic themselves. As you can imagine, eating durians and drinking alcohol will be a double whammy to your health.

When will this smelly durian season end?

Durian haters will need to continue pinching their noses in repulsion until the end of August, at least.

The durian season is actually divided into three phases. The first phase is known as the early harvest phase, which runs from around May to June. Phase two begins in mid-June, and will go on until August. In Phase three, while the durians will still be harvested, they are likely to be of lower quality since they have been hanging on the trees for an extended period of time. Interestingly, mao shan wang durians tend to fall from the trees first, whereas D24 ones drop a little later.

One man’s meat is another’s poison. With over 30 different durian varieties to try, perhaps haters can one day find something that suits their flavour profile. 


Meanwhile, please excuse me as I grab a couple of durians from the uncle yelling lelong lelong.


Author

Vanessa Ng

Contributor

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