Wednesday, 11 May 2011

How much chlorophyll is in your olive oil?

Different substances absorb different wavelengths of light. Chemicals have their own distinctive absorption fingerprints that can be used to identify when and how much of the material is present. UV-Vis spectroscopy studies the absorption fingerprints of materials in the visible-near ultraviolet range.

Mr Anthony Armstrong Academy Chemistry Teacher explaining UV spectroscopy
Olive Oil is made by pressing and extracting the oil from olives. There are various grades of olive oil. Extra Virgin olive oil is considered the highest quality because it comes from the first pressing of the olives. It has a greenish-yellow tint because of the high levels of chlorophyll. Light olive oil is very light in colour because it has been processed under pressure to remove the chlorophyll and volatile compounds.

Chlorophyll is actually made up of four different pigments. These four pigments absorb light at different frequencies. UV spectroscopy of the chlorophyll in the olive oil creates three blue absorption peaks at 413, 454, and 482 nm, and two red absorption peaks at 631 and 669 nm. The students could compare the amount of chlorophyll in the different types of olive oil.

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