The science museums of San Francisco (California) Exploratorium have a wonderful webpage with plenty of activities to experience science at home. In their cooking section, I found an experiment with which one can explore the phenomenon of osmosis that we were discussing in the last post.

Remember that the reason why osmosis is very important in the kitchen is because the cells that constitute all living beings are subject to it: they consist on a semi-permeable membrane containing a water-based solution in a water-based medium. Where can we find a big single cell to experiment with this? An egg! But eggs come with a shell which does not allow water to go through. To play around osmosis we must first of al strip the eggs naked.

I followed the instructions on Exploratorium and put 10 eggs in a plastic container covered in white vinegar. After 24h, the shell had began to dissolve because of the action of the vinegar on the solid calcium carbonate crystals that make up the eggshell and one can easily rub the shell off the egg as shown:

Eggs after 24h in vinegar.

Eggs after 24h in vinegar.

What the vinegar does is brake them into their calcium and carbonate parts (the carbonate combines with the oxygen in the water to make carbon dioxide, which are the bubbles that you see forming around the egg shells). This process neutralizes the solution so after 24 hours it is necessary to replace the vinegar with new one.

One day and a half after that, most of the shell of the eggs was completely gone! I rinsed them with water one by one and change half of the vinegar by new one to finish the result. These are the eggs at that stage:

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Eggs after 2 days and a half in vinegar.

Eggs after 2 days and a half in vinegar.

After three days and a half swimming in vinegar, the eggs had completely lost their shells and I had 10 big isolated cells to experiment osmosis with:

Eggs after 3 days and a half in vinegar.

Naked egg after one night in syrup.

To do this, submerge one of the eggs in some kind of syrup (corn syrup, black syrup) which is very concentrated and has a low content in water (about 25%). The next morning your egg will look like this:

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Naked egg after one night in syrup.

Naked egg after one night in syrup.

And in the pot you will see how the syrup is now liquid because part of the water inside the egg has migrated through the membrane to the outside, leaving you with a  fluffy egg and some liquid syrup.

However, if you put your egg in water again, after a few hours it will look like this:

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All plumpy and full of water again. Here you can see it next to an egg who spent the night swimming in syrup so that you get an idea of the change in size due to osmosis:

The effects of osmosis in eggs.

The effects of osmosis in eggs.

There are other things you can do with these naked eggs. For example, you could boil them in a cubic container and make cubic boiled eggs. Last night I could not find such a container, so I just put the egg in a box and made a (not very succesful) flat boiled egg instead:

Flat boiled egg next to a raw naked egg.

Flat boiled egg next to a raw naked egg.

In the process of looking for an appropriate recipient to boil the egg in, I broke one of them and found my self with the membrane in my fingers. This is what it looks like:

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Also, you can put the eggs in water with food colorant. This is the result:

Naked eggs died with food colorant.

Naked eggs died with food colorant.

Do you have any other ideas of what one could do with these naked eggs? Share them with us in the comments section!

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