I know that if there is even a bit of yolk in egg whites that they won’t beat well, and that it is impossible to get stiff peaks. Over the years, I’ve often broken a yolk when separating the whites from the yolks and ended up discarding the egg white (or the whites from multiple eggs if I was being cavalier and had assumed that I wouldn’t have problems and directly separated eggs into a bowl that already had whites from other eggs). But I never knew why until I read a short article in a hundred-year-old magazine. (It’s amazing how many new things I’ve learned over the years from old books and magazines.)
Why Does Yolk of Egg Keep White from Beating Stiff?
If even a small portion of the yolk of the egg gets mixed with the white, this will keep the white from beating to the same kind of stiff froth that the white alone will beat into, because there is enough oil present, in the little portions of yolk, to keep down the froth. You know you cannot beat olive oil, for instances, into a froth. You know that “pouring oil on troubled waters” is a very real, rather than poetical expression of the smoothing-down effect of oil on a rough sea and angry breakers. Yet if only a very little of the yolk gets mixed with the white, and if you beat long and hard, you will get a fluffed up mass, though not of the same texture attainable by beating of the white alone.
American Cookery (December, 1924)
Okay, I guess this makes sense – but I’m still a little confused. Why can heavy cream (with lots of fat) be whipped into stiff peaks, while skim milk (with no fat) doesn’t whip at all?
I’m very glad to know the why. I knew yolk was a disaster for whites, but I didn’t know the fact behind it. Thank you.
It’s nice to hear that you enjoyed this post. I’m constantly surprised by how many “new” things I learn from old cookbooks.
Thank you for sharing the things you learn from the old cookbooks.
Interesting question! It seems the fat in the egg yolk interferes with the formation of the foam. We found this link useful: https://www.exploratorium.edu/explore/cooking/pavlova
Thanks for sharing the link. There is a lot of really useful information in the article – how the temperature of the egg whites affects how well they beat; that whites don’t beat as well when a plastic bowl is used; and how to salvage overbeaten egg whites.
I knew egg yolk in whites meant no stiff peaks and was perplexed as to why skimmed milk contradicted the fat theory…I came across which seems to debunk the premise that you can’t whip skimmed milk. https://youtu.be/aQAq8i7__M4?si=gKtJ5yzxIYQa8-zR
Interesting about whipping skimmed milk. I don’t have the equipment they used, but it would be fun to try. In the video, it doesn’t look like stiff peaks were formed, but rather very soft peaks. I once tried beating half and half with a regular electric beater, and that was a disaster.
Yes I have one of those on my food processor so I may give it a go when I have a spare moment and some skimmed milk 🙂
If you give it a try, you’ll have to tell us how it turns out.
This is really interesting. I didn’t know about the bit of yolk causing the whites not to peak. I wished I had of, because it would explain some of the troubles with my meringues. I gave up years ago on trying to get them to peak and stopped trying to make them at all. I may have to try and make a pie soon and be extra careful when making a meringue for it. Your blog is very helpful. Thanks so much. 😊
Thanks for the kind words It’s nice to hear that the things I post are helpful. Egg whites can be very finicky when it comes to beating them, and just a little yolk can cause problems.
Interesting! As to the cream – you have to incorporate it AFTER you’ve beaten the whites, don’t you? It wouldn’t work in the beginning, I guess?
Yes, don’t add cream (or sugar) to the egg whites until after they are beaten. I think that some of the comment writers have shifted to talking about whipping cream rather than whipping egg whites.
Hmmm..some answers lead to more questions.
Agree- answers leading to more questions keeps things interesting. 🙂
Hmm. I was making a dessert that called for meringue and accidently add 1/4 t. oil and it worked great. The meringue had beautiful peaks and the oil made it just slide out of the bowl! I must have just gotten lucky….
Interesting – I’m glad it turned out well. I sure don’t understand all the science that underlies beating eggs and making meringues.
Basic layman’s understanding: in dairy products it is the fat itself which coagulates when whipped, hence if you whip cream too long it turns into butter. Meringue comes from air being mixed into the egg whites, and coagulation of fat is not involved.
Thanks for explaining. It’s fascinating how, on the surface, the processes for making whipped cream and meringue seem very similar, while the underlying scientific principles are very different