A Singapore Subway Sign (Photo by Julien Mouille)

A Singapore Subway Sign (Photo by Julien Mouille)

10/26/2007

Accounting for Taste

by Vijay Venkatraman

In Singapore, the pasar melam – the roadside market – comes alive well after sunset. Tiny lights strung up on make-shift store fronts give the outdoor shopping scene a festive air. Lychees, mangosteens, rambutans and other tropical fruit hang tantalizingly in the fruit stalls, but one formidable-looking fruit holds it its own against the competition in the summer. It is durian season, and in South East Asia durian is king.

Cradling the spiky fruit in her palms, a patron examines the probables while her family looks on eagerly. Once she picks the winner, the little group withdraws into the darkness of the nearby alley. An assistant takes a machete to the durian and serves them the innards. The family doesn’t take leftovers from this clandestine feast. Well, there is very little left, but, more importantly, the “King of Fruits” is not allowed on subways.  Does their beloved durian have an image problem or what?

Fortunately, arranging a durian-tasting session in broad daylight in Boston is a cinch. There is no penalty for lugging one on the transit. Despite its obscurity, the football-sized fruit is available in the local Super88 and Chinatown groceries. Durians sit patiently in the produce section, waiting for connoisseurs or unwary foodies to walk down their aisle. Opting for the pre-packaged chunks of frozen durian seems unadventurous, but it is impossible to hack into the fruit with an average kitchen knife.

The Scent of the Durian

Admittedly, frozen fruit can only hint at possibilities, but sometimes that can be a good thing.  We cracked open the plastic box. Immediately, an odor reminiscent of high school labs with the Kipp’s apparatus bubbling away in the corner hit us. Here was fruit which, to our unsophisticated noses, smelled like rotting garbage. Unlike the mysterious ban on chewing gum, the Singapore authorities have a cut-and-dried case for keeping the durian out of confined spaces.  

Any fruit contains a variety of volatile organic compounds like esters, alcohols, aldehydes and ketones which give it a distinct smell, explains Dr. Rajarathnam Dharmarajan, senior chemistry lecturer at the National University of Singapore. He attributes the durian’s peculiar odor to a cocktail of sulphur-containing organic compounds – thio alcohols, thio esters and disulfides. Much the same compounds are present in the Allium species (onion family), meats, and some dairy products, but onion-like overtones are a rarity in fruits. Butyl ethyl sulfide, unreported in any other foodstuff, is present in the durian.  

The Psychology of Taste

The flesh of the durian tastes like exotic custard. Even for the uninitiated, the gustatory pleasure of the fruit could offset the olfactory impact . “Humans are genetically programmed to like sweet foods and dislike bitter foods,” says Dr. Marcia Pelchat, a physiological psychologist at the Monell Chemical Senses Center. But when it comes to aromas, we are molded only by experience, she adds.

Our responses to smells are primarily learnt, either culturally or through direct experience. The smell of the durian has emotional significance for natives of South East Asia, who have gorged on the fruit in the company of family and friends, Dr. Pelchat points out. They are not genetically inclined to disregard the smell – they have learned to love it. Neuroimaging studies indicate that it is possible for the rest of us to go from dislike to acceptance, once we get acquainted with this unfamiliar delicacy.

Decay-like odors do not seem to be innately offensive, says Prof. Paul Rozin, a cultural psychologist at the University of Pennsylvania in an email interview.  “Babies eat feces. We learn to avoid such odors, but then make many exceptions, like ripe cheese,” he points out. “We don't know how those exceptions come to occur, but most cultures eat some form of decayed food like cheese and wine.”

Designer Durian?

At the Horticultural Research Institute in Thailand, researcher Dr. Songpol Somsri is a man on a mission. This summer, after decades of crossing different varieties of the durian, he came up with a less-smelly hybrid. Further, by mapping the fruit's genome and zoning in on the odor-causing genes, Somsri plans to create smell-less durians for the commercial market. While this feature will make it easier for foodies worldwide to dig into the durian, the updated version may not be a hit with traditionalists.

“A big part of the incredible complexity and mysteriousness of durian is its smell,” points out Dr. Marty Fujita, an evolutionary ecologist in Ojai, CA. This durian-aficionado says that her mouth waters when she remembers the scent of ripe durians.  “Why mess with perfection?,” she asks simply.