eksperimenti iz kuhinje Roberta Krampfa...

prvi, pandan ultrazvuku u trudnoci (sve dok se ne razbije jaje)


This Week's Experiment - #463 Eggs-ray Vision

This week's experiment came from trying to hatch some eggs. We are using an incubator, and hoping to hatch some chicks and ducks. This week, we candled the eggs, to see if they were developing. Candling is a technique for looking inside an egg, without breaking the shell. To try this, you will need:

an egg
a bright llight
a cardboard box
a dark room
a small bowl or dish

First, cut a hole about the size of a quarter in the bottom of the cardboard box. Turn the box upside down, and put the bright light inside. Position the light so that it is shining up through the hole. Then darken the room and place the egg over the hold. The light should shine into the egg, making it glow.

Look carefully at the egg. If you were looking at a fertile egg that had been incubated for a couple of weeks, you would see a large, dark mass. That would be the baby chick.

While you won't see that in your egg, you can see a few things. First, you can see the air cell. It will look like a small bubble at the large end of the egg, and that is exactly what it is. In a fresh egg, it is small, but if you keep the egg in the refrigerator for a while, it loses part of its water and the air cell gets bigger.

You may also see lots of tiny light spots in the shell. Those are pores that let the egg breath. It lets oxygen get in, and lets carbon dioxide and water get out.

If you have a very bright light, you may see just a hint of the yolk. That is about all that you should see by candling, but by breaking the egg, we can learn even more about the inside. Carefully crack the egg into a small bowl or dish. Try not to break the yolk.

Look carefully at the inside of the shell. Along the inside of the hard shell, you should see a thin, skin-like membrane. Actually, there are two membranes, one inside the other. If you look at the inside of the large end of the egg, you should see the air cell, in between the two membranes. These membranes control what goes in and out of the egg, keeping it from drying out, and helping to keep out microorganisms that would spoil the egg.

Next, look at the egg. Most people are familiar with the white or albumen (which comes from albus, which is latin for .... you guessed it. White.) Inside the albumin is the yolk. Many people think that the yolk develops into the chick, but it does not. Instead, the yolk is a stored food supply to feed the chick until it hatches. Even if you have a fertilized egg, the part that will develop into the chick is VERY tiny, so don't expect to see it.

In the albumin, you may also see one or two small, white structures. Again, many people think that this is the start of the chick. Instead, these are chalazae, rope-like structures that hold the yolk in the center of the albumin. By keeping it away from the shell, they protect the yolk from contamination by any microorganizms that find their way into the egg. That is also why you should store eggs with the large end up. Since the air cell is an air bubble, it tries to float upwards. If the large end of the egg is down, the air cell stretches upwards, bringing it closer to the yolk, which could cause the egg go bad quicker.

Now that you have dissected the egg, the only thing left to do is to denature its proteins. To do that, put a little butter into a skillet. Turn the heat on medium and place the egg into the skillet. The heat will change the protein of the egg, causing the albumin to change from a clear gel to a firm, white solid. The yolk will also take on a firm texture. Then add a little salt and pepper and you have a very nice snack.

Have a wonder filled week.