Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: bezoar on 14/03/2004 14:50:32
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A thought just came to me as I was watching my grandson eat eggs for breakfast. I know that raw eggs can carry salmonella, but what about when you eat an egg sunny side up? Is the salmonella only in the white of the egg?
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Mmm...I eat egg sunny side up for a long time now and quiet often as well, you know they are just so nice they creaminess of the yolk and the springy, tenderness of the egg white and little bit of salt on the top when frying it (literately very small pinch ) and this is optional add a wee bit of soy sauce when eating it and....sorry OFF TOPIC
Back to the topic:
I think the salmonella is there naturally but the number of bacteria varies. Most of the time, after the egg has been cook the bacteria tends to be killed if not it's then killed in the stomach.
The bacteria might well be in the yolk
Tom
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If Salmonella has managed to get inside an egg, and mostly that's been Salmonella Enteritidis, it may find itself in various parts of the egg, between the membranes just under the shell, in the white, on or even in the yolk. The outer inners, such as the white (or albumen) are quite harsh environments and the bacteria are lucky to survive. If they reach the yolk though, which is highly nutritious, and if other conditions are right, they can start to grow rapidly.
If the egg is stored at refrigeration temperature, no growth should occur, as nearly all types of Salmonella cannot grow much below 10 degrees celsius. If eggs are stored at room temperature and the bacteria are on or in the yolk, they will grow. If such an egg is stored for some time, the bacteria can grow to very high levels, perhaps as high as 10 or 100 million cells.
If this is the case, the egg can be quite well cooked, and still some cells of Salmonella may survive. So, you might become ill even if an egg is quite well cooked, if it has been handled poorly before you cook it.
Some types of Salmonella can cause illness even when consumed in relatively low numbers, but the more you consume, the more likely it is you will become ill. So a fresh egg containing a very low level of Salmonella may make you ill, but this is much more likely if you consume an egg with a greater number of bacteria.
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Thanks Jules - nicely explained.
I have a follow-on question - how do the Salmonella spp. get into the egg in the first place ?
Chris
"I never forget a face, but in your case I'll make an exception"
- Groucho Marx
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Thanks Jules, but I have another question. I used to see these pictures of farm kitchens that showed eggs hanging in a wire basket in the kitchen, obviously not refrigerated. Then I read that eggs are covered with an oily substance (called the "bloom") when they come out of the chicken's oviduct, and if you don't wash the eggs, they'll stay fresh at room temperature for up to two weeks. So, that being the case, does staying fresh necessarily mean without salmonella? Does salmonella make the egg spoil? Or is there something in the bloom that inhibits the growth of salmonella?
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From what I've been taught, 99.9% of salmonella is on the shell of the egg not actually in the egg itself. Therefore you just have to worry about the small abounts that get transfered into the egg (most likeley into the white) when you carck it. Cooking the egg to any degree at all should kill any of this. Think about it. When you eat sunnyside up eggs the yolk is not cold is it? (unles you let it sit for a while of course.)
I know that eggs can sit out for quite sometime and still be good to eat. (obviously not as long as in the refridgerator). I've never heard anything about this "bloom", but it might make sense that it maybe blocks up any small pores in the shell and keeps air, bacteria, etc. out.
When 900 years you reach look as good you will not, hmm??
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So if the salmonella is on the shell, and you wash it well before you crack it, you could eat raw eggs?
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well eggs do have pores in their shells, and things can get through them. I think if you do completely disinfect the shell and are carefull while cracking you are reasonably safe, but you're still taking somewhat of a risk, especially if (as big J pointed out) the bacteris made it to the yolk. In thta case you might be in big trouble. Its all amatter of playing the odds game. How well do you do at casinos bezoar??
BOW DOWN TO THE LORD OF THE FLIES!!!!
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Is it really that likely there's salmonella in the egg ?? How weird ! How did it get there in the first place ? How do you guys like your eggs? I love oeufs à la coq, they're the best way to eat eggs :)
Am I dead? Am I alive? I'm both!
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I have some chickens that I get eggs from, and there is a "bloom" on the eggs, though I don't know how this interacts with salmonella. The eggs usually need to be washed because they get a bunch of chicken crap all over them, and I don't like to eat chicken crap with my bacon. I don't use soap when I wash them, but I do use an old toothbrush. Do you think this is enough to remove the bloom? Should I just use antibacterial soap when washing them instead?
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I think I might take this a one egg at a time...so let's look at the egg from the outside in, and the issue of bloom.
When the egg is produced, the outermost layer is the 'bloom' or a wax-like cuticle (to give the technical term). Broadly speaking it's like the waxy layer naturally present on some fruit, like capsicums (or peppers, as some will know them).
While in theory this covers the egg, in practice the chicken does not produce a perfect cuticle, so it may not be laid down over the entire surface of the egg. Also, when it's fresh, it's moist, but once the egg leaves the chicken and finds itself in a drying environment, the cuticle dries, shrinks and cracks.
So, in the real rather than the ideal world, while an egg does have a bloom (or cuticle) it frequently does not cover the entire egg and once the egg leaves the chicken, the cuticle breaks up over time.
More again soon...
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Finally, a chance to continue...
I thought I'd continue the egg story and along the way suggest answers to some of the questions raised by other participants in this topic, so...back to the BLOOM!
MooseHole mentioned 'extra protein' on the surface of eggs and washing to remove it, also mentioning the use of a toothbrush.
There is a debate in the commercial egg industry as to the relative merits of using what's referred to as wet versus dry cleaning - basically whether to use soapy water and sanitisers or abrasive dry cleaning with a brush.
Remember that the bloom on the surface of the egg is hardly ever complete or intact anyway, so removal of some if not all during cleaning may not necessarily be harmful. Leaving faecal matter (pooh!) on the surface, especially in larger amounts that stay moist for some time, may actually be worse. Why?
It's all about moisture. Going back to wet cleaning, the presence of moisture on the surface of the egg may ease the passage of microorganisms on the surface into the egg via the pores (more on pores later), while they remain stranded on a dry surface. This is particularly true if washing is not done properly. If washing is used, it's usually done as soon as possible after laying to minimise the time any residues (especially pooh) sit on the shell. The temperature of the egg at washing may well be in the low to mid 30s (degrees celsius) when washing happens. If the wash water is of lower temperature, the egg cools and a slight vacuum is produced, sucking water into the the egg, and perhaps bugs, like <I>Salmonella</I>, along with it. If eggs are washed, rinsed and sanitised, then each successive stage uses a higher temperature to avoid the vacuum effect.
So, if you do have some lumpy material on the surface of your eggs, it might be easiest and best to simpoly flick it off. If you want to remove smears of stains on the shell, then washing is OK, if it's done properly. I don't think the antibacterial soap is absolutely necessary )and this might lead to the transfer of taints/off-flavours to the egg), but hot water would probably do the trick.
Oh, while I'm here, for Quantumcat (a fellow Aussie - Hi!), I like my eggs lighly cooked, sunny-side up, topped with cracked black pepper, Tabasco sauce, and a generous sprinkling of freshly grated pecorino or pepato cheese...
Back soon.
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Finally, a chance to continue...
I thought I'd continue the egg story and along the way suggest answers to some of the questions raised by other participants in this topic, so...back to the BLOOM!
MooseHole mentioned 'extra protein' on the surface of eggs and washing to remove it, also mentioning the use of a toothbrush.
There is a debate in the commercial egg industry as to the relative merits of using what's referred to as wet versus dry cleaning - basically whether to use soapy water and sanitisers or abrasive dry cleaning with a brush.
Remember that the bloom on the surface of the egg is hardly ever complete or intact anyway, so removal of some if not all during cleaning may not necessarily be harmful. Leaving faecal matter (pooh!) on the surface, especially in larger amounts that stay moist for some time, may actually be worse. Why?
It's all about moisture. Going back to wet cleaning, the presence of moisture on the surface of the egg may ease the passage of microorganisms on the surface into the egg via the pores (more on pores later), while they remain stranded on a dry surface. This is particularly true if washing is not done properly. If washing is used, it's usually done as soon as possible after laying to minimise the time any residues (especially pooh) sit on the shell. The temperature of the egg at washing may well be in the low to mid 30s (degrees celsius) when washing happens. If the wash water is of lower temperature, the egg cools and a slight vacuum is produced, sucking water into the the egg, and perhaps bugs, like <I>Salmonella</I>, along with it. If eggs are washed, rinsed and sanitised, then each successive stage uses a higher temperature to avoid the vacuum effect.
So, if you do have some lumpy material on the surface of your eggs, it might be easiest and best to simpoly flick it off. If you want to remove smears of stains on the shell, then washing is OK, if it's done properly. I don't think the antibacterial soap is absolutely necessary )and this might lead to the transfer of taints/off-flavours to the egg), but hot water would probably do the trick.
Oh, while I'm here, for Quantumcat (a fellow Aussie - Hi!), I like my eggs lighly cooked, sunny-side up, topped with cracked black pepper, Tabasco sauce, and a generous sprinkling of freshly grated pecorino or pepato cheese...
Back soon.