Naked Science Forum
General Science => General Science => Topic started by: chris on 26/10/2002 18:01:29
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Japanese scientists have taken a step closer to making an onion that doesn't make you cry by unravelling the biochemical processes behind the lacrimatory (tear-causing) effects of the onion family.
The explanation put forward by the Naked Scientists research time in response to a question sent in by a listener (26th May 2002 show - see archives) was that cutting up onions releases enzymes called allinases which break down amino acid sulpoxides - the substances which give the onion family their distinctive smell. The product of this degradtion - sulphenic acid then turns into something called syn-propanthial-S-oxide which irritates nerve fibres on the surface of the eye, triggering tear production. - Or so thinking went at the time. This meant that if scientists wanted to genetically modify onions to produce a version that wouldn't make you cry, they would have to tamper directly with the substances that give onions their flavour, which would defeat the object. Indeed, onions bred to be tear-free, like the Veri Sweet vegetable recently marketed in Washington State, have a characteristically different taste
But, Japanese scientists have found that the eye-burning effects of an onion are actually down to a single enzyme - lachrymatory-factor synthase - which generates syn-propanthial-S-oxide. Because this seems to be the unique function of this enzyme, and it is not involved in flavouring the onion, removing it from the plant could result in an onion that tastes great, but doesn't sting your eyes!
So there you have it - the appliance of science ![:D]
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Hi Chris!
I was wondering if you could perhapz give me a hand. This topic really interests me! I'm in the biotech challenge that'll be held province wide in canada shortly and i've decided that i would research and submit a report on this topic. However, i haven't found sufficient info yet. And inorder for me to be able to extract the enzyme, and genetically engineer a tearless onion, which i plan on doing, i'm gonna need a lot more info. I tried contacting S imai(head incharge of this experiment in japan), unfortunately i was unsuccessful. So, i was wondering if you could send me some info on this, other than what i already know; something new, perhapz on how i would go about extracting it. Thank you for your understandin' and cooperation!
Sincerely,
Jazmin
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Hi Jazmin
wow, what an ambitious project ! Since this made Nature, are you sure what you are planning is feasible within a reasonable time frame ?!
I'm not a protein biochemist, so I can't really help with details about extraction of the protein, but the details of the identification are in the materials and methods section of the nature paper (reference below) which you could photocopy or purchase online. I'm surprised that they didn;t get back to you when you wrote. Most people respond to me when I drop them a line.
I'd be very interested to hear more about your project and your work in general - please drop me a line back here or to :
chris@thenakedscientists.com
Best wishes and my apologies not to be able to offer more constructive assistance
Chris
References :
http://www.nature.com/nsu/021014/021014-10.html
http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v419/n6908/abs/419685a_fs.html&dynoptions=doi1036537757
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on a lighter note, i discovered on a recent snowboard trip that if you wear your snowboard goggles whilst cutting and cooking the onions... your eyes are kept trouble free, and you look pretty cool.
Thats Economics...
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Tried your ridiculous suggestion and couldn't see anything owing to tinting...I also looked stupid.
Conclusion : That's rubbish.
I also tried cutting the onions underwater, but I couldn't hold my breath for long enough.
Conclusion : That's near-drowning.
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you couldn't see anything through the tinting of your board goggles, the problem was that you used a high light level lense, these are often darker or even silver reflective such as the Oakley Iridium. What you need to use is a Low Light level lense which allows you to see more detail... i suggest a nice pair of Dragons like mine. [8D]
Thats Economics...
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You know people, if you just have your kids cut the onions you won't have any problems at all. duh!
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I love onions. Not eating them, but in fact love them. The life of an onion is dear to me. When I cut one up, it makes me cry with sadness. However, no one belives me. They just think it's the onion effect.
I've heard that you can cut an onion under cold running water to help. I also know that you can rub your hands on stainless steel to rid the smell on your hands.
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as i've suggested to other people, the best way to not cry is to wear snowboard goggles.
Resident Tour Operator - The Naked Scientists
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quote:
Originally posted by Ians Daddy
I love onions. Not eating them, but in fact love them. The life of an onion is dear to me.
Ronnie,
In what aspect do you love onions? Why is the life of an onion dear to you?
Angel (https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fsmilies.networkessence.net%2Fs%2Fcontrib%2Fruinkai%2FbiggrinangelA.gif&hash=7a3ab31861328a98db23edcb21639ab9)
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I just love onions. I've adopted several, but they always go bad and I have to ask them to move out.
Sorry, I'm starting to sound like our friend Garry. I'm just being silly.
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I heard two things to prevent the crying. The first is to light a candle while chopping the onion, and the other is to hold a piece of bread in your mouth. Myself, I have just learned to do it so fast that it doens't have time to get to my eyes. I think chopping an onion with a piece of bread in your mouth would look pretty silly. The candle -- well, I don't know. You just might look a little metaphysical.
Bezoar
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Ok, it's solved... Light a candle, run some water, wear some goggles and eat some bread. Cutting up an onion has never been so easy and rewarding all at the same time.
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And play new age music -- something has to explain that weird scene.
Bezoar
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Hahahaha....no doubt.
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The REAL way to stop onions stinging your eyes - keep them in the fridge overnight before you use them, or - cut them in half, run the insides with water, cut in quarters, do the same, cut again do the same, the more times you run it under water before using it the less it will sting your eyes. I don't see how holding bread in your mouth, running water or lighting a candle will stop the onions stinging your eyes, perhaps can you explain it to me? I can see that snowboard goggles will certainly work - however, not everyone snowboards and consequently not everyone owns snowboard goggles.
Am I dead? Am I alive? I'm both!
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I'm not sure I'll feel like I'm cooking good New Orleans cuisine without crying when I cut the onions. It's like taking the smell out of the garlic. Can't imagine that tearless onions would taste the same, and even if they do, I'll bet a whole crew of people out there will swear that they don't. Too many years of conditioning. I may have to leave that to the next generation. Please excuse me. Have to go find my goggles now.
Bezoar
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Snow goggles in New Orleans? You're just plain silly. That's just crazy talk[:D]
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Ronnie,
I thought you liked crazy talk from women[;)]
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Not for skiing -- for cooking, silly!
Bezoar
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I do, I do! Any talk from women is good / crazy.
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I heard that if you put a lemon in your mouth when cutting onions then it stops you crying (dont know what to think about that)
my username is a nickname i had cince i was 9 (i am 14 now but dont take the mickey of me cause i am younger than you)
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Wearing contacts can also inhibit the enzyme's ability to affect all the nerves of your eye. I switched from glasses to contacts a few months ago and it's been great! I can eat all the onions I want!
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When I want to chop or cut onions for a meal then I put them in my fridge
for about one or two hours beforehand so that the amino juices don't
seep out and then I don't cry.
Also I wear glasses and they don't stop the onions making me cry if I have to help others
This is not a scientific practice but just from many years of cooking for
myself.