What’s that smell?

This is going to be a bit of a smelly blog, but don’t feel offended. Some of the smelly foods are natural, others are manmade. Some of the foods make you smell. But be aware that smell is a very individual experience. Something that would be revolting to one person could be a delicatessen to another. Each to their own senses. If you read to the end you will find a surprising fact about strong tasting foods.

The spiky durian

The terrible smell of durians (Photo: Wikimedi)

The terrible smell of durians (Photo: Wikimedi)

First out is the durian, a fruit native to Brunei, Indonesia and Malaysia, although now grown in several other countries with Thailand the major exporter. If you see something looking like a hedgehog (or echidna if you’re Australian), that is the durian. Its edible flesh has a strong and distinctive odour even with the skin intact. Some people regard the durian as pleasantly fragrant and the flesh is praised in Southeast Asia for its nutty, custardy taste.  However, others find the aroma overpowering and revolting and  describe it  as rotten onions, turpentine, raw sewage, or gym socks.  Because of the smell it is actually illegal to carry this exotic fruit on public transport in Singapore. Like many stinky foods, people often love it or hate it.  Connoisseurs say that durian is worth the stench and that bad breath can be overcome by using freshening mints or toothpaste after consumption.

The strong odour of the durian can be detected from far away by animals.  Squirrels, mouse deer, pigs, orang-utans, elephants, and even carnivorous tigers eat the fruit and as a result dispose the seeds in the surrounding environment to the benefit of the plant. Thiols or mercaptans are compounds which give faeces, rotting flesh and the spraying of skunks their awful smells. They were earlier believed to also be responsible for the smell of durians, however, new findings pinpoint a complex mix of up to 50 different chemicals.

In case you want to try a durian be aware that it inhibits the liver enzyme aldehyde dehydrogenase important in the detoxification of alcohol. This might account for stories that getting intoxicated while eating durians can lead to death.

Ancient garlic making its mark

Nothing surprising here. Garlic is widely used around the world for its pungent flavour as a seasoning or condiment. It has been used as both food and medicine in many cultures for thousands of years, dating at least as far back as when the Giza pyramids were built. Garlic is still grown in Egypt, but the Syrian variety is the kind most valued now. The garlic bulb is the most commonly used part of the plant. Garlic bulbs are normally divided into numerous fleshy sections called cloves. Garlic cloves are used for consumption (raw or cooked) or for medicinal purposes. The pungent, spicy flavour mellows and sweetens considerably with cooking.

Garlic is known for causing bad breath, as well as causing sweat to have a pungent ‘garlicky’ smell. This is caused by allyl methyl sulphide. It is a volatile liquid that travels with the blood to the lungs and further to the mouth, causing bad breath, and to the skin, where it is exuded through skin pores. Washing with soap is only a partial solution in that most of the smell stays. The bad breath might be neutralised by drinking milk at the same time as consuming garlic. Plain water, mushrooms and basil may also reduce the bad breath but are not as effective as milk.

Where is the smell coming from?

Smelly urine - it is the asparagus (Photo: Mundoo)

Smelly urine – it is the asparagus (Photo: Mundoo)

Asparagus has been used as a vegetable and medicine, owing to its delicate flavour and diuretic properties. The finest texture and the strongest and yet most delicate taste is in the tips. The effect of eating asparagus on the eater’s urine has long been observed and described as a filthy and disagreeable smell. There is debate about whether only some people produce the odour since not everyone can smell it. It was originally thought this was because some of the population digested asparagus differently from others, so some people excreted odorous urine after eating asparagus, and others did not.

However, it has now been proven through genetic testing that most people produce the odorous compounds after eating asparagus, but only about 22% of the population have the genes required to smell the ammonia and various sulfur-containing degradation products.

You can test yourself if you belong to the exclusive one fifth of the population. Just sniff away.

Inulin is found naturally mostly in root vegetables. It is a soluble fibre, one of three types of dietary fiber including soluble, insoluble, and resistant starch.Tiny amounts are found in onions and garlic, while much larger amounts are found in starchy roots such as chicory root and Jerusalem artichokes. Inulin is indigestible by the human enzymes ptyalin and amylase, which are adapted to digest starch. As a result, inulin passes through much of the digestive system intact. It is only in the colon that bacteria metabolise inulin, with the release of significant quantities of carbon dioxide, hydrogen, and methane. This will result in flatulence, exacerbated if you belong to about 30–40% of the population in Central Europe suffering from fructose malabsorption since inulin is a fructan.

To avoid embarrassment it might be wise to consume inulin-containing foods in moderation.

Disgusting varieties of fermented fish

Surströmming is a foul smelling fish (Photo: Stefan Leijon)

Surströmming is a foul smelling fish (Photo: Stefan Leijon)

There seems to be as many varieties of fermented fish as there are fishing nations in the world, and several of them have a disgusting stench.

Indigenous to northern Sweden, surströmming is herring that is fermented in barrels for a couple of months, then put into tin cans for up to another year. The fermentation is so strong that the can actually bulges from pressure, and it has been banned by some airlines who say that it is an explosive safety hazard. It is best enjoyed in the outdoors because of the strong odours released when the can is opened, often compared to rotten eggs, vinegar, and rancid butter.

Hákarl is fermented shark meat and is an Icelandic delicacy. It tastes like ammonia and causes humans to gag when they put it in their mouth. Sharks get rid of their urine by changing it into urea and passing it through the skin. When a shark dies, the urea in its body turns into ammonia and this is what give hákarl its unique taste. I am assured that it tastes better than it smells, as long as you can keep it down.

A similar Korean speciality is hongeo hoe, or hongeo sashimi, rotten raw skate fish that equal to the shark bathe in its urine to give the flesh a smell of ammonia. Hongeo fans rave about its unique flavour, but it is an acquired taste that is usually masked by mixing it with other foods or drink, like makkeolli – a kind of Korean rice wine. The smell in hongeo specialty restaurant can stick to your clothes and be with you for some time.

Finally the kusaya, a Japanese fish that is soaked in salted fish juice, then dried in the sun. It doesn’t sound like a problem until you’re told that the same brine is used again and again and again. The best kusaya is supposed to come from brine that has been in continuous use for many years. The brine is never refrigerated and could have been fermenting in a container for centuries. Translated, the name indicates what you experience close up, kusaya means ‘that stinks’.

Efforts to make cheese stink

Stinky cheese is not for everyone (Photo: Andrew Eick)

Stinky cheese is not for everyone (Photo: Andrew Eick)

There seems to be a bit of a competition in making the absolute stinkiest cheese. The Vieux-Boulogne was named the world’s stinkiest cheese by a team of researchers at Cranfield University in 2004 using an electronic nose and 19 human testers. Thus it should be an objective test. It out-stank a number of close competitors, including the Epoisses de Bourgogne, Napoleon’s favourite that is now banned from all French public transport, and the Limburger, the previous owner of the stinky crown. As a matter of fact, one of the bacteria that creates human body odour, Brevibacterium linens, is that same bacteria used to ferment the Limburger. As a result, when people say Limburger smells like dirty human feet they are scientifically correct. So disappointment in the German camp, at least they had tried hard.

The British seemed equally disappointed. They thought their Stinking Bishop, officially Britain’s smelliest cheese, should have got the dubious honour. It’s one of the oldest types of cheese in the world, dating back to the time of the Cictercian monks. It’s washed with pear juice, which makes the rind orange and really sticky. The smell is only in the rind, not in the actual cheese.

And the Italians voted for the Casu Marzu, or “rotten cheese,” a Sardinian sheep’s-milk cheese whose secret ingredient is thousands of writhing maggots hidden beneath the rind.

But despite the stink, some people still eat them all with enjoyment.

And other stinky foods

Stinky tofu or chòu dòufu is a form of fermented tofu that has a strong odour. It’s a popular dish at night markets in China, Taiwan and Southeast Asia. Fresh tofu is added to a brine made from fermented milk, meat, vegetables and sometimes seafood. The brine fermentation can take as long as several months. The brine can be so rotten that it will be infested with maggots – even people who like it often admit its smell resembles rotten trash or faeces. It’s usually served deep fried, often drizzled in sauce and topped with sour pickled vegetables.

Kombucha is a form of tea that gets its special punch from yeast, which is allowed to ferment in the warm beverage for a month. The result is a drink that has long, green strands of gunk floating in it, and that smells like compost. There are wild health claims associated with drinking kombucha but no scientific evidence that the drink can help liver function, immunity or anti-cancer activity. However,  what is clear is that this beverage can cause upset stomachs, infections and bad breath.

Nattō is a traditional Japanese food made from soybeans fermented with Bacillus subtilis. It has a very slimy consistency, looking quite off-putting, and a raw fermented smell, but is not as pungent as stinky tofu. Nattō may be an acquired taste because of its powerful smell, strong flavor, and slimy texture. However, this one might actually be good for you being a rich source of proteins and vitamin K2. The perceived flavour of nattō can differ greatly between people. Some find it strong and cheesy and they use it in small amounts to flavour rice or noodles. Others find the taste bland and unremarkable, requiring the addition of flavoring condiments such as mustard and soy sauce.

Century egg or pídàn is a Chinese dish made by preserving duck, chicken or quail eggs in a mixture of clay, ash, salt, quicklime, and rice hulls for several weeks to several months, depending on the method of processing. Through the process, the yolk becomes a dark green to grey colour, with a creamy consistency and an odour of sulphur and ammonia, while the white becomes a dark brown, translucent jelly with little flavour.

So what is all that leading to? Well, science has the answer.

The benefit of strong aromas

Bite size related to taste intensity (Photo: horizontal integration)

Bite size related to taste intensity (Photo: horizontal integration)

We take bigger bites of foods we are familiar with and smaller bites of those that require more chewing. Scientists have shown that small bites are a good thing since they actually make your stomach feel fuller faster, reducing the amount of food eaten and thus calorie intake.

Now it has been found that people take smaller bites of food when it’s accompanied by stronger aromas. Scientists designed an interesting eating contraption to separate smell from other factors that affect how big of a bite participants take. They found that when food was associated with strong aromas people took smaller bites.

It probably doesn’t matter if the the aroma is pleasant or unpleasant, it is the strength that counts. When a strong smell is presented to the nose, eating is paired back to reduce the amount of flavour experienced. Combining aroma control with portion control could fool the body into thinking it was full with a smaller amount of food, aiding weight loss.

Maybe the stinky cheese is not that bad after all.

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