Woolworths claims to have lowered the level of pyruvic acid in its new variety – thus removing a key tear trigger from the vegetable – and describe it as similar in sweetness to brown onions but significantly less pungent.

Ryan McMullen, Woolworths New Zealand’s general manager of fruit and veg, told the Herald the onion was “bred using natural and traditional means” and didn’t employ any genetic modification (GM) techniques.

Woolworths’ tearless onions are mainly grown in Pukekohe by Wilcox, a major player in New Zealand’s fresh produce industry.

While you can nab your average brown onion at Woolworths for $1.69 per kg, the tearless variety will set you back 77.5% more with their $3 per kg price tag.

Where did Woolworths find a natural variety?

Woolworths’ tearless onions originated from a breeding programme by seed company Nunhems, which is owned by German conglomerate BASF.

“Tearless onions took over three decades of investment, development, careful selection and hard work to develop,” McMullen said.

“It began in the 1980s when the first two onions were cross-bred using natural methods.

“As technology advanced, volatile onions were identified using gas chromatography, which allowed breeders to identify the onions that would cause fewer tears when cut.”

The US was the first country to approve Nunhems’ variety for use, introducing them to the market in 2017 as “Sunions”.

Sunions began selling in Canada soon after their launch in the US, and they made their way to Spain in 2020, Italy in 2021, and the UK, France and Germany in 2022.

Woolworths, selling Nunhems’ variety under the Happy Chop brand, brought tearless onions to consumers across the Tasman in 2023.

Elvira Dommisse once worked as a scientist at the New Zealand Institute for Crop & Food Research (now Plant & Food Research), where she set up a GM onion programme at Crop & Food’s Lincoln facility.

She told the Herald the variety “would have been developed by selective breeding, possibly with the aid of some non-GE molecular techniques, like marker-assisted breeding”.

Tearless onions aren’t new, right?

While the naturally crossbred variety will be new to Kiwi shoppers, the world’s first tearless onions were developed in Canterbury by a group of New Zealand and Japanese agricultural researchers in 2007.

Scientists who worked with Dommisse at Crop & Food used gene-silencing techniques for their research.

Gene silencing works to effectively “turn off” a gene – in the tearless onions case, the one responsible for the enzyme that makes you cry when slicing onions.

However, a separate GM crop had disappointing results when it was taken from the lab to undergo field tests, and, by 2012, Crop & Food’s onion project was abandoned.

Dommisse said the field-trialled onions were designed to be resistant to Roundup, but they “performed poorly in the field and were susceptible to plant diseases”.

A 2008 report on the programme’s results said initial findings on the tearless onions had still received considerable attention from overseas biotech companies and were helping to aid alternative approaches.

Tom Rose is an Auckland-based journalist who covers breaking news, specialising in lifestyle, entertainment and travel. He joined the Herald in 2023.