Chemistry of egg and cornstarch sauce in this recipe



beyondcelery December 21, 2012
Thanks, everyone! I understand this technique much better now. I can't wait to try it on all sorts of things.

@Ascender: I think you're right that the egg created a broken emulsion. It actually looked sort of like a broken mayonnaise. Thank you! Next time I'll try tempering it.
inpatskitchen December 21, 2012
I love the "velveting" technique with really does protect the protein. I basically just use egg white for it though, as in this recipe:
Ascender December 21, 2012
The "velveting" technique can be done with any thinly sliced meat before stir frying it. I love how tender and moist it makes pork.

Adding the egg to the sauce at the end may have created a broken emulsion, like when mayonnaise breaks. It may have worked better if you'd tempered the egg into the sauce.
boulangere December 21, 2012
Yes, that's exactly what happened - an instantly broken emulsion. If some of the sauce had been tempered into the beaten egg, then that combination whisked into the sauce, preferably off the heat, the result would have been lovely and silken. It sounds as though it was delicious nonetheless!
beyondcelery December 21, 2012
Cool, I did notice the chicken stayed more moist than usual. Thanks!

But with the sauce, I added the rest of the whole beaten egg, not just the white. It didn't bind to the fat, but only made the sauce separate. It had pools of oil/fat and the rest sort of looked curdled (probably the cooked egg). It didn't behave the way egg white does in a consomme. But perhaps it's the same principle?
Sam1148 December 21, 2012
The egg and cornstarch mix helps create a shell around the chicken so it's moist when cook. Look up Veleting. Or Velvet chicken.

I with the egg whites added to the oily stock, I think you recreated 'egg white clarification' the white attract the fat bit from the stock. Great technique if your making a consomme.
beyondcelery December 21, 2012
It posted too soon! More details: I made this last night and it tasted fantastic. How does the 1 tsp beaten egg in the marinade affect the chicken with the cornstarch? Is it completely essential? Also, I hate not using up an ingredient, so I poured the rest of my beaten egg into the sauce at the finish (egg flower soup-style) and it caused the oil in the sauce to completely separate from the rest. The end result was rather ugly, but still tasty. Why did the egg cause that? What's the chemistry behind it?
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