Chemical Analysis of the Egg
Did you ever wonder what the different substances in the egg might be ? One way to find out would be open an egg, remove bits of the contents, and do chemical analyses on them. Of course, that would destroy the egg. Is there a better way ?
One of the tools used by modern chemists for analyzing substances is NMR Spectroscopy. Click here to learn more about it, and for an explanation of the spectra, which are the result of NMR experiments.
Since NMR Spectroscopy uses almost the same equipment as MRI, it is possible to get the chemical analyses of small regions in the egg, using NMR, at the same time as we do MRI to see the structural relationships. This technique is called localized spectroscopy . It isn't necessary to even open the egg for this. We have done this experiment for you, with an unfertilized egg, and the results are shown below.
The first figure shows a side view of the egg, with the boxes indicating the locations from which the spectra came.
The next three figures are the spectra from the three boxes
shown above. Click the images to
display larger versions of the spectra.
||The albumen (white) and latebra are very similar - low in fat, high in water.
||The yolk is almost all fat (lipid) with very little water. Notice the relative amounts of saturated and unsaturated fats.
||But the shape of the water peak is different in the latebra. This accounts for its different appearance on MRI.
Food for thought:
Q1: Why is there a small amount of fat in the latebra spectrum?
Q2: The albumen has a lot of protein in it. Why don't we see that in the spectrum ?
Q3: Is there a difference in fat content or type between the light and dark rings in the yolk?
Q4: What purpose is served by all that fat in the yolk ?
Q5: Why is the yolk at the top in the picture ?
Click here for answers.
C.D.Gregory: April 24, 1996
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