Measurement of adulteration of olive oils by near‐infrared spectroscopy

Abstract

Authentication of olive oils is of great importance, not only because they command a high price but also because of the health implications of adulteration with seed oils. A method for predicting the level of adulteration in a set of virgin and extra-virgin olive oils adulterated with corn oil, sunflower oil, and raw olive residue oil by near-infrared spectroscopy is presented. The best result was a correct prediction for 98% of the samples. Principal component analysis was used to predict the type of adulterant. The best result was a 75% prediction rate. From these results, it is concluded that it is possible to design a quality control system, which uses near-infrared technology to measure the level of adulteration. In the case where the only test is whether the sample is adulterated or not, a simple calibration for adulteration can be used. The results suggest that principal component analysis may offer a means of identifying the adulterant, although more work is required to give an acceptable level of accuracy.JAOCS 72, 289-292 (1995). KEY WORDS:Near-infrared spectroscopy, olive oil, principal component analysis.

NIR prediction of fruit moisture, free acidity and oil content in intact olives

“…Likewise, the use of NIRS has been evaluated for quality control and the on-line classification of virgin olive oils, analyzing free acidity, bitter taste (K225) and fatty acid composition with interesting results (Jimenez et al, 2005). Moreover, the potential of NIRS to analyze adulteration in olive oil has also been tested (Downey et al, 2002;Wesley et al, 1995;Yang and Irudayaraj, 2001).…”

The Detection and Quantification of Adulteration in Olive Oil by Near-Infrared Spectroscopy and Chemometrics

“…Furthermore, health implications of adulteration of olive oil with seed oils are other concerns. The adulteration of olive oil caused food poisoning in Spain 3,4 in 1981, which resulted in several deaths and caused serious illnesses among people.…”

“…In another application, Bewig et al 18 used a four-wavelength calibration for classifying four different vegetable oils. Wesley et al 3 used the combination for determining corn oil, sun-flower oil, and raw olive residue oil adulteration in extra-virgin olive oil. A similar approach was used to determine sunflower oil, rapeseed oil, and soybean oil adulteration in extra-virgin olive oil.…”

“…The accuracy in the prediction of adulteration in controlled experiments with one olive oil and one adulterant reported in the literature varied from 1.72 to 4.15%. Wesley et al 3,20 showed that they could predict adulteration with an accuracy of 4.15%. Yang and Irudayaraj determined the adulteration of olive pomace oil in extra-virgin olive oil with an accuracy of 1.72%, and Tay et al 16 predicted the adulteration of sunflower oil in olive oil with an accuracy of around 2%.…”

Quality Evaluation of Olives, Olive Pomace and Olive Oil by Infrared Spectroscopy

“…Infrared spectroscopy (NIR and MID), has also been applied successfully for olive oil evaluation and geographical origin determination using chemometric approaches (Tapp et al 2003;Iñón et al 2003;Galtier et al 2007). In addition, NIR technique was employed to detect fraudulent addition of other vegetable oils and olive pomace oil, to virgin olive oil (Wesley et al 1995;Yang & Irudayaraj 2001;Doweny et al 2002;Vlachos et al 2006); and for olive oil authentication (Bertran et al 2000;Downey et al 2003;Woodcock et al 2008). The chemical characterization of fatty acids and sterols (Ollivier et al 2006;Ollivier et al 2003;Aranda et al 2004;Leardi and Paganuzzi 1987), is useful for assessing quality and authenticity.…”