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  4. Why are the yolks of hard-boiled eggs grey around the outside?
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Why are the yolks of hard-boiled eggs grey around the outside?

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Offline chris (OP)

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Why are the yolks of hard-boiled eggs grey around the outside?
« on: 23/08/2003 14:46:57 »
I have finally found that answer to the nature of the grey film around the yolk of a boiled egg...

"[high temperature when cooking an egg] causes a chemical reaction between the yolk and the white that leaves a green film around the yolk. That film is iron sulfide, caused by iron in the yolk reacting with hydrogen sulfide in the white"

So who wants to do the experiment in which a egg is hard boiled using a high temperature versus a cooler temperature ?

Chris


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« Last Edit: 11/01/2018 17:34:52 by chris »
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Offline bezoar

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Re: Why are the yolks of hard-boiled eggs grey around the outside?
« Reply #1 on: 23/08/2003 20:46:25 »
So that would explain why immersing the eggs in cold water afterwards sometimes avoids the grey film -- it lowers the temperature.  Bravo, Chris.

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Offline Quantumcat

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Re: Why are the yolks of hard-boiled eggs grey around the outside?
« Reply #2 on: 27/08/2003 09:01:45 »
Longer with higher temperature = Greyer. Glad that was finally sorted out. Thanks, Chris.

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Offline chris (OP)

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Re: Why are the yolks of hard-boiled eggs grey around the outside?
« Reply #3 on: 27/08/2003 11:44:33 »
So did you actually try it Quantum ? And it worked ? Nice one !

Chris

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Offline bezoar

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Re: Why are the yolks of hard-boiled eggs grey around the outside?
« Reply #4 on: 27/08/2003 14:53:39 »
I'll bet some chef somewhere has the formula for perfect hard boiled eggs.  Maybe we should have checked the cookbooks.

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Offline cuso4

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Re: Why are the yolks of hard-boiled eggs grey around the outside?
« Reply #5 on: 27/08/2003 21:39:24 »
Try one of Delia Smith's cookbooks.

So...cooling rapidly with cold water cause the reactant to lose energy and therefore unable to perform the reaction.

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Offline bezoar

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Re: Why are the yolks of hard-boiled eggs grey around the outside?
« Reply #6 on: 28/08/2003 07:07:37 »
See?  I knew it.

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Offline Pappy

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Re: Why are the yolks of hard-boiled eggs grey around the outside?
« Reply #7 on: 15/10/2003 21:15:34 »
Bezoar

Indeed, Julia Child has a recipe for "The perfect Hard Boiled Egg" It works every time! Start the eggs in cold water, when the water just starts to boil turn off the heat and let sit for 17 minutes. The immerse in ice water. The perfect egg has no grey line!!
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Offline bezoar

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Re: Why are the yolks of hard-boiled eggs grey around the outside?
« Reply #8 on: 16/10/2003 07:45:56 »
Julia to the rescue.  I learned to cook on one of her cookbooks.  Obviously, not the one with the hard boiled egg recipe.

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Offline Donnah

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Re: Why are the yolks of hard-boiled eggs grey around the outside?
« Reply #9 on: 16/10/2003 16:34:18 »
Bezoar, I bet you're a great cook too.  I'm pathetic in that department, though I make excellent roast beef and yorkshire pudding and, lucky for me, Bruce makes delicious meals.  Maybe we could have a "Science of Cooking" section[:p].
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Offline bezoar

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Re: Why are the yolks of hard-boiled eggs grey around the outside?
« Reply #10 on: 16/10/2003 20:04:00 »
Love to gourmet cook, and spend the day in the kitchen cooking a fabulous meal.  However, in my older years my waistline doesn't like it, so I've gone to healthier cooking.  But you know, living in New Orleans really spoils you for getting used to good food.  Makes it hard to travel cause you can't find a restaurant that even halfway compares to what we have here.
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Offline chris (OP)

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Re: Why are the yolks of hard-boiled eggs grey around the outside?
« Reply #11 on: 17/10/2003 20:38:30 »
I thought they had McDonalds and Burger Kings all over the world, not just in New Orleans [;)]

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Offline bezoar

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Re: Why are the yolks of hard-boiled eggs grey around the outside?
« Reply #12 on: 18/10/2003 09:56:02 »
I do recall going to a Mc Donald's in London.  It was one of the best meals I had there.  You guys definitely do not know what good food is.  The second best meal was right around Windsor castle, and it was Shepherd's pie!  Oh no, y'all need to come visit here for good food.
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Offline Donnah

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Re: Why are the yolks of hard-boiled eggs grey around the outside?
« Reply #13 on: 19/10/2003 03:45:03 »
Bezoar, I second your opinion of the food in London.  Had the most horrible (and expensive) quiche there, among other hideous dishes, and no one knew what ketchup was!
« Last Edit: 19/10/2003 03:45:33 by Donnah »
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Offline chris (OP)

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Re: Why are the yolks of hard-boiled eggs grey around the outside?
« Reply #14 on: 20/10/2003 01:32:36 »
The food must have been bad if you wanted to add ketchup to it !

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Offline Ians Daddy

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Re: Why are the yolks of hard-boiled eggs grey around the outside?
« Reply #15 on: 20/10/2003 04:31:47 »
I dated a girl from England once. I had dinner with her family and it was quite interesting. I learned that alot of the quisine there is boiled. Of course everything here seams to be fried or grilled, so it wasn't too appealing. However, there was this dessert that was awesome. It was alot like flan.
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Offline chris (OP)

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Re: Why are the yolks of hard-boiled eggs grey around the outside?
« Reply #16 on: 20/10/2003 15:57:31 »
That's probably the cheescake then ?

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Offline Ians Daddy

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Re: Why are the yolks of hard-boiled eggs grey around the outside?
« Reply #17 on: 21/10/2003 00:08:58 »
Nah, it was like a stiff vanilla pudding. Mmmmmm, it was good. I think it had cinnamon on it as well. It was alot like flan, but a little fluffier.
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Offline chris (OP)

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Re: Why are the yolks of hard-boiled eggs grey around the outside?
« Reply #18 on: 21/10/2003 00:47:28 »
Yep, sounds like cheesecake. It's called cheesecake but actually isn't made of your average cheddar ! It uses cream cheese on a biscuit base and you flavour it with lemon or, as you say, vanilla and add chocolate sprinkles, cream and fruit to the top. Delicious.

Chris

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Offline tweener

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Re: Why are the yolks of hard-boiled eggs grey around the outside?
« Reply #19 on: 21/10/2003 03:32:13 »
I haven't traveled to England or New Orleans (Closer to there though, being from Arkansas) so I can't comment much on the food in either place.  

But back to the boiled eggs.  How do you change the temperature while boiling the egg?  I always thought that water boils at a fixed temperature, based on the pressure (elevation), and as long as there is liquid water it will never be any hotter.

I know if you leave the eggs boiling for about twenty minutes they end up very hard to break, which is great for easter eggs.  Otherwise I'm no expert since I can't stand a soft boiled egg. And since eggs in general aren't too good for heart health, I just don't eat boiled eggs.

Otherwise, I love food of almost any description, the more spice the better.

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