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There's a old wives tale of sugar cooking eggs. I was wondering if there's any substance to that or if it's merely a concentration of the egg as the sugars absorb water.

I was watching The Try Guys and on this pie episode the guest chef explains the various pitfalls of making a pecan pie. She goes on to say how letting eggs and sugar sit together too long will cause the eggs to cook the yolk and possibly ruin the dish. I've never heard of eggs being "cooked" from sugar so I did a brief overview.

Overall, I'm curious if this has any real validity or if it's just a misconception.

The episode is linked along with an article about it. Try Guy Pie Ep @ 7:39 Article

4

The old wives are spectacularly wrong in this case - sugar not only doesn't cook eggs, it makes it harder to cook them.

For example, see this passage from Shirley Corriher's "Cookwise" (emphasis mine):

One day Roland Mesnier, the White House pastry chef, asked me to prepare his lemon curd recipe b heating it on high, bringing it to a boil, and straining it. Knowing that the recipe had no starch and fearing it would turn to scrambled eggs easily, I questioned, "High?" Chef Mesnier stood there with his arms folded across his chest and repeated, "On high".

I obeyed. The split second I saw bubbles, I strained the lemon curd into a cold bowl. Sure enough, I had a tablespoon of scrambled eggs in the strainer, but in the bowl I had a thick lemon curd made in minutes. Chef Mesnier knew that his recipe had enough sugar to prevent the recipe from scrambling instantly and could be cooked over high heat.

When you add sugar to eggs and don't heat, what you get is a sweetened egg mass, and that has nothing to do with a heated/cooked egg mass.

6

It's not really chemistry¹, but simple physics: you can have the same result with salt. (and an experiment you can easily replicate at home: salt is much cheaper than sugar).

What happens is that the salt and the sugar and a whole lot of other things indeed absorb the water in the egg, which makes the proteins in the egg unfold, hook into one another and make these dehydrated eggs look just like cooked eggs where the heat does the same thing: unfold proteins.

Even if you add water again, these polymerized proteins will not re-absorb the water as they cannot unfold just like with a cooked egg: you can easily boil an egg, but it's hard to melt it again afterwards... ;-)

So it's a common misconception as the cooked and the dehydrated versions both look very similar, even under a microscope.

Note¹: To all the chemists and physicists out there: yes, it's an endless debate whether boiling an egg is chemistry or physics... ¯\_(ツ)_/¯

  • Do you have any idea if sugar will cure like salt or kill bacteria like salt or heat? If the sugar does cure it will it be safe to eat? – Jade So Dec 16 '18 at 4:31
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    @JadeSo, you don't say where you are, so the question in your comment is unanswerable. Round here eggs are safe to eat raw, even in pregnancy and for babies. – Chris H Dec 16 '18 at 8:12
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    @JadeSo it is the lack of water that kills or inhibits the growth of bacteria. Both salt and sugar can dehydrate. – moscafj Dec 16 '18 at 13:26
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    @Fabby, as an old Physics guy, we had a saying: If it's green and wiggles, it is Biology. If it smells funny, it is Chemistry. If it doesn't work, it is Physics. Boiled eggs work, not green and wiggle, and smells funny. Gotta be Chemistry. ;) – dlb Dec 18 '18 at 1:53
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    @dlb :D Good one! I would say boiled eggs smell good and don't do anything, so it's Physics. ;-) :P (I'm a Chemist by education, not by trade) – Fabby Dec 18 '18 at 8:18

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