Using eggshells to skim fat?

I've been reading a memoir by a woman who worked as a cook's helper in the early 1900s. She explains that the cook would put egg shells in the stock and then whisk vigorously. (She doesn't say how finely broken up the shells were.) This would be done for a clear stock to be served as a consomme. It was then this helper's job to carefully skim all the fat from the surface. Does anyone know the purpose served by the eggshells? Apparently they help fat rise to the surface of a liquid? She definitely was not using the eggshells themselves to scoop fat off the surface - they were being whisked into the liquid. Thanks!

  • Posted by: Pegeen
  • March 31, 2012


Jcatky April 9, 2023
My mother used to do this put large pieces of eggshell in the stock - the fats gravitate to the eggshell you can then skim the top
Pegeen March 31, 2012
CO, thanks - re "egg shells alone"
Pegeen March 31, 2012
ChefOno, what is the name of the technique? Thank you.
nutcakes March 31, 2012
It is called forming a raft. Often meat is used as well, maybe more for flavor.
ChefOno April 1, 2012
Yes, the meat adds flavor (to replace some of what is lost during clarification) and also aids in the process. Mirepoix is also a common invitee to the party for flavor augmentation.

ChefOno March 31, 2012
Crud! I meant "may be performed with egg shells alone".

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ChefOno March 31, 2012
The method mbergner describes may be performed with egg whites alone, just not as effectively. It's not about separating the fat but about clarification of the stock, removing the fine particles which make it appear cloudy. As the proteins from the whites and shells coagulate, they bind with the impurities, thus clarifying the liquid. The resulting mass forms a "raft" from which the technique derives its name.
Pegeen March 31, 2012
mbergner - Very interesting. Thank you! The egg whites & shells must be a similar technique to the one SallyBroff referred to. And sieving the stock through a tea towel sounds appropriate to this book. (No wonder they needed servants.)
Pegeen March 31, 2012
Thanks Sally. But she makes a point of saying that the cook "put in the eggshells, not the eggs themselves..." FYI it's a memoir vs. cookbook: "Below Stairs," 1968 by Margaret Powell. Apparently the 1970s BBC series "Upstairs, Downstairs" was based on this book (and then more recently, "Downton Abbey").
mbergner March 31, 2012
I have done the following before; with patience it works well.
Defatting and Clarifying

To get most of the fat out of a stock, you can simply chill it. The fat will harden and float on top of the stock where it can be scooped off easily. One can also use a fat separator, which are like a big measuring cup with a siphon from the bottom, which allows you to pour the stock out while trapping the fat.

To completely clarify stock, use the following method:

Beat egg whites to soft peaks, one for each quart/liter of stock.
Crumple the eggs-shells and mix them through the egg whites.
Stir the mixture in to the stock and bring it to a simmer, do not let it boil. The egg-whites will coagulate, rise, and take any particles and cloudiness out of the stock.
Keep a close eye on the simmer (push the coagulated egg-whites to the side a bit to see) and let it simmer for about ten minutes.
Remove the pot from the heat and let it sit for another ten minutes.
Finally, sieve the stock again through a tea towel.
SallyBroff March 31, 2012
I thought it was an egg white mixedintothe stock.
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