Why use copper to beat eggs?

[Shaheen]

I was watching Friends and in it Rachael was beating something in a copper vessel. I remember having read somewhere that beating eggs(it's egg right? or something else?) in a copper bowl gives good results. Why is it so? I need help remembering that. Thanks

 

[Andy M.]

Beating egg whites into a meringue in a copper bowl will give you fluffier whites faster. There is a chemical reaction with the copper surface of the bowl that speeds the process.

 

[licia]

I remember Natalie ............, can't remember her last name who used to beat the egg whites in a copper bowl and hold them over her head with the bowl upside down to show how stiff and together they were.

 

[kadesma]

I remember Natalie ............, can't remember her last name who used to beat the egg whites in a copper bowl and hold them over her head with the bowl upside down to show how stiff and together they were.

I remember her too licia, I think her last name was Dupree..Use to watch all the time. Fun show.

kadesma

 

[corazon]

Rachel doesn't know how to cook anyway.

 

[Michael in FtW]

It probably was Nathalie Dupree ... Shirley Corriher discusses testing out the "copper bowl" mystery with some of the staff at Nathalie's cooking school in her book Cookwise (pages 234-235).

In short - the protein in egg whites that links together around the air bubbles created from whipping the whites forms a chemical bond with the copper ions in the bowl. While it doesn't increase the volume per se - it does stabalize them, they loose much less moisture, and increases the volume of the final product significantly since they do not deflate and lose moisture like whites whipped in other bowls (glass, stainless steel, etc.)

 

[Shaheen]

Rachel doesn't know how to cook anyway.

I know! It was the episode in which she makes a mixture of English Trifle and Shephard's Pie

 

[corazon]

Ah yes, I know that episode. That is one of my favorite ones! Sorry to highjack the thread.

 

[Andy M.]

Getting back on topic, the subject is beating eggs in copper bowls...

 

[licia]

Natalie Dupree used to clean her copper bowls with vinegar and salt just before she beat the egg whites. I think she said it was to make sure no speck of oil was in the bowl. I don't know if that method was hers or from someone else and she used it. I just beat mine in an "impeccably clean"(ala Julia Child) glass bowl. Not that Julia used glass, but she always stressed the impeccably clean part, whether it was fingers, spoons, bowls, etc.I always liked the way July used a clean teaspoon to taste whatever she was cooking. I hate to see someone taste from the stirring spoon and continue using it. Justin Wilson was the worst for doing that, but I wouldn't have eaten what he cooked anyway. He always seemed a bit unsanitary to me.

 

[Andy M.]

Any kind of fat residue on the equipment used to whip egg whites will impair or prevent the creation of the meringue.

Any material except plastic can be used. Plastic molecules are so similar to fat molecules that they can inrterfere with meringue creation as well.

 

[subfuscpersona]

if you can't afford an unlined copper bowl just for stiffly beaten egg whites (and how many of us can?) try adding a pinch or two of cream of tartar to your egg whites at the point when they start to froth, then continue whipping until they are the stiffness desired (the stiffness is defined by how well the egg whites hold a peak)

 

[Michael in FtW]

Yes, subfuscpersona - cream of tarter, or even some vinegar, will help to stabalize beaten eggg whites. However, neither will do what a copper bowl will. Since I hate to recreate the wheel ... try reading what Shirley Corriher has to say about the experiments she conducted at Natalie Dupree's cooking school, and her discussion with Dr. Ing. C. Peng at Perdue University, in her book Cookwise, pages 234-235.

Shaheen's original question wasn't asking about how to stabalize egg whites - the question was "why use copper".

 

[Chopstix]

Am paraphrasing this explanation from another site:

Copper bowls produce a yellowish, creamy foam that is harder to overbeat than the foam produced using glass or stainless steel bowls.

When whisking egg whites in a copper bowl, copper ions from the bowl combine with some of the egg white proteins making them more stable. The act of whisking egg whites makes the un-ionized proteins coagulate, stiffening the foam and sealing in the air bubbles.

If the foam is overbeaten in a non-copper bowl, eventually all the egg white proteins coagulate into clumps.

If a copper bowl is used, only the un-ionized proteins are free to coagulate, making the eggwhites harder to overbeat.