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Why You Should Store Your Eggs Fat End Up

The reason it's smarter to store your eggs with the fat end up is that the egg itself does not completely fill the interior of the shell.

Eggs in open carton

Photo: scottfidd (flickr)

Storing eggs with the fat side up or down might determine the bacteria levels inside the egg

If you think about it, there seems to be no good reason for packaging eggs with their wide end up as opposed to plunking them into the cartons wide-end down: either way will keep the egg from rolling off. Yet cardboard cartons and the plastic egg-tray in refrigerators are made to accommodate a fat-end-up egg. Is there something more here than just coincidence?

In fact, there is: the reason it’s smarter to store your eggs with the fat end up is that the egg itself does not completely fill the interior of the shell. If you crack open a hard-boiled egg carefully at the fat end, you will see that the white part of the egg, called the albumen, does not quite reach the shell — there’s a pocket of air in-between the two. That isn’t the case for the narrow end of the egg, which fits snugly.

That pocket of air allows for the presence, and reproduction, of bacteria. This is not to say there’s something wrong with your egg: any chicken egg will have the air pocket and some measure of bacteria inside it. The trick, then, is to keep the bacteria as far as possible from the yolk, which is much more susceptible to bacterial infection. Albumen contains bacteria-killing enzymes while yolk does not. In other words, the yolk is more perishable than the white.

If you hold the egg fat end down, that air pocket has a tendency to rise — not completely through the egg, but enough to reach the yolk. By storing eggs fat-end up, the pocket of air stays away from the yolk, and the egg stays fresh longer.

  • Gareth Mills

    Thanks, i have my own free range chickens and wasnt sure which was up i was best to store my eggs :D

  • prince99

    storing a fresh egg fat side up ,insures you the egg is fresh abot four months after it’s been layed,,

  • Osako

    Hello. For quite some time I have known that keeping your eggs pointy end up makes them last longer in your shelf. This is from some “did you know” I read some years back. The explanation given was that placing them in that position presses on the air-sac thus limiting conducive air intake by the “chick”. You have to admit this makes some sense, right?

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