Has your durian been artificially ripened?

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SINGAPORE - A video warning people about artificially ripened durians has been circulating on social media and stoking fears about the safety of durians from Malaysia that are sold locally.

While it has been reported in Thailand and Vietnam that some durian farmers and traders use artificial ripeners, the Singapore Food Agency (SFA) says it has "not detected any non-compliances on the use of chemical ripeners in durians during our tests".

According to its website, SFA "samples and tests for pesticide residues and chemical ripeners that are known to leave trace levels of residues on treat(ed) fruits".

Fruit, including durians, that fail these safety tests are not allowed to be sold in Singapore.

Artificial fruit ripening with suitable ripening agents, such as ethephon, is an "acceptable practice", says SFA. This may be used after harvesting to "control the rate of ripening".

Calcium carbide, however, is prohibited as a fruit ripener in many developing countries because of the greater safety risks it poses to workers who come into direct contact with it, the agency adds.

Food science experts tell The Straits Times that both ethephon and calcium carbide can be carcinogenic. Over-ingesting the latter may also lead to headaches and dizziness.

But Associate Professor Liu Shao Quan from the National University of Singapore (NUS) believes that consuming durians treated with these chemicals should not pose any adverse health effects.

"Assuming that the ripening agents are not in direct contact with the fruit, it is the gases released from the agents that accelerate fruit ripening, and evidence has shown that these gases are released at low levels," says Prof Liu, who is from NUS' Food Science and Technology department.

Agreeing, Professor William Chen, director of Nanyang Technological University's Food Science & Technology programme, says "the risk of getting adverse health effects should be low" as people do not eat durian husks, though safety issues may arise if agents are in direct contact with the fruit.

If people open the durian fruit themselves, he recommends that they wash their hands before eating to be safe.

When asked, Mr Kelvin Tan, manager of durian stall 99 Old Trees in Owen Road, says he has "never come across" artificially ripened durians in his five years or so in the trade.

A durian seller from Ah Ma Food Stall in Tanjong Pagar, who wants to be known only as Mr Xiong, says while he is unsure if he has ever received artificially ripened durians from suppliers, he makes sure to check the quality of the durians before selling them.

Both sellers import their durians from Malaysia.

Mr Tan believes there is no reason to use artificial ripeners.

"Artificially ripened durians do not taste as good (as naturally ripened ones). Word spreads fast within the durian industry and the traders' reputation will be affected," he says.

As to whether carbide is used on Malaysian durians, American durian enthusiast Lindsay Gasik, 32, believes that use of artificial ripeners is not common in Malaysia.

Ms Gasik has been travelling for durians since 2012 and documents her experiences on a blog called "Year of the Durian".

She visits countries such as Malaysia, Thailand and Indonesia every year, staying for about two to three months each time during durian season.

On her travels, she has "never seen any kind of ripening agent used in Malaysia". Durians there are generally allowed to fully ripen before they are harvested, she adds.

However, she has seen durian farmers in Thailand using ripening agents like "ethephon mixed with turmeric powder".

She has also seen carbide being used on durians in Bali and Sumatra in Indonesia, though the use of ripening agents in Indonesia is less common than in Thailand.

Ultimately, Prof Chen says not using any ripening agent would be ideal as "anything of synthetic nature would not be good for our health".

"Let nature take its own course."

 

Thorny issues

How can one check whether a durian is artificially or naturally ripened? American durian blogger Lindsay Gasik offers some clues.

 

1. It is not durian season in Malaysia

Durian seasons in Malaysia typically span late May to August, and mid-November to February.

If you are buying a durian during off-season, you may be buying the fruit from Thailand or Indonesia, which is more likely to be treated with artificial ripening agents.

 

2. There is yellow powder or paint on the stem

This is the turmeric powder mixed with ethephon. Turmeric powder is used to mark which durians have been treated with ethephon and also acts as an anti-fungal while the durians are ripening.

 

3. The durian stem is old and withered, yet the flesh is still firm or does not seem overripe

Cut-harvested durian has flesh that is hard and crunchy. The flesh may take up to nine days to become soft and similar to the texture of Malaysian tree-ripened durian. During that time, the stem will dehydrate and oxidise.

 

4. The stem is sliced off

This is to hide either the yellow paint or the old withering stem.

 

5. It tastes like a cut-harvested durian

What the cut-harvested durian tastes like depends on how many days you wait for it to become soft. If you wait until the texture of the cut-harvested durian is soft like that of Malaysian tree-ripened durians, the cut-harvested durian will normally be more watery, intensely sweet, more sulphurous and often has a slight acidity like berries or pineapple.

 

Source: The Straits Times © Singapore Press Holdings Limited. Reproduced with permission.

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