Cut onions toxic?

cookie8May 21, 2009

So, some ladies were talking and saying that once onions are cut, after sitting out for a bit, or in the fridge become quite toxic. Has anyone else heard of this? They say most food poisonings from potato salad happen because of the cut onions and not the mayo or other creamy ingredients. I say the mayo makers may have started this one!

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And commercial mayo has so many stabilizers and antioxidants and preservatives in it. it's pretty well shelf stable at room temp, provided it doesn't become contaminated. As a matter of fact commercial mayo prevents more food poisioning than it causes.
Onions toxic? No more than apples or carrots.
Linda c

Here is a link that might be useful: Food safety and mayo

    Bookmark   May 21, 2009 at 8:06PM
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Because of its ground contact, an onion could harbor bacteria spores (such as Clostridium botulinum) that could transfer from the outside of the skin to the inside flesh if the onion wasn't washed before being chopped. I think leeks are even more prone to bacteria than onions... This can happen with other foods from ground contact, such as cantaloupe and watermelon. Even using windfall apples picked up from the ground aren't supposed to be used for making home canned apple filling because of the potential for bacteria from contact with the ground.

People often don't wash melons before cutting, and often serve it at room temperature (or warmer), especially at picinics. The knife cutting through the outside of the fruit will transfer bacteria from the outside to the inside. Given the right conditions, those spores could rapidly grow into a toxin. The optimum conditions for growth of, and toxin formation by C. botulinum, include high moisture, low salt, low acid (pH greater than 4.6), low oxygen, and room temperature stored foods.

Clostridium perfringes is associated from ingestion of vegetative cells that produce spores and release toxins when in the intestinal tract. C. perfringens is present throughout the environment including soil, human and animal intestines, and in sewage. Growth can occur with or without oxygen. Heat-resistant spores are found in raw foods. This organism is also called the "cafeteria germ" because it commonly occurs in food produced in large quantities or food that has been left on a "too cool" buffet, steam table, or at room temperature too long.


    Bookmark   May 21, 2009 at 8:18PM
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Ok, Tricia posted a reality check on peanut allergies on the "banned food" thread. So I took her lead and googled botulism. According to the CDC:

Average US cases reported a year: 110
Percentage of which are food-bourne: 25%
Percentage of botulism cases that are fatal: 8%

Taking a straight average 2.2 Americans a year are going to die from food-bourne botulism. The highest percentage of US food-bourne botulism cases are in Alaska from fermented fish heads, etc. Since I don't live there or eat those things, my chances are even lower.

So while I'll still heed related food-safety protocol - and will always be leary of home canned goods and garlic oil - suddenly my fear of botulism is about on par with a freak accident resulting from a falling acorn.

Am I wrong?

Here is a link that might be useful: CDC

    Bookmark   May 21, 2009 at 9:36PM
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Well....perhaps if you left that onion in a closed enviornment for several days, any bacteria that weren't washed off MIGHT grow and produce spoors that might produce toxins, unless, of course you had salted it or dashed it with vinegar, IF it contained spoors of botulism.
But an onion does not become "toxic" when cut.
The issue with the melons etc is simply a matter of not washing the fruit, and since melons rest on the ground and are rarely cooked and have a skin which is rough and holds bacteria unless scrubbed they could easily be dirty.
I know that some bacteria produce toxins which make us ill, but to say that a cut onion becomes "toxic" after a few days is akin to my grandmother thinking that fish and milk consumed in the same meal become toxic.

    Bookmark   May 21, 2009 at 10:07PM
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Wait a minute! Grainlady, are you saying that onions should be washed? I've never, ever done that. I just peel them.


    Bookmark   May 21, 2009 at 11:35PM
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I never washed Onions either but I will start now, because it is very easy to do.
I've sliced Onions for years, put them in a Zip Lock and
in the frigedood , for later.
I'm still here, have to try harder.
All this talk about toxins, poisons, etc.
If you don't believe it , don't do it !!!

Advice is being given about everything.
We are lucky to have all this info available.
I take everything with a Grain of Salt.

Like the old saying
" Damned if you do and Damned if you don't " or something like that.
or something like that.

I'm getting delirious, must have eaten something bad.
Later, Lou

    Bookmark   May 22, 2009 at 1:08AM
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It sounds very hoaxy - they did get the information by e-mail. I wash my canteloupes, watermelon, pretty much everything. The only things I don't wash are onions, garlic, bananas. I guess I can expand to include everything. This is what stemmed the conversation - sorry, it's long...
(What they note can really be anything - ie onions at vendor - can't that also be the mustard everyone is putting their hands all over also? - best part ha ha, I totally called a mayo company on this one)

"Not sure how true but interesting.
I have used an onion which has been left in the fridge, and sometimes I don't use a whole one at one time, so save the other half for later. Now with this info, I have changed my mind....will buy smaller onions in the future...
Written by Zola Gorgon - author of several cookbooks.. Watch out for those spoiled onions...
I had the wonderful privilege of touring Mullins Food Products, makers of mayonnaise. Mullins is huge, and is
owned by 11 brothers and sisters in the Mullins family. My
friend, Jeanne, is the CEO.
Questions about food poisoning came up, and I wanted to share what I learned from a chemist. The guy who gave us our tour is named Ed. He's one of the brothers. Ed is a chemistry expert and is involved in developing most of the sauce formula. He's even developed sauce formula for McDonald's.
Keep in mind that Ed is a food chemistry whiz. During the
tour, someone asked if we really needed to worry about
mayonnaise. People are always worried that mayonnaise will
spoil. Ed's answer will surprise you.
Ed said that all commercially-made Mayo is completel safe.
> "It doesn't even have to be refrigerated. No harm in refrigerating it, but it's not really necessary." He explained that the pH in mayonnaise is set at a point that bacteria could not survive in that environment. He then talked about the quint essential picnic, with the bowl of potato salad sitting on the table and how everyone blames the mayonnaise when someone gets sick.
> Ed says that when food poisoning is reported, the first
thing the officials look for is when the 'victim' last ate ONIONS and where those onions came from (in the potato salad?). Ed says it's not the mayonnaise (as long as it's not homemade Mayo) that spoils in the outdoors.
> It's probably the onions, and if not the onions, it's the POTATOES. He explained, onions are a huge magnet for bacteria, especially uncooked onions.

You should never plan to keep a portion of a sliced onion. He says it's not even safe if you put it in a zip-lock bag and put it in your refrigerator. It's already contaminated enough just by being cut open and out for a bit, that it can be a danger to you (and doubly watch out for those onions you put in your hotdogs at the baseball park!)
> Ed says if you take the leftover onion and cook it like crazy you'll probably be okay, but if you slice that leftover onion and put on your sandwich, you're asking for trouble. Both the onions and the moist potato in a potato salad, will attract and grow bacteria faster than any commercial mayonnaise will even begin to break down.
> So, how's that for news? Take it for what you will. I (the author) am going to be very careful about my onions from now on.. For some reason, I see a lot of credibility
> coming from a chemist and a company, that produces millions of pounds of mayonnaise every year.'
> Also, dogs should never eat onions. Their stomachs cannot metabolise onions.

    Bookmark   May 22, 2009 at 9:18AM
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That is very interesting. I've never washed an onion after peeling it and I always have part of a cut onion in the fridge. Never thought a thing about it!

    Bookmark   May 22, 2009 at 10:01AM
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Well like many here I've never washed an onion and I'm not about to start. BUT I also never save a cut onion. Even if I only use half. And, not because I worry about bacteria. I throw it out strictly because of flavour quality. I learned a long time ago that a cut onion refrigerated for a day or two,regardless how it is wrapped does not retain the texture or the flavour of a fresh sliced/cut onion.

    Bookmark   May 22, 2009 at 10:33AM
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For eating raw I'd agree, yellow much more so than red. But for chopping up and sauteing and then adding a half dozen more ingredients? I know my palate would never know the difference so for me throwing the remains out would be wasteful.

    Bookmark   May 22, 2009 at 10:46AM
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that email is really a hoax....because of the high sulfur content, onions are an antibacterial agent. Nothing is a "magnet" for bacteria although it was an old wives tale (similar to eating fish and milk in the same meal) that cut onions would absorb the bacteria in the air and render the passing of disease less likely. Some "old timers" would leave a plate of sliced onions out in the house when someone was ill so the germs would go to the onion and not make others sick. And my great grandmother made an onion poultice to clear up a chest cold. And we also know that eating raw onion reduces cholesterol and reduces blood clotting, and some believe that onions and garlic eaten raw will cure a cold.
Onions contain a powerful antioxidant.
However, I do know that onions or potatoes or carrots that have been grown in soil contaminated with fecal bacteria have the potential for carrying the bacteria on the skin and if not proplerly washed, the inside of the vegetable could become contaminated with ecoli and the bacteria could grow and make you sick.
So....peel your onions and wash your potatoes....but potatoes boiled for salad would not carry ecoli.
Most likely the food at a picnic that made yous ick was the fried chicken, the undercooked burger ior the coconut cream pie.
Neither onions nor cut potatoes can "become a magnet" for bacteria. If that were so, the public healths ervice would mandate piles of cut onions and potatoes in public places rather than recommending hand washing.
Linda C

Here is a link that might be useful: medicinal onion

    Bookmark   May 22, 2009 at 11:11AM
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Life is toxic! None of us are getting out of this thing alive! If people have to dredge up little things like this so they can have something to worry about, have it pretty good if all you can find is a lethal dose of onions! Jeesh.

When you leave the house also look for that piano that is falling out of the 2nd story window and that open manhole cover on the way to the car.


    Bookmark   May 22, 2009 at 11:48AM
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I agree, Ann, I've never washed an onion and I don't intend to start. Sheesh. I peel the darned things and my knives are clean. I do wash produce like melons and apples or grapes that I get from the grocery store because I don't know who the heck has handled them.

I never keep cut onions in the refrigerator for another day because, as Ann pointed out, they deteriorate and lose their pungent qualities, which is why I use onions in the first place.

I have long said that commercial mayonnaise is so full of preservatives that it would probably last forever, now it seems that food experts agree with me. I'm not going to leave a bowl of potato salad in the 90 degree heat for several hours because that's just asking for trouble, but I'm not going to worry about that same bowl sitting on my dining room table for half an hour. I worry more about the eggs in the potato salad far more than the mayo, the onions or the potatoes.

As for the toxic onion thing, I think it's a load of horse hooey. As LindaC pointed out, onions are actually an antibacterial and no food substance, to my knowledge has been found to be a "magnet for bacteria".

Those ladies that got the email? I'm sure they sent it to my mother, along with the nonsense about children going blind from sunscreen and the poisonous spider waiting to bite your butt in the bathroom at the airport. She forwards all those things to me, and I keep telling her to check snopes before she believes those things.

Foodonastump, the chances of botulism are miniscule, I know. But since I can hundreds of jars of homegrown vegetables, I'm extremely careful because it's one of the problematic products and I like to choose my risks carefully.

Truthfully, you are a lot more likely to get botulism from commercially prepared food than you are from home cooked stuff, like those people who drank the Bolthouse Farms carrot juice after it was not properly refrigerated or the people who ate the restaurant baked potatoes which had been wrapped in foil and left on a counter for several hours.

The 8% that die are a minority, of course, but the ones who don't die are left with severe health problems that are sometimes life long, and I don't want to deal with that either.

I know kframe had some family friends who were hospitalized for months and have singificant disabilities due to botulism poisoning, so it does happen. It just doesn't happen very often. If you aren't a home canner and don't own or run a commercial food business, it's probably not much of an issue.


    Bookmark   May 22, 2009 at 2:35PM
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I look for those things every day but there are no manhole covers here and
no Piano's in the trees.

I'll have to find something else to worry about ???

But I will peel the onions and wash them.
Same as Potatoes but I'll wash them first, then peel.

If I use half an Onion, I wrap the other half in Plastic Wrap,
put it in a Zip Lock and in the frige.

I've used them 2 to 3 days later for Spaghetti Sauce ,
Stuffing, etc. Even Steak sandwiches.

And you all know, how everyone loves my Sauce ( Gravy ) and
Stuffin .

I don't have that luxury, to throw good food away.
I have a little common sense left, to know ,
when everyone is so up tight about Germs that,
they have to wear gloves to go shopping and
carry bottles of hand sanitizer, etc.

And then can't do a simple thing like washing a Potatoe or Onion that has been in P**P,
or better yet, don't know it's origin. ???????????

Here is the Onion I found in my remote bin. Think it was posted on WFD.
Have to check that bin at least once a year !!!!!

I couldn't even throw that away. It was put into a pot,
Peeled it first !!!
If it takes, I'll put it in the ground, with the flowers.

One time I put an Onion in a Container and labeled it.
Put it in the Frige.

I didn't put a date, so when I looked in after a few months
it had hair and eyes.

Really Mean looking !!! and I think it was trying to say,
" I'll get you , LOU "

So before it grew Arms and Legs, I burned it in a Bonfire.
I could hear some squeals as it burned.

Now I check every corner of the Frige and date Items,
because one time I found a Kid I didn't know I had.
He was 5 years old.

Didn't know how to talk yet but mumbled " Me Lou "
I said " Yeh Sure , Me Tarzan "
That's a true story from,
Lou, Heh ! Heh !

There are 64,000 stories in the big City.

    Bookmark   May 22, 2009 at 2:48PM
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Here's what has to say about the email...


Here is a link that might be useful: Toxic Onions

    Bookmark   May 22, 2009 at 4:44PM
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Does anyone wash Celery, that has Black Dirt in between the Stalks, or
Just chop it into whatever you are making.

Onions, Potatoes, Celery ?????
I think all these things grow in the ground.

I don't really give a Rat's Petutti, what anyone else does.
Just bringing up " Food For Thought"

I believe Everyone
- - - - - - - -

Speaking of Old Wise Tales:

When I was very young, ( I was at one time )
I had two Large Warts on my right thumb. Guess I was about 11 or 12 years Old.

My mother cut a Potatoe in half and rubbed it on the Warts,
then had to bury the Potatoe .

I wasn't to look where she buried it.
She said the Warts would go away. I said " Yeh ! Sure "

Then I forgot about it.
You know, I don't remember when the Warts Dissapeared ???
But they were gone!!!
Has anyone ever heard of this one?

    Bookmark   May 22, 2009 at 7:25PM
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Lou, I've heard of it, but it didn't work for the Plantar's Wart on the bottom of my foot, the doc had to cut that off. It was sore as heck too, I wish the potato would have worked.

I grow my own onions and potatoes and yes, I grow them soil amended with good old horse manure. I do wash them when I dig them, and before storing them, just as onions from the store get washed before packaging. However, after that gets washed off and the onions get stored, I just peel them. They've already been washed once when I buy them and any contaminants that they picked up through handling would be removed when I peel them. I see absolutely no reason to wash them again, whether they come from my garden or from the store.


    Bookmark   May 22, 2009 at 10:20PM
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Hallelujah !!!!! and Amen!

That one in the Photo is growing good, in the Pot. All the stems straightened out.

    Bookmark   May 23, 2009 at 12:32AM
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Oh jeepers. Yet another food that is going to kill me. I guess I should just slit my wrists right now so I can stop worrying about them.

Honestly, is there some wizened up paranoid schizo in a closet somewhere who spends all of his time dreaming up the next email warning to send out to us?

If cut onions were so dangerous, restaurants wouldn't cut them by the tub full to have ready for use, the health inspectors would see to that.

I have never washed an onion before cutting the ends off prior to peeling it and I'm not going to start now.

Thank you foodonastump for doing the research so I didn't have to! :D I'm going to take it a bit further and posit that the 2.2 people who die each year are very likely people who have other health problems or suppressed immune systems. People who could just have easily died by catching a cold.

Keeping to the basic kitchen rules our Moms and Grandmas taught us, things like washing cutting boards between uses, refrigerating/heating foods thoroughly, washing our hands etc., is common sense. Unless one is cooking for somebody who is quite ill or frail, that's all that is necessary.

    Bookmark   May 23, 2009 at 9:36AM
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I thought it was amusing how the e-mail chains are taken seriously. Unless it is on the news or have read it in the paper I am not really buying. Still, I do get paranoid where I get my food as to who touched it, how it was handled etc. Not crazy paranoid but enough not to just eat unwashed fruit or veggies. Ah, cannot wait until my garden starts producing! I grew potatoes just for their skins (see previous threads) - mmmmmm.

    Bookmark   May 23, 2009 at 10:05AM
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Your Thread just lit a light Bulb!!!

About 25 years ago, I was in a friends Steak Shop.

Maybe some of you know of the place.

Walt's Steaks in Clifton Hgts. , Pa. It was well known for miles around.

He would cut up Onions in small cubes for Sandwiches and Put them in Large Plastic Jars , to
Store them in the frige. and take out some as he needed them, on the Grille.

He did this since the mid 40's; after the WW2, until the
late 70's.

While watching him ,I said " Walt, why don't you put them in a large pot and steam them,
then put them into your Jars."

He started doing that. It was easier, because they were
already cooked.
All he had to do was Brown them a little on the Grille.

He said to me " Lou, after all these years, of doing the Onions my way,
you come in with something that simple "
" Why didn't you tell me before " ???

We would have been in real trouble, doing it that way now.

I know what you are saying about washing the Onions.
But you learn something every day.
Or else we would know what we know now.
They are getting Grants to study all these things.

It seems the same as me,you are being a little hard headed,
because you have done it this way,
Since the begining of time.

I always try to use a little Common Sense too.

And let a little Knowledge seep in.
I still cut an Onion and put it in the frige for later.

Tastes good to me!!!

PS: I don't want to argue with you, I'm getting paid to study Onions, not Debate.
I've wasted enough of the Taxpayers Money already!!!

    Bookmark   May 23, 2009 at 3:48PM
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I put cut onions in the fridge all the time, and I wasn't listed in the Obits today, so I guess I'll keep doing the same. Sometimes I keep them so long that they are dried out on the cut end. I just slice off the dried out part and use the rest. I toss them if they are slimy or have started growing a fur coat.

    Bookmark   May 23, 2009 at 9:38PM
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I have always washed my onions after peeling them. I would not use an unwashed onion but to each his own. If everything we did killed us, we would all have been dead a long time ago. I personally should have died from my New York City street hot dog and crepe obsession.

Good luck!

    Bookmark   May 24, 2009 at 7:55AM
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spedigrees z4VT

The funny thing about onions is that they, and garlic, are in fact both toxic to dogs. I find this curious in light of the fact that for people these vegetables are believed to be healthy (ie proven health benefits of Mediterranean diet) for people. Oddly too is that scientists found a case of onion toxicity in a rat, since the nutritional requirements of rats and men are nearly identical.

That is a good point about washing off cut onions before using them, esp if they are to be eaten raw, in a salad for instance. I confess I haven't always done this, but I think I may start now.

    Bookmark   May 24, 2009 at 9:22AM
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Chocolate is toxic to dogs too but not humans... Just sayin.

    Bookmark   May 24, 2009 at 12:50PM
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i received toxic cut onion again.

what's the conclusion ?

I do not think cut onion is toxic simplily b/c it is cut. it gets toxic just like everything else. as far as washing it, it's a good idea, just in case there is soil from the skin.

    Bookmark   March 14, 2011 at 7:16PM
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I have consumed onions , radishes,carrots, right from the soil. Knocked off the loose soil and munched away. Never getting sick. Don't forget about built up immunities. Back in the day when meat was Hung underground they would just carve off the green ,feed that to the pigs, and the next cut was for dinner.

    Bookmark   April 16, 2011 at 9:47PM
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I have consumed onions , radishes,carrots, right from the soil. Knocked off the loose soil and munched away. Never getting sick. Don't forget about built up immunities. Back in the day when meat was Hung underground they would just carve off the green ,feed that to the pigs, and the next cut was for dinner.

    Bookmark   April 17, 2011 at 1:32AM
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