Scientific American Instant Egghead

科學人雜誌速成科學家

Start chopping a pungent onion

切開一顆洋蔥

and before too long you're bound to tear up.

不久你就熱淚盈眶了

How exactly does this bulbous veggie have the power to make us cry?

到底是甚麼原因讓這鱗莖植物擁有讓人流淚的魔力?

The second you slice into an onion you change its chemistry.

刀子切下去的那一剎那，洋蔥的化學性質就跟著改變了

Cutting an onion ruptures its cell walls.

切開的動作破壞洋蔥壁細胞

You can think of these walls as sturdy balloons

你可以把這些壁細胞想像成堅固的氣球

that hold in a cells contents.

裡面裝滿了化學物質

When a knife breaks through, [pop]

當刀子切下去的時候

swarms of molecules and enzymes escape.

大量的化學分子和酵素釋出

Some of those enzymes break down sulfur compounds present in the onion

其中一些酵素切斷洋蔥裡的硫化物

generating sulfenic acids in the process.

並在過程中釋放出次磺酸

Other chemical reactions convert sulfenic acids

其他的化學反應將次磺酸

into a volatile and irritating gas called onion lachrymatory factor.

轉化成活性大且刺鼻的氣體，洋蔥催淚物質

When this gas wafts into your eyes,

當這氣體飄浮到你的眼睛

certain neurons instruct your tear ducts to flush out this potentially harmful substance.

特定的神經元會下達指令到淚腺，以沖出潛在的傷害物質。

Fortunately, there are a few tricks you can use to keep the waterworks to a minimum.

幸好, 我們還有幾個減少流眼淚的小技巧

Storing the onion in the fridge or freezer for at least 30 minutes before chopping,

切洋蔥前先放把洋蔥放入冷藏或冷凍庫, 至少要30分鐘

slows down its enzymes which should help prevent tears.

降低酵素的活性，防止淚腺受刺激分泌淚水

Briefly boiling an onion should have the same effect.

川燙洋蔥有有相同的效果

High heat can deactivate enzymes.

高溫使酵素失去活性

Another strategy is cutting the onion under running water

另一個方式是在流動的水中切洋蔥

to prevent the gas from reaching your eyes.

避免催淚氣體傳播至眼睛

But the easiest solution is probably a pair of ski goggles or sunglasses.

不過戴上一副滑雪眼鏡或太陽眼鏡該是最方便的

Hmm

嗯

[chop, chop]

[我切，我切]

Umm, if goggles or glasses don't work out so well, don't worry.

如果滑雪眼鏡或眼鏡效果不大，不用擔心

Scientists are trying to tackle the problem too.

科學家也正在想辦法解決這個問題

Researchers in Japan and New Zealand have collaborated to create a tear free onion.

日本和紐西蘭的研究人員

They silenced one of the genes that makes onion lachrymatory factor, the volatile gas that irritates your eyes.

合作研發"不哭"洋蔥

But don't look for it on the shelf, this genetically modified product is not currently on the market.

將洋蔥中產生揮發性氣體的基因關閉

Other researchers used traditional plant breeding to create the "Ever Mild", a yellow onion with really low levels of the volatile gas.

揮發性氣體也就是讓眼睛不舒服的催淚物質

You can find it in some grocery stores.

不過現在還買不到，這種基因改造洋蔥還沒上市

But until these products are more widely available, we'll probably have to stick with Kleenex and sunglasses.

其他研究人員則是利用傳統種植法

For Scientific American's Instant Egghead, I'm Ferris Jabr.

培育出含較低揮發氣體的黃色洋蔥："Ever Mild"

[music]

在某些超市可以找到