Olive oil acidity

The official technique for acidity measure in olive oil is accurate and reliable, but is essentially a laboratory method that must be carried out by trained personnel (mainly because of the toxic compounds used).

The results (i.e. the absorbance data for every tested wavelength) are thus processed by a statistical algorithm, such as Principal Component Analysis (PCA) or Partial Least Squares regression (PLS), to estimate the oil acidity.

The feasibility to measure olive oil free acidity and peroxide value by NIR spectroscopy in the wavenumber range 4,541 to 11,726 cm−1 was reported.

The main advantage of NIR spectroscopy is the possibility to carry out the analysis on raw olive oil samples, without any chemical pretreatment.

The main drawbacks are the high cost of commercial spectrophotometer and the need of calibration for different types of oil (produced by olives of different varieties, different geographical origin, etc.).