Some products presented as extra virgin may, in fact, have been adulterated and not as pure as they seem - but this test will discover the truth
An application note from Biochrom describes how its Libra S22 and S32 spectrophotometers can be used to test olive oil for adulteration according to EC regulations.
The finest olive oil, extra virgin, is produced by the first cold pressing of the fruit.
Other, lower grades can be produced by subsequent extraction processes.
These lower grades can be refined to produce neutral oils that could be blended with the expensive extra virgin oil and are undetectable by odour or taste.
The presence of these lower grade refined oils is, however, detectable by UV/visible spectrophotometry.
Fine spectral detail due to conjugated diene and triene systems characteristic of extra-virgin oil is swamped and lost when refined oils are present, and this is readily observable on the graphic displays of the S22 and S32 instruments.
Regulations 91/2568/EEC and 97/2472/EEC give methods based on multi-wavelength UV measurements that readily detect product adulteration, and use a simple formula to indicate adulteration.
The stored multi-wavelength programs and calculation routines available in the Libra spectrophotometers allow them to be set up as easy-to operate olive oil analysers.
