Olive oil assessment in edible oil blends by means of ATR-FTIR and chemometrics

Abstract

Oil blends containing olive oil are commonly commercialized due to economical and nutritional reasons. According to European trade standards only when an oil blend contains more than 50% (w/w) of olive oil it can be marketed with images or graphics highlighting its presence. In this work a fast method for verifying the correct labelling of such oil blends was developed. First, the capability of attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy to distinguish olive oil was tested both in pure oil samples and in blends of different oils by using a method based on partial least squares discriminant analysis (PLS-DA). 100% of the olive oils samples were correctly identified within a wide collection of pure samples of different types of vegetable oils including olive oil of different categories, varieties and origin. When studying oil blends, it was possible to differentiate between blends with olive oil content higher than 50% (w/w) and below 50% (w/w). Finally, an attempt of quantification of olive oil in blends based on PLS regression was performed. For blend samples with olive oil contents up to 50% (w/w) a prediction error of 8.28 was obtained.