A wit once noted that while an onion can make you cry, no vegetable can make you laugh. Scientists in New Zealand have peeled both notions into the dustbin.
Banishing a bane of cooks since the Bronze Age, they have developed a tearless onion by switching off the gene behind the enzyme that makes us cry at the chopping board. The tearless onion appears just like the ordinary garden variety vegetable but has been engineered not to disturb the lachrymal glands of the eye, which secrete tears.
“It has all the sweet smells of an onion, but without the take-your-nose-away kind of smell,” Colin Eady, a scientist at the New Zealand research institute Crop & Food, said.
Not only do they have up to 500 times less of the irritant but the process is also said to improve milder onions, which do not induce tears but lack the flavour of a regular onion. Dr Eady said that this was achieved through the prevention of sulphur compounds being converted into the tearing agent and redirecting them into compounds responsible for flavour and health.
“They are mild because they don’t have as many of the sulphur compounds we associate with the flavour and health properties of an onion. They are so much reduced that you could say the onions are like bags of water. We anticipate that the health and flavour profiles will be enhanced by what we’ve done.”
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Previously it was thought that the tear-producing agent was produced spontaneously by cutting onions. But the layers began to be removed by researchers from House Foods, the Japanese manufacturer that isolated the onion “blubber” gene in 2002.
The New Zealand scientists, using “gene-silencing” technology from Australia, have since developed the ability to insert DNA into onions that switches off the eye-watering gene. The achievement, still in the early stages of development, roused the agricultural industry when it was unveiled at a symposium on allium species — onion, garlic and shallots — in the Netherlands.
The international trade journal Onion World devoted a cover story to the tearless onion. It quoted Michael Harvey, a horticultural professor at the University of Wisconsin, as saying that the onions will become the fare of kitchen tables around the world.
Dr Eady said that tissues should remain within arm’s reach for at least a decade as the development process continued. “I’m more interested in sustainable production and the onions we are working on must be capable of being grown in an efficient manner,” he said.
“We have a burgeoning population to feed and, with climate change and other challenges, available resources are being reduced. The gene-silencing system can also be used to combat virus diseases, and biotechnology in general can help us produce more robust crops.” When they do sprout, the onions may be as good as money trees.