Analysis of olive oil with FT-NIR spectroscopy
QC of Olive Oils
An acidity value below 0.8% is the main criterion for the classification of the olive oil as “extra virgin”. Other quality parameters include the peroxide value, an indication for the rancidity of the oil as well as as well as the K-values (UV absorption) and many others.
Unlike wine, the quality of olive oil does not improve with age and sooner or later it will become rancid. The amount of 1,2-diglycerides as well as the pyropheophytin content in the oil reveals if a an olive oil was stored for too long or even adulterated with refined (olive) oils to obtain lower acidity values.
All these critical parameters can be tested with a 30 second FT-NIR measurement, enabling a thorough quality control along the production chain of the oil.
Testing on adulteration
A common problem not only for the olive oil industry is the adulteration of high priced olive oil with cheaper seed oils such as sunflower or hazelnut oil. Today’s public awareness of the health benefit of olive oil makes the adulteration economically attractive. Chemically, most oils are very similar and a blend is difficult to identify with common quick tests like measuring refractive index.
However the different oils vary in their fatty acid profile and FT-NIR spectroscopy can offer a valuable tool for determining other types of oil in olive oil down to a low percentage range. Another issue regarding adulteration is to determine the geographic origin of the oils for certification purposes (RDO labeling). Combined with other techniques, FT-NIR can deliver valuable supplementary information.
A good product requires a complete control along the production chain.